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Equipment, Gear Reviews, Informational

SharpStar SCA310 Review (Part 2)

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Refining the Setup and Seeing What It Can Really Do

In Part 1 of my SharpStar SCA310 review, I covered the rather long journey that eventually resulted in one arriving on my doorstep, the technical specifications, how it compares with my previous SharpStar 20032PNT and my initial impressions of what is, by any measure, a substantial piece of astrophotography equipment.

But specifications and first impressions only tell you so much.

The real test of any astrograph begins when you start building the complete imaging system around it and, ultimately, point it at the night sky.

Since receiving the SCA310 in January, I’ve made a number of changes to get the telescope working exactly the way I want it. Some were planned before it even arrived, while others came about as I started collecting real imaging data.

So, in Part 2, I’ll concentrate on those experiences: what I changed, the problems I encountered, how I solved them and, ultimately, whether the SCA310 delivered the performance I’d been waiting more than four years to see.

Re-engineering the Cooling System

One of the first things I decided to change was the cooling arrangement.

The SCA310 is fitted with fans behind its large 310 mm primary mirror, but I wanted to make two modifications.

The first was purely practical. I replaced the original fans with externally mounted, easily replaceable units. Fans are mechanical components and eventually they fail. I didn’t want replacing one to involve dismantling the rear of the telescope, so with my arrangement a failed fan can now simply be swapped out.

The more significant change was reversing the direction of airflow.

In the stock configuration, air is drawn through the open aperture and exhausted by the fans behind the primary mirror. I reversed this so that the rear-mounted fans instead draw ambient air in from behind the primary and push it forwards through the telescope.

The main reason for doing this was the thermal boundary layer that can form above a large primary mirror. If the mirror remains warmer than the surrounding air, it heats the thin layer of air immediately above its surface, creating small convection currents that can affect image quality.

By bringing ambient air in behind the primary and moving it forwards, the aim is both to help the mirror reach thermal equilibrium and to disrupt that warmer boundary layer.

There’s also another potential benefit. The airflow continues forwards towards the secondary, helping keep air moving around it during the damp conditions we frequently experience here in the UK. It isn’t a replacement for dew control, but anything that helps discourage moisture from settling on the secondary is useful.

This isn’t something I’ve attempted to quantify scientifically; it’s simply the approach that made most sense to me, and in practice it has worked extremely well.

My externally mounted cooling fans. As well as reversing the airflow, mounting the fans externally means they can easily be replaced should one ever fail.

Tracking Down the Stray Light

Once I started collecting real-world imaging data, I discovered another issue: stray light.

I contacted SharpStar and shared examples of what I was seeing. To their credit, they responded by providing me with a corrector baffle extension, designed to provide additional shielding and control stray light hitting the corrector lens. Once installed, it made a significant improvement.

Unfortunately, the stray light didn’t stop there.

When I subsequently examined my RGB imaging data, I noticed another reflection that was particularly apparent through the Red and Green filters, with Red showing the strongest effect.

This appeared to be separate from the stray light that SharpStar’s corrector baffle extension had addressed, so I started looking for another reflective surface within the optical path. Eventually, I traced it to something surprisingly simple: the red anodised aperture.

Although it didn’t look particularly reflective to the eye, it was reflecting enough light to become visible during long-exposure imaging, particularly through the Red filter. Fortunately, the solution was equally simple. I covered the inside of the red anodised aperture with black insulation tape. And that solved it.

Not exactly high-tech, but extremely effective. Black insulation tape covering the reflective anodised surface eliminated the remaining reflection.

It’s worth distinguishing between the two issues.

The corrector baffle extension supplied by SharpStar controlled stray light reaching the corrector lens, while the remaining RGB reflection was caused by light reflecting from the red anodised aperture.

Given that mine was an extremely early SCA310—and, as far as I’m aware, the first delivered to a customer in the UK—finding a couple of areas that could be refined wasn’t entirely unexpected.

More importantly, neither issue was related to the fundamental optical quality of the telescope.

Collimation – Easier Than Expected

Given the size of the SCA310 and its fast f/3.8 optical system, I expected collimation to be one of the more challenging aspects of setting it up.

In reality, it was surprisingly straightforward. I used my Farpoint Astro laser collimator for the initial alignment, making a few small adjustments until I was happy everything was correctly aligned. Of course, the final test isn’t where the laser lands. It’s the stars.

Once I was able to examine actual imaging data, I checked the entire star field rather than concentrating solely on the centre. The result confirmed what the Farpoint had indicated: tight, round stars across the whole field of view, including the corners.

“The laser gets you aligned, but ultimately the stars tell you whether you’ve got it right.”

I’ve also found the SCA310 to hold its collimation extremely well. Mine is permanently installed in the observatory, which undoubtedly helps, but I haven’t found myself constantly having to make adjustments.

My approach now is simple: check it, but don’t touch it unless the stars tell me there’s a reason to.

Replacing the Stock Focuser with the Esatto 3.5″ LP

The next change was one I’d largely planned from the beginning. There was nothing fundamentally wrong with the stock focuser, but I wanted something better suited to a permanently installed and highly automated imaging system. I therefore replaced it with a PrimaluceLab Esatto 3.5″ LP robotic focuser.

For me, the main advantages are rigidity, repeatability and accurate automated focusing throughout the night. With an OAG, filter wheel and full-frame camera hanging from the rear of the telescope, maintaining a rigid imaging train is particularly important.

The original SCA310 connection is M101x1, so fitting the Esatto required an M101x1 female to M101x1.5 male adapter. Once installed, everything fitted together extremely well.

The original SCA310 focuser before the upgrade.

The PrimaluceLab Esatto 3.5″ LP installed using an M101x1(F) to M101x1.5(M) adapter.

For the way I use the telescope, the Esatto has proven to be a worthwhile upgrade. Autofocus is repeatable, the imaging train is extremely rigid and it integrates neatly with the rest of my observatory automation.

Moving from a Guide Scope to an OAG

Changing the focuser wasn’t the only alteration I made to the imaging train. With a telescope of this size and a focal length approaching 1.2 metres, I also decided to retire my separate guide scope and move to an Off-Axis Guider (OAG).

The advantage is straightforward: an OAG guides using the telescope’s own optical path, eliminating the possibility of differential movement between a separate guide scope and the main telescope. In principle, it was an obvious upgrade. Getting everything configured proved slightly more challenging.

The main issue was achieving reliable guide-camera focus while also dealing with the small differences in focal point between my individual filters. As the imaging camera refocused between filters, I needed the guide camera to remain sufficiently well focused across those changes.

It took some experimentation with positioning and spacing, but eventually I found the right compromise. Once sorted, the OAG has worked extremely well, and on a telescope of this size I wouldn’t go back to a separate guide scope.

First Completed Image – The Wizard Nebula

After modifying the cooling, dealing with the stray light, checking the collimation and finally getting the imaging train configured exactly the way I wanted it, there was really only one thing left to do.

Take some photographs.

My first completed image with the SCA310 was the Wizard Nebula (NGC 7380), and this was probably the point at which the four-year wait finally made sense. The first thing I did was examine the stars.

Not just those in the centre of the image, but those right out towards the corners. The result was exactly what I’d been hoping for. Tight, round stars across the entire field of view.

The overall image was also extremely sharp, with fine structure throughout the nebula beautifully resolved. This was my first real opportunity to see what the combination of 310 mm aperture, 1178 mm focal length and f/3.8 could deliver in a completed image rather than simply looking at test exposures. And it delivered.

My first completed image with the SharpStar SCA310 – the Wizard Nebula (NGC 7380). The image demonstrated excellent sharpness with tight, round stars across the entire field of view.

“After more than four years of waiting, the Wizard Nebula was the image that finally answered the question: was the SCA310 going to deliver what I’d hoped? It absolutely did.”

And ultimately, that’s what matters. Cooling systems, focusers, collimation, guiding and modifications are all part of building an astrophotography system, but the reason we spend so much time getting those things right is the image that eventually appears on the screen.

Which brings me to the question I’ve been waiting more than four years to answer.

Conclusion – Was the SharpStar SCA310 Worth the Wait?

After waiting more than four years for the SCA310, there was always a danger that no telescope could possibly live up to the expectations I’d built around it. Fortunately, this one has.

It hasn’t been a completely plug-and-play experience. I’ve modified the cooling system, dealt with two different sources of stray light, changed the focuser and moved from a guide scope to an OAG. But none of those things change what matters most. The optical performance is exceptional.

The Wizard Nebula demonstrated that better than any specification sheet could: excellent sharpness and tight, round stars across the entire field.

I also don’t want the move to the SCA310 to suggest there was anything lacking in my previous SharpStar 20032PNT. There wasn’t. It was an excellent telescope and produced many images I’m still extremely proud of. The SCA310 simply represents the next step.

Its additional aperture and longer focal length give me access to a different level of image scale and detail, while the f/3.8 optical system retains the imaging speed that attracted me to SharpStar’s astrographs in the first place.

There are certainly areas where I think SharpStar could make improvements. Better stray-light control from the factory would have prevented the issues I encountered, and personally I prefer the cooling arrangement I’ve created.

But those are refinements around an optical system that has delivered exactly what I hoped it would.

There is one other consideration for anyone thinking about buying one.

It’s huge.

At 23.5 kg before adding the complete imaging train, the SCA310 needs a serious mount underneath it. Mine sits permanently on my Sky-Watcher EQ8 Pro, which is now around twelve years old and was StellarDrive tuned a few years ago. Despite its age, the EQ8 continues to handle the SCA310 extremely well.

I wouldn’t underestimate this aspect of ownership. There’s little point investing in optics capable of resolving extremely fine detail if the mount underneath them can’t provide the tracking and guiding accuracy needed to take advantage of it. So, would I buy the SCA310 again?

Absolutely.

I’ve only had it since January, and in many ways I’m still discovering what it’s capable of. I’m sure there will be many more targets to image—and, knowing me, probably a few more refinements to the setup along the way.

But after following its development for more than four years, finally having Zoltan from 365Astronomy drop it off on his way home from AstroFest, and then spending the months since learning how to get the best from it, I can finally answer the question I had when SharpStar first announced the SCA310.

Was it worth the wait?

Without hesitation. Every single year of it.

Equipment, Gear Reviews, Informational

SharpStar SCA310 Review (Part 1)

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Four Years of Waiting… and Every Lesson Learned Along the Way

Introduction

Every now and then, a telescope comes along that genuinely captures the imagination of the astrophotography community.

For me, the SharpStar SCA310 was one of those telescopes.

Having previously owned both the SharpStar 15028HNT and later the SharpStar 20032PNT, I’d become a huge fan of SharpStar’s approach to designing telescopes specifically for astrophotography. The 20032PNT, in particular, had become my workhorse telescope, producing many of my favourite deep-sky images and proving itself to be an exceptionally capable imaging platform.

So, when SharpStar announced the SCA310 Super Cassegrain Astrograph, my interest was immediate.

On paper, it promised something genuinely different. A completely new optical design, a 310 mm aperture, 1178 mm focal length, f/3.8 optical system, and a 55 mm corrected image circle housed within a beautifully engineered carbon fibre optical tube. It wasn’t simply a larger version of the 20032PNT—it was an entirely new design of telescope aimed squarely at serious astrophotographers.

Like many people, I expected it to be available within a few months.

Unfortunately, that wasn’t to be.

Manufacturing delays, global supply chain issues and extremely limited production meant that what I thought would be a relatively short wait eventually stretched into more than four years. As each year passed, the SCA310 became one of those telescopes that many of us wondered if we’d ever actually get the opportunity to own.

Then, in February this year, the wait was finally over.

Following AstroFest UK, Zoltan from 365Astronomy kindly dropped the telescope off to me on his journey home from the show. After following the SCA310’s development for more than four years, finally seeing it arrive on my doorstep was a genuinely memorable moment. As far as I’m aware, I also became the first person in the UK to take delivery of a SharpStar SCA310.

Needless to say, my expectations were incredibly high.

After waiting that long, I couldn’t help wondering whether any telescope could possibly live up to the anticipation.

Thankfully, it did.

That doesn’t mean the journey was entirely straightforward.

Like any sophisticated imaging system, the SCA310 required time to understand. Over the months that followed, I refined the cooling system, investigated and resolved an internal reflection issue, upgraded the focuser, redesigned the imaging train and learned exactly how to get the very best from the telescope.

This article isn’t another “first light” review written after a single clear evening.

Instead, it’s a long-term owner’s perspective. I’ll cover not only the official specifications and optical design, but also the practical realities of living with the telescope, the modifications I chose to make, the challenges I encountered and—most importantly—whether it was ultimately worth waiting more than four years to own one.

If you’re considering an SCA310, I hope this review gives you the insight that only comes from spending months living with the telescope rather than simply reading a specification sheet or watching a first-light video.


From the SharpStar 20032PNT to the SCA310

Before the SCA310 arrived, my primary imaging telescope was the SharpStar 20032PNT. If you’ve read my review of that telescope, you’ll already know how highly I rated it. It produced many of my favourite astrophotography images and, over the years, proved itself to be an exceptionally reliable and capable imaging platform.

In fact, when the SCA310 was first announced, I wasn’t actively looking to replace the 20032PNT. It already did everything I asked of it. The optics were excellent, the mechanical construction was solid, and paired with my imaging setup it consistently delivered sharp, well-corrected stars across a full-frame sensor.

So why change?

Quite simply, the SCA310 offered something entirely different.

Rather than being an evolution of the 20032PNT, the SCA310 represents a completely new optical design. SharpStar’s Super Cassegrain Astrograph (SCA) architecture combines a significantly larger aperture with a fast f/3.8 focal ratio and a generous 55 mm corrected image circle, opening up possibilities that simply weren’t available with my previous setup.

The most obvious difference, of course, is the aperture.

Moving from 200 mm to 310 mm is a significant step. The increase in light-gathering capability means faint structures can be recorded more efficiently, while the longer focal length provides greater image scale for smaller galaxies, planetary nebulae and distant deep-sky objects. It isn’t simply a case of “bigger is better”; it’s about having a telescope capable of revealing more subtle detail when the seeing conditions allow.

There are, however, trade-offs.

The SCA310 is in a completely different class when it comes to physical size. Photographs really don’t prepare you for just how substantial it is. Even before cameras and accessories are attached, it dominates the observatory. Once the complete imaging train is installed, including the electronic focuser, off-axis guider, filter wheel, camera, dew control equipment and cabling, the finished system represents a considerable payload.

Fortunately, my observatory was already equipped to handle it.

The telescope now sits permanently on my Sky-Watcher EQ8 Pro, a mount I’ve owned for around twelve years. A few years ago it was professionally upgraded with a StellarDrive tuning kit, transforming what was already a capable mount into one that has handled every telescope I’ve asked it to carry. The SCA310 is undoubtedly the largest and heaviest optical tube I’ve mounted on it, but the combination has proven to be an excellent match.

For anyone considering an SCA310, it’s worth remembering that purchasing the telescope is only part of the investment. A telescope of this size deserves a mount capable of supporting it with absolute confidence. Skimping on the mount is likely to compromise the very performance you’re buying the telescope to achieve.

SCA310 vs 20032PNT

While both telescopes were designed specifically for astrophotography, they target slightly different requirements and imaging styles.

FeatureSharpStar 20032PNTSharpStar SCA310
Optical Design200 mm Paraboloid Astrograph310 mm Super Cassegrain Astrograph
Aperture200 mm310 mm
Native Focal Length760 mm1178 mm
Imaging Focal Ratiof/3.2 (with integrated corrector)f/3.8
Corrected Image Circle44 mm55 mm
Tube MaterialCarbon FibreCarbon Fibre
OTA Weight9.46 kg23.5 kg (including rings, handle, dovetail and corrector)
Rear ConnectionsM68 / M54 / M48M68 / M54 / M48
Rear-end Connection DistanceFixed imaging configuration38–66 mm

Looking purely at the specifications, it’s easy to focus on the larger aperture and increased focal length, but for me that wasn’t the biggest attraction.

What really interested me was the opportunity to work with an entirely new optical design. Having enjoyed such excellent results with the 20032PNT, I was keen to see what SharpStar could achieve by starting with a clean sheet of paper and designing a telescope specifically around the needs of modern astrophotography.

As I was about to discover, that new design brought with it some impressive advantages… and a few interesting engineering challenges along the way.

Technical Overview

The SharpStar SCA310 isn’t a larger version of SharpStar’s existing astrographs. It represents a completely different approach to telescope design, developed specifically for deep-sky astrophotography rather than adapting an existing visual telescope.

At the heart of the SCA310 is SharpStar’s Super Cassegrain Astrograph (SCA) optical system which is actually a modified version of the Dall-Kirkham. The telescope combines a 310 mm aspherical primary mirror, a 184 mm fused silica secondary mirror, and an integrated three-element corrector incorporating an ED element. Working together, these components produce a 55 mm corrected image circle, making the telescope suitable for everything from full-frame astronomy cameras through to many medium-format sensors.

For me, one of the most attractive aspects of the design is that SharpStar hasn’t simply chased the fastest possible focal ratio. Instead, they’ve balanced aperture, focal length and image quality to produce a telescope that offers excellent image scale while remaining fast enough to collect an impressive amount of signal during a night’s imaging.

At 1178 mm focal length and f/3.8, the SCA310 sits in a very interesting position. It’s long enough to frame galaxies, globular clusters and many smaller nebulae with excellent detail, yet still fast enough to make broadband and narrowband imaging practical without excessively long exposure times.

That combination was one of the main reasons I decided to wait for the telescope rather than purchasing something else in the meantime.

Designed for Modern Imaging Systems

One feature that particularly stood out to me when reading the specifications was SharpStar’s approach to the rear of the telescope.

Many astrographs specify a fixed back focus that has to be maintained with millimetre precision.

The SCA310 is different.

Instead of defining a fixed back focus, SharpStar specifies a rear-end connection distance of between 38 mm and 66 mm. That may sound like a small detail, but in practice it provides significantly more flexibility when designing an imaging train.

Whether you’re using a motorised focuser, an off-axis guider, a filter wheel, a camera rotator or a combination of accessories, the available connection distance makes it much easier to configure the system without feeling constrained by a single fixed spacing.

As you’ll see later in this review, that flexibility proved particularly useful when I upgraded the telescope with a PrimaluceLab Esatto electronic focuser and converted from a traditional guide scope to an off-axis guider.

Engineering Note

Rear-end connection distance vs back focus

Although these terms are often used interchangeably within the astrophotography community, they’re not the same thing.

Traditional refractors and corrected Newtonians frequently require a fixed back focus behind the corrector or field flattener to achieve optimum performance.

The SCA310 instead provides a supported rear-end connection distance between 38 mm and 66 mm, allowing greater flexibility when configuring the imaging train. Throughout this review I’ll use SharpStar’s own terminology, as it more accurately reflects the design of the telescope.

Official Technical Specifications

The following specifications are taken directly from SharpStar’s published documentation.

SpecificationValue
Optical DesignSuper Cassegrain Astrograph (SCA)
Aperture310 mm
Focal Length1178 mm
Focal Ratiof/3.8
Primary MirrorAspherical
Secondary Mirror184 mm Fused Silica
CorrectorThree-element corrector incorporating one ED element
Corrected Image Circle55 mm
Optical Tube MaterialCarbon Fibre
Tube Length721 mm
Tube Diameter378 mm
Gross Weight23.5 kg (including rings, handle, dovetail and corrector)
Rear-end Thread OptionsM68, M54 and M48
Rear-end Connection Distance38–66 mm

On paper, these figures are certainly impressive, but specifications only tell part of the story.

The real question is how all of this translates into day-to-day use under the night sky.

After unpacking the telescope for the first time, that was exactly what I was about to find out.

First Impressions – Out of the Box

After waiting more than four years, finally opening the box was a mixture of excitement and relief.

There’s always a slight apprehension when you’ve built something up in your mind for so long. Expectations inevitably become high, and you start to wonder whether reality can ever live up to them.

Thankfully, the SCA310 made an excellent first impression.

The telescope arrived extremely well packaged, with every component securely protected for transport. Given both its size and weight, this immediately inspired confidence that SharpStar had put considerable thought into ensuring it would survive the journey intact.

The first thing that struck me wasn’t the weight—it was the physical size.

Photographs simply don’t prepare you for just how imposing the SCA310 is. Even after using the 20032PNT for several years, the increase in scale is immediately obvious. The larger tube diameter, substantial front corrector assembly and overall proportions make it clear that this is a serious piece of equipment.

The carbon fibre optical tube has a high-quality finish, while the CNC-machined components, tube rings and dovetail all feel reassuringly solid. Nothing feels lightweight or over-engineered for appearance alone. Instead, everything appears to have been designed with one goal in mind: providing a rigid platform capable of supporting the heavy imaging equipment that modern astrophotography demands.

One feature I particularly appreciated was the generous range of rear connection options. With M68, M54 and M48 adapters supplied, SharpStar has clearly considered the wide variety of cameras and accessories used by today’s astrophotographers. Rather than immediately reaching for custom adapters, most users should find it straightforward to begin assembling their imaging train.

The supplied focuser also deserves a mention. Although, as you’ll see later in this review, I eventually replaced it with a PrimaluceLab Esatto electronic focuser, my decision wasn’t because there was anything fundamentally wrong with the original. My imaging system is permanently mounted in the observatory and designed for fully automated operation, so upgrading to the Esatto was more about increasing rigidity and integrating with the rest of my observatory than correcting a weakness in SharpStar’s design.

Before attaching a camera or taking the telescope outside, I spent some time carrying out a thorough inspection. I always prefer to understand a new telescope mechanically before attempting first light. Checking the mirror cell, examining the rear cooling arrangement, familiarising myself with the adjustment points and planning the imaging train often saves time later on.

It was during this initial inspection that I started thinking about the cooling system.

The supplied arrangement is perfectly functional and undoubtedly adequate for most users, but as I looked at the airflow path through the telescope, I began wondering whether there might be a more effective way of managing the thermal behaviour of such a large primary mirror.

That thought stayed with me over the following days.

In the end, it became the very first modification I made to the telescope—and, looking back, it’s probably the modification that has had the greatest long-term impact on both usability and performance.

Owner’s Tip

Before making any modifications to a new telescope, spend some time getting to know how it’s been engineered. Understanding why a manufacturer has designed something a particular way makes it much easier to decide whether a change is genuinely an improvement or simply a different approach. In the case of the SCA310, living with the telescope for a short while confirmed the areas I wanted to refine, rather than changing things simply for the sake of it.

With the telescope inspected, the imaging train beginning to take shape and first light still ahead, it was time to tackle the one area I believed could be improved: the cooling system.

To be continued……………………………….Part 2

Equipment, Gear Reviews

Why I Trust the Primaluce Lab Eagle5 Pro to Power My Astrophotography Nights

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If you’ve ever spent a clear night under the stars watching a progress bar instead of gathering photons, you’ll understand the frustration that comes with building an astrophotography rig from disparate parts. Drivers fail to load, power distribution becomes a nightmare, cables become tangled or fail, and syncing your software suite across different machines can drain your patience—and your precious imaging time.

I’ve been there. Like many astrophotographers, I tried the “build it yourself” route: mini PCs from brand X, power hubs from brand Y, USB hubs from brand Z, and a jumble of cables trying to hold it all together. Every component technically worked… just not always at the same time. And not always reliably. Add to that the British weather windows we deal with, and wasting a night due to a system glitch just isn’t acceptable.

Enter the Primaluce Lab Eagle5 Pro.

Out of the Box: A Breath of Fresh, Italian-Engineered Air

From the moment I unboxed the Eagle5 Pro, the difference in approach was clear. Everything about it feels like it was designed by someone who actually does astrophotography—because it was. It’s not just a mini PC slapped into a box; it’s a purpose-built control hub engineered specifically for demanding astro workflows.

Installation was as straightforward as it gets: mount it on the telescope (it fits beautifully in the imaging train thanks to its low profile and rail system), connect power and data cables, and power on. No fiddling with BIOS settings, no sketchy Windows updates. Just boot, install your preferred imaging software and drivers for your equipment, and go.

In my case, the Eagle5 Pro controls:

  • ZWO ASI6200MM Pro camera
  • Sky-Watcher EQ8 Pro mount
  • Talon Roll-off Roof observatory automation
  • Filter wheel, focuser, dew heaters, guide cam, and all the usual suspects

Everything talks, everything syncs, and everything just works.

Total System Integration

This is where the Eagle5 Pro truly shines. Not only does it run your software stack (NINA, Sequence Generator Pro, or whatever you use), but it also manages power distribution, USB ports, WiFi/Ethernet connectivity, and environment monitoring, all in one device. You can schedule power-ups for each component individually, monitor voltage and current draw in real time, and reboot USB ports remotely—without crawling around your observatory in the dark.

The bundled EAGLE Manager software ties it all together, giving you a clean dashboard to control everything—from your main imaging camera to your dew heaters—on a single screen.

Compare that to the DIY route where power comes from one source, USB control from another, and networking from somewhere else entirely. The second something glitches, you’re in a digital detective story trying to track down what failed. With the Eagle5 Pro, it’s unified. It’s visual. It’s intuitive.

No More Lost Nights

I haven’t lost a single night to hardware or software troubleshooting since switching to the Eagle5 Pro.

Let me say that again: not one.

When the weather gives me a green light, I know my gear will perform. That peace of mind is priceless. No more last-minute reboots, mysterious ASCOM issues, or power ghosts causing reinitialization loops. My ASI6200 fires up cleanly every time, the EQ8 Pro slews and tracks without drama, and the roof opens and closes as scheduled.

In an era when we’re all chasing photons between the clouds, stability is not a luxury—it’s a necessity.

Final Thoughts

If you’re on the fence about the Eagle5 Pro, ask yourself: how much is a single night of imaging worth to you? Now multiply that by all the nights you’ve lost to troubleshooting. The Eagle5 Pro may look like a premium investment upfront, but it pays for itself every time it lets you image instead of debug.

Equipment, Informational

The CCD vs. CMOS Showdown: Why Monochrome Cameras Excel in Astrophotography Over One Shot Color

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Introduction
One of the first things photographers must decide when venturing into astrophotography is what kind of camera sensor they’ll need to capture the beauty of the cosmos. Charge-Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS) image sensors are two of the most common on the market (CMOS). Each has its own set of pros and cons that make it better or worse for astrophotography in certain situations. Further complicating matters is the ongoing discussion between advocates of monochrome and one-shot colour cameras.

Understanding CCD and CMOS Sensors
Light is converted into electronic signals by the CCD or CMOS sensor at the centre of a digital camera. The image quality, cost, and power consumption are all impacted, but in fundamentally different ways.

CCD Sensors
CCDs have been the go-to sensors for astronomy photography for quite some time. They are well-known for the exceptional clarity and sensitivity to light of their photographs. These sensors generate low-noise, high-quality images by transferring charge across the chip and converting it into voltage in a single spot: the array’s corner. In turn, this improves light collection by allowing for a greater pixel fill-factor. CCDs, on the other hand, are typically more costly and power-hungry than their CMOS counterparts. In addition, they experience ‘blooming,’ an effect in which overcharged pixels leak their energy into neighbouring ones.

CMOS Sensors
In contrast, CMOS sensors have shorter processing times and use less power because light is converted to voltage right at each pixel’s location. They have lower manufacturing costs, making them common in smartphones and consumer-grade cameras. Their read noise and sensitivity are typically higher than that of CCDs, though. Recently developed technologies have allowed CMOS sensors to catch up to and even surpass CCDs in terms of performance, closing the gap between the two.

Monochrome vs. One Shot Colour Cameras
After settling on a CCD or CMOS camera, the next big decision in astrophotography is whether to use a monochrome or one-shot colour camera.

One Shot Color Cameras
As the name implies, a One Shot Color camera takes a complete colour picture with just one click of the shutter. The Bayer mosaic used in these cameras covers each pixel with red, green, and blue filters. The greatest benefit of these cameras lies in their ease of use. Even amateur astronomers can easily take stunning, colourful pictures of the night sky with these instruments.

Monochrome Cameras
Images taken with a monochrome camera are grayscale. These cameras capture red, green, and blue light through individual filters and combine them into full colour in post-production. Even though using a monochrome camera is more difficult and time-consuming, there are some benefits.

Why Monochrome Cameras Excel in Astrophotography
In general, monochrome cameras have higher sensitivities than single-shot colour ones. They are up to three times as sensitive as cameras that use a Bayer filter because all of the light that reaches the sensor is used to create the image. This heightened sensitivities is especially helpful in low-light astrophotography.

Additionally, more options and control can be had during the imaging process when separate filters are used with a monochrome camera. Using a hydrogen-alpha filter, astronomical photographers can isolate and emphasise specific wavelengths of light, such as the ionised hydrogen regions in nebulae. Imaging in light-polluted skies or capturing narrowband images greatly benefits from this ability.

Because the information for each colour channel is captured by the entire sensor rather than just a subset of pixels, as in one-shot colour cameras, the resulting images have greater resolution and detail.

Conclusion
In conclusion, CCD and CMOS sensors each have their uses in astrophotography, and the one you settle on will depend on your particular goals, financial constraints, and level of experience. Comparing monochrome and one-shot colour cameras, the former has better sensitivity, flexibility, and resolution while the latter is more user-friendly and saves time. Therefore, the investment in a monochrome camera and separate filters can be well worth it for serious astrophotographers seeking to capture the highest quality images.

Equipment, Gear Reviews, Informational

Sharpstar 20032PNT F3.2 Paraboloid Astrograph Review

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Having owned the Sharpstar 15028HNT, I decided I wanted a larger light bucket without really sacrificing on speed, so I opted for the big brother of the 15028HNT which is the SharpStar 20032PNT.

I picked up my 20032PNT from Zoltan at 365Astronomy, and could not wait to get it home and unbox it, so after removing it from not just one carboard box, but two, I was presented with a very large flight case, which evidently is a larger version than the one that came with the 15028HNT.

Once I had the scope unpacked and inspected everything, the first thing I noticed was the focuser, the 20032PNT has a large focuser, which is big enough to accomodate the reducer/corrector that has an M68 connector thread as well as an M54 and an M48 connector thread.

The scope is well built, as I would expect from the build quality of the 15028HNT, the red annodised alluminium tube rings just give that final touch of finese. The 3 inch focuser is very smooth, and will no doubt be able to handle quite a load of equipment.

The first thing I planned to do was ensure that the primary mirror was secure and did not rock back and forward as well as replace the stock fan. I have fed back to SharpStar that they should mount the fan externally and also mount it with shock absorbing rubber mounters, and have the airflow into the tube from the back, rather than drawing air down the tube from the secondary. Here are my images of the fan replacement:

Primary Mirror assembly removed from OTA
Fan assembly with mirror removed
Stock Fan

Stock fan removed and added in a PWM fan connector should the fan ever need to be replaced, it can be replaced without removing the mirror assembly
Anti vibration fan mounting points
External fan connected to PWM connector
How the fan looks from the outside, the image is missing the fan filter which I added afterwards

Once everything was back together, I mounted my Eagle4Pro onto the top bar, as well as added an extra long losmandy plate because I wanted the OTA as far forward as I could get it in order to have the camera in the right location without it hitting the mount at all.

And here is the scope on the mighty EQ8 Pro mount

My first set of image testing did not go so well. My previous 15028HNT did not protrude above the walls of the observatory, so despite the fact that the secondary mirrors on both scopes are right up at the top of the tube, the 20032PNT was picking up stray light from my neighbour, so I had to adopt a dew shield that would extend the OTA by around 5 inches:

Scope with dew shield attached

Flats
I first started to have issues with my flats that was taken with a flat panel, the flat frames would “Overcorrect” the images, but one thing I noticed that there was a lot of vignetting happening. Sky flats seemed to work better, but I was not happy with the vignetting. Now since I am using a full frame sensor on the ASI6200MM Pro, and the scope supports full frame, I was a little intrigued as to why I was getting so much vignetting, you can see from the master flat below that there was indeed a significant amount of vignetting.

Red Master Flat in PixInsight

I did some calculations and found what my problem was. Since my camera is full frame, it has a diameter of 44mm. The M54 connector on the telescope is 55mm away from the sensor, so a simple equation tells me that my light cone is larger than the M54 connector:

Sensor diameter + (distance from sensor / focal ratio)
44 + (55/3.2) =61.1875mm

The internal diameter of the M54 connector is around 51mm, so the light cone was being restricted by around 10mm. So I had a custom M68 to M54 adapter made which is 28.5mm in length, the reason for this is because the backfocus from the M68 connector is 61mm, so if we apply our formula:

44 + (61/3.2) = 63.06mm, this is way below the internal diameter of the M68 connector male thread, so vignetting should be minimised. Now because I do have some M54 in my image train, I know I would not completely elliminate vignetting and this is why, using the above formula, we can work out the light cone at varying part of the imaging train:

12.5mm (EFW mating to camera) = 47.9mm
18mm (50.4mm Filters distance from sensor) = 49.62mm
32.5mm (Light entrance to EFW distance from sensor) = 54.15mm

As you can see, I should expect some vignetting to occur because the light cone at the EFW M54 connector (with around 51mm internal) is 54.15mm, so I would be clipping the light cone slightly, but the result is as follows, again red filter, you can see that the vignetting is significantly reduced:

Collimation was done using the exact same process I used on the 15028HNT, you can read the guide here.

Conclusion:
SharpStar have again produced an outstanding quality astrograph, with a massive focuser to take on the largest of imaging trains, as well as finishing off the product with high quality annodised OTA rings. I am extremely happy with the performance of the telescope, below is my first image which happens to be a 2 panel mosaic:

Iris Nebula, 2 Panel Mosaic, Each Panel consists of 151x60S frames at Gain100, for L, R, G and B, for the full resolution image please use this link

Backfocus information:
M42 connector: 53mm
M54 connector: 55mm
M68 connector: 61mm

Focal Length (With Reducer/Corrector): 640mm
Focal Ratio: F3.2
Newtonian Type: Paraboloid
Focuser Size: 3″

The only complaint I have is with regards to the fan, which I have made a suggestion to SharpStar on that. Good job again SharpStar!

Equipment, Gear Reviews

ZWO ASI6200 62mpx Full Frame Camera Review

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I recently wrote a review on the ZWO ASI2400 24mpx full frame camera, so I thought I would also do the same for the big brother which is the ZWO ASI6200 full frame camera with a mammoth 62mpx which I picked up from 365astronomy when returning the ASI2400 after the review. Looking at both of the cameras, there is no obvious difference from the outside except for the model number, both cameras are exactly the same size and feel roughly the same weight and the build quality is identicallyu exceptional.

ASI6200MC Pro One Shot Colour Camera

If we compare the specifications of the ASI6200 to the ASI2400 we can see where each camera has an advantage over the other:

ASI2400ASI6200
Weight700g700g
SensorIMX410IMX455
Sensor SizeFull FrameFull Frame
Pixel Size5.94um3.76um
Resolution24mpx62mpx
Full Well Capacity at 0 Gain100ke51ke
Qe>80%91%
ADC14-Bit16-Bit
High Gain Mode140100
Full well at High Gain Mode20ke18ke

So as you can see from the comparison on specification there are some differences, the ASI2400 has the edge on full well capacity, however the ASI6200 has a much more smaller pixel size as well as a higher Qe which to me gives the ASI6200 the edge over the ASI2400.

Now since both cameras are the exact same field of view due to them both being full frame sensors, the question is how does this affect resolution, clearly the ASI6200 has the upper hand having significantly more pixels than the ASI2400, but how does this translate to an image?

Iris Nebula taken with the ASI2400MC Pro, 82x150S at Gain 26, darks, flats and BIAS frames applied
Iris Nebula taken with the ASI6200MC Pro 48x150S at Gain 100, Darks, Flats and BIAS frames applied

As you can see, both cameras offer the exact same field of view, however when you zoom in on the images you start to see where the ASI6200 excels above the ASI2400 with the higher resolution

On the left is the ASI2400MC Pro and on the right is the ASI6200MC Pro

As you can clearly see from the above two images, the 6200 offers a much better resolution which will allow a much finer level of detail, however, depending on your sky conditions and focal length the ASI6200 might not be possible due to over or under sampling

You can see here, that on my SharpStar 15028HNT which has a Focal Length of 420mm the ASI2400 would lead to Under Sampling in my “OK” seeing conditions

But the ASI6200 shows in the green area:

If I increase the focal length to around 1150 the ASI6200 no longer becomes suitable and the ASI2400 is more suited to this focal length and sky conditions:

So as you can see, both the ASI2400 and ASI6200 is not a “One Size Fits All” scenario, you have to work out the best suitability depending on your conditions and equipment to be used.

From a price perspective, the ASI6200 is only slightly more expensive than the ASI2400, but both cameras offer the full frame capability and a fantastic field of view, but for me personally the ASI6200 beats the ASI2400 when using the focal length of my SharpStar 15028HNT. Just like it’s smaller version, the looks, feels, sounds and operates exactly the same way. Here is another image taken with the ASI6200 and then my Synthetic SHO version which I will be writing a tutorial on how to acomplish with Dual Band Filters.

North America Nebula – 60x300S at Gain 100 using the Optolong L-eXtreme Filter on the SharpStar 15028HNT
Synthetic SHO using the same data as the previous image

Either way, both ZWO cameras I have tested have been of awesome quality, and I would recommend either camera if you wish to go down the full frame route, but personally my favourite is the ASI6200MC Pro, more images to come since this is now my new camera.

Equipment, Gear Reviews

ZWO ASI2400MC Pro Full Frame 24mpx camera review

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I was lucky enough for 365Astronomy to offer me one of the ZWO ASI2400 full frame cameras to test and write a review, so obviously I jumped at the chance, and within a couple of days I was successfully imaging and acquiring data with it, so firstly what is the ASI2400?

The ASI2400MC Pro is a full frame 24mpx camera that utilises the Sony IMX410 back illuminated sensor, ZWO produced a similar camera before which was the ASI128MC Pro (24mpx) and they also have the ASI6200 (62mpx), so what are the differences between the cameras?

ASI2400MCASI128MCASI6200MC
Image SensorIMX410IMX128IMX455
Pixel Size5.945.973.76
Full Well Capacity100ke76ke51.4ke
Cooling Delta-35C-35C-35C
Resolution6072×40426032*40329576×6388
ADC14-Bit14-Bit16-Bit
Read Noise1.1e-6.4e2.5e1.2e-3.5e
DDR Buffer256MB256MB256MB
QE >80%>53%>80%
FPS (Video)852

If we compare the ASI2400 and the ASI128 since they have similar pixel sizes and offer almost a matching resolution, but the ASI2400 clearly is a better camera, with a higher full well capacity, this means that it takes a lot more to saturate out the colours around bright stars for example, but also a big increase on the quantum efficiency going from 53% to >80%.

Now the first thing I noticed was that the ASI2400 was only slightly cheaper than the ASI6200, but the ASI6200 is offering a much higher resolution, so why would people not just go for the ASI6200? Well it comes down to pixel size, the ASI6200 has a pixel size of 3.76 so it would be better suited to a short focal length scope, if I attach the ASI6200 to my SharpStar 15028HNT which has a focal length of 420mm at F2.8, this will give me around 1.85 Arc-Seconds per Pixel which for UK skies is an ideal figure, the ASI2400 has a bit more flexibility with the focal length of telescopes because of the larger pixel size, so whilst the ASI6200 offers a higher resolution image sensor of 62mpx, the ASI2400 offers more flexibility of a higher focal length telescope.

When I unboxed the ASI2400 I was very impressed with the quality, this was the first ZWO Camera I have ever actually seen in the flesh, the red finish matches my SharpStar 15028HNT, but one thing that I noticed straight away was the two additional USB Ports on the top of the camera which I sat and thought to myself that it would certainly help with tidying up my cables around the scope. In the box was a couple of adapters to obtain the very common 55mm back focus, two USB Cables, and a USB 3.0 cable, and the camera arrived in a very nice case too.

I removed the camera sensor cover and revealed the massive full frame sensor and compared it to the APS-C sized camera I have and was like wow, that’s a big sensor, here’s a picture of the sensor:

Size matters, the Full Frame sensor on the ASI2400MC Pro

I noticed too that there was a special tilt plate on the camera which in my opinion is a critical point, my other camera has a tilt plate that is very cumbersome to use, so after a while of looking at the sensor, I decided to start adding my ZWO filter drawer and M48 extension tubes in order to get it connected to the mount, I am using the ZWO M54 2″ Filter drawer which has a 2mm M54 to M48 adapter too, threading the filter drawer on the camera was very smooth, but I would not expect anything less than that with ZWO kit connecting to ZWO kit, here’s a picture with the filter drawer and the Optolong L-Pro 2″ filter connected to the camera:

ZWO M54 Filter Drawer connected to the ASI2400MC Pro

Once connected to the telescope, I had to find out where the camera was facing when connected at the optimal distance of 55mm as all of my image train is threaded on, once identified which direction the top of the camera sensor was facing I could rotate the focuser and then re-check the collimation with the laser before putting the camera back on and connecting the cables.

Identifying which side of the camera the top of the sensor was is so easy on this camera, there’s what looks like a black plastic button on the side of the camera, it is obviously a cover of some sort, but this also indicates which side the top of sensior is located, something I wish all camera vendors would do.

One of the first things I do when testing out a new camera is dark frames, all vendors claim they have zero amp glow, so this is always my first test, and the ASI2400 didn’t let me down, indeed there was zero amp glow and I tested with various exposure times and gain settings, here’s a 300S exposure with Gain 26 which has had a Screen Transfer Function auto stretch applied:

After connecting it all up to the telescope, and acquiring some darks, flats, and BIAS frames, and the skies were clear, it was time to put the camera under a proper test, I had set a couple of targets up, the Cygnus Loop and the Elephant’s Trunk Nebula using the Optolong L-eXtreme Narrowband filter and here are the results:

Cygnus Loop – Eastern Veil, Western Veil and Pickerings Triangle – 29x300S at Gain 26, ASI2400MC Pro on the Sharpstar15028HNT using the Optolong L-eXtreme Dual Band Filter
Elephant’s Trunk Nebula – 19x300S at Gain 26, ASI 2400MC Pro on the SharpStar 15028HNT using the Optolong L-eXtreme Dual Band Filter

So you can see the camera performed really well, stars are almost perfect in the corners (a little fine tuning required on spacing), I am hoping to get a few more clear nights over the next few days to build on the above images and really show off the performance of the ASI2400, and I can’t wait to test it out on the Iris Nebula.

Conclusion:
The ASI2400 is in my opinion an awesome piece of kit, that massive full frame sensor has the adaptability for longer focal length telescopes due to the larger pixel size, the advantage of the USB Hub built into the camera, the adjustable tilt plate on the front of the camera is the most advantageous aspect, would have saved me so much time trying to rectify tilt instead using copper shims, but also the smaller things that are equally as important like having something to identify which way round the sensor is rather than trying to figure it out with images in my opinion is what sets this apart from other similar cameras from other vendors.

If you are looking for a full frame camera and have a short focal length telescope, the ASI2400 or the ASI6200 full frame cameras will do just the job,but any longer focal length scopes, then the ASI2400 is the right choice.

Additional image taken since writing this post:

M31 – Andromeda Galaxy – 51x90S frames at Gain 0 using the Optolong L-Pro Filter, darks and flats applied
Equipment, Gear Reviews

QHY268C APS-C Colour Camera Review – Part 1

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As many of you know, I have been using QHY cameras for a while, but with my plan to move to a RASA telescope next year and wanting to image with a bigger sensor than the QHY183M I decided to go for a bigger sensor but moving away from Mono, the latest addition to the QHY familly is the QHY268C Photographic Version. I had been talking to the QHY team for a long time about this particular camera, and finally I have one.

The QHY268C is a once shot colour camera based on the APS-C Sized back illimunated Sony IMX571 sensor, the camera has a true 16-Bit Analog to Digital Convertor (ADC), now there are a few camera models out there using this sensor, cameras such as the ZWO ASI2600, but one thing that sets the QHY268C apart from the others is the ability to have a 75ke full well capacity which is 25ke higher than the ZWO ASI2600. In my opinion, when imaging at fast focal ratios, a higher full well is desired to protect the colour around bright stars for example.

Opening the box I was greeted with a camera that was bigger and heavier than my 183M, but then the sensor is much bigger than the 183M anyway so this would be expected, but what I did not expect is the additional items that came with the camera:

Inside the box was:

  • QHY268C Photographic Version
  • UK mains plug for 12V AC adapter
  • 12V AC adapter
  • Car 12v power cable
  • Self locking power cable
  • 1.5M USB 3.0 cable
  • Dessicant drying tube
  • Self centering adapter plate
  • M54 to M48 adapter plate
  • M54 to 2″ nose adapter
  • A range of spacers to give you from 0.5mm to 13.5mm spacing
  • Associated screws for spacing adapters

QHY cameras have come along way since I bought my QHY183M, one of the things QHY has really worked on is amp glow, my early version of the QHY183M was renowned for was amp glow, which could be removed in image calibrations, but the QHY268C produces no amp glow whatsoever, below is a dark frame of 600S taken at -13.5C and you can clearly see there is no evidence of amp glow.

Single frame 600 seconds, Gain 26, Offset 30, -13.5C – Mono (Not Debayered)

Attaching to the telescope was pretty straight forward as I had already planned the imaging train before the camera arrived, since I will be using the SharpStar 15028HNT F2.8 Paraboloid Astrograph which has an M48 thread, I decided to keep the whole imaging train at M48 except for the camera of course which has an M54 thread, so I did not actually need to use any of the adapters that came with the camera, the reason for this is because I wanted to include a filter drawer, so my image train consists of the following (from telescope to camera)

  • TSOAG9 – TS Off Axis Guider (9mm)
  • TSOAG9-M48 – TS M48 Adapter for the OAG (2.5mm)
  • TSFSLM48 – TS 2″ Filter Drawer with M48 Thread (18mm)
  • M48AbstimmA05 – TS Optics 0.5mm Aluminium spacing ring (0.5mm)
  • TSM54a-m48i – TS M48 to M54 Adapter (1.5mm)
  • QHY268C with M54 Centering Adapter (23.5mm)

As you can see with all the above I reach my desired back focus of 55mm perfectly, if I was not going to be using a filter drawer (For my Optolong L-Pro and L-eXtreme filters), I would probably have stuck with the spacers that came with the camera. Below is a picture of the camera successfully connected to the telescope.

As far as settings go, after speaking with QHY on this at great length, I will be imaging in Mode 0 (Photographic mode) to avail of the massive 75ke full well, offset I will leave at 30, but Gain I will use two different settings, I will use Gain 0 for most bright objects with the L-Pro filter, but for the L-eXtreme, I’ll probably set a gain level of 26, luckily with SGPro I can set the gain level per object. From a cooling perspective I always image at -20C, one thing I have noticed is that this camera cools to exactly -35C below ambient, I tested this when the ambient temperature was 20.10 degrees, and the camera cooled down to -14.9C, it was always 25C lower until the ambient dropped below 15C and the camera remained at my setting of -20C.

The build quality of the camera is as expected having owned a QHY183M, one thing I did notice is that the fan in the QHY268C is much quieter than the 183M. Technical Details of the camera:

CameraQHY268CQHY183M
Image SensorSony IMX571Sony IMX183
Sensor SizeAPS-C1″
IlluminationBack IlluminatedBack Illuminated
Pixel Size3.76um2.4um
Effective Image26mpx20mpx
Full well capacity51ke
(75ke in extended mode)		15.5ke
ADC16-Bit12-Bit
Image Buffer Memory1GB/2GB128MB
Max Cooling Delta-35C-40C
Weight1006g650g

I can’t wait to get imaging with this camera, I have a very aggresive target list for this year in both RGB and Narrowband with the Optolong L-eXtreme filter, I will write part two of the review once I have some actual imaging data. Time to build my dark library.

Equipment, Gear Reviews

SharpStar 15028HNT

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After months of trying to get my trusty Sky-Watcher Quattro F4 to work with the ASA 0.73x reducer I decided to go all in on an F2.8 astrograph. After doing some research I stumbled across the SharpStar 15028HNT F2.8 Hyperboloid Newtonian Reflector from my local supplier 365Astronomy.

After toying with the idea and speaking to my good friend Nick from Altair Astro and with the idea of going back to a refractor, I decided that I could not go back to slower than F4 and I wanted something that in essence would work with a bigger sensor than my QHY183M, and the Sharpstar looked like it could work for me, so I placed my order with Zoltan from 365Astronomy and collected it the following day.

Unboxing the scope, I was like a young child at christmas, the scope came with a very sturdy protective hard case and removing the scope out of the case you could immediately feel that a lot of time and effort had gone into producing the 15028HNT.

Aperture: 150mm
Focal Length: 420mm
Focal Ratio: F2.8
Weight: 6kg
Tube Material: Carbon Fiber

With the scope unboxed I started to fit my equipment onto the scope. In order to fit my Sesto Senso I had to rotate the focuser 90 degrees clockwise due to the telescope mounting rings, this is when I noticed an isue that one of the grub screws on the focuser would not tighten and I needed to stop the backlash, fortunately there’s another grub screw on the other side that tightened and stopped the backlash.

Before I attached my imaging equipment, I had to ensure that the telescope was collimated, so I stumbled across the collimation guide which after speaking with my good friend Terry Hancock over at Grand Mesa Observatory who was also evaluating the same scope, we both agreed that the colimation guide wasn’t very well written as it mentioned nothing about collimating the primary. One thing that it mentioned is to remove the corrector, Sharpstar include a tool for you to remove the mounting plate and corrector, but here is a word of advice……..remove this when the telescope is cold, take that advice from someone who tried to remove it whilst it was warm!

I performed a laser collimation with my Concenter Eyepiece to check the secondary, and then a laser to check the primary, now the collimation guide says to remove the corrector, I have done validation with both the corrector removed and the corrector in place, and it made no difference whatsoever, so my opinion is to leave the corrector in place.

With the scope closely collimated, I mounted my StarlightXpress Filterwheel and Camera which with the 15028HNT is an M48 thread for the gear to screw onto.

I will post some images as soon as I have completed some, the weather has been pretty poor (probably because I bought a new scope), but the frames I have got so far are very sharp, pinpoint and I can honestly say I have never seen images come directly off the camera so sharp.

My field of view with the QHY183M is around 1.21 Arcsec/Pixel which gives me a FOV or around 1.81°x1.2° and I love the difraction spikes being at 45 degrees compared to the 90 degrees on the skywatcher and I already have a pretty full target list for this scope ready to go this season.

Apart from the couple of product issues I have experienced (Grub screw on focuser and tube clamp thumbscrew being threaded) I am extremely happy with the scope, it is performing really well and here are a couple of work in progress images that I have started

Dark Shark Nebula Moscaic Panel 1 – 51x300S in Red, 25x300S in Green and Blue
Elephant’s Trunk – 51x300S in 6nm Ha
M45 – Mosaic Panel 1 – 12x150S in R, G and B

After a few weeks, the telescope has held collimation very well, I have not had to perform any re-collimation, I will re-evaluate this in the much colder months of winter.

I am so happy with the scope that I am actually considering a second one for an OSC Camera with a bigger sensor.

Equipment, Gear Reviews

The source to the halo around bright stars

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When I moved to the Sky-Watcher Quattro telescope I noticed some bizzare halo’s around bright stars in my images, this was evident in both my Atik 383L+ CCD Camera as well as my QHY183M ColdMOS Camera when using the Quattro 8-CF at F4, if you browse my galleries you will see what I mean, and it was more noticable in my Narrowband images. Below is one of my recent images where you can see the halo around Magnitude 3.9 star 15 Mon in the Christmas Tree Cluster / NGC2264.

I contacted Baader back in February 2019 since all of my filters were Baader, and I noticed that the Halo was present in all of my filters but significantly less in Red, but more prevalent in Narrowband filters, so the logical cause would be the filters. Baader immediately dismissed this to be the fault of their filters and suggested that my Coma Corrector be the root cause.

Not convinced that the Coma Corrector was causing the issue, I did some research online and came across a brilliant page on the Astronomik website where they claim to have resolved the majority of the Halo issue, and after reading the following line from the page I was convinced the filters were my issue:

In recent years very fast optical systems have become popular for imaging. The energy in a filter induced halo grows exponentially as the f-ratio decreases. Additional to this, the smaller the FWHM band pass of the filter, the stronger the halo.

The above line described my issue perfectly so I mentioned this to Baader who again dismissed the possibility of it being their filters and again put the blame firmly to my optical train. Again not happy, I contacted Astronomik and Eric emailed me back very promptly and offered to send me out one of their 6nm Ha filters to test. A few days ago the filter arrived and I was able to perform some testing against the Baader filter also for comparison on the same star.

Since the star in my image above was of magnitude 3.9, I wanted to find something similar, so I found star Alhaud VI and proceeded to obtain 15x300S Exposures for each filter, and here are the results:

Astronomik 6nm HA filter, 15x300S with Darks and Flats applied
Baader 7nm Ha filter, 15x300S with Darks and Flats applied

So as you can see the Baader filter shows a high amount of Halo around the bright star and the Astronomik filter does not, now if this was something to do with the rest of the optical train there would be evidence in the Astronomik filter also.

Now I agree there will be some reflection in the optical train, all that glass in the coma corrector, the glass on the camera etc, so I thought I would have a look at both images in a bit more detail, zoomed in on the stars there is what appears to be a slight halo in the same place on both images:

Astronomik 6nm Ha Filter
Baader 7nm Ha Filter

So both filters show the Inner Halo which in my opinion would not be visible in an image, but again clearly the Baader filter has some reflection issues happening as you can clearly see two additional Halos. The interesting thing about all three Halos is that the central one visible in both filters has no relationship to the distances between the other two in the Baader, however the two outer Halos on the baader are the same distance apart as the middle halo is from the star, so clearly this is some sort of reflection.

Conclusion:
Astronomik have done a fantastic job at eliminating Halo artifacts around bright stars, clearly the Baader filters are causing major Halo artifacts because if this was the optical train then it would be evident in the Astronimik filters also, I suspect that the Baader filters are not optimised for faster focal ratio imaging systems. I have provided this information to Baader and await a response from them.

Good job Astronomik Filters