Tag Archives: SHO

Creating a Hubble Palette Image from OSC Dual Band Data

Many people like myself have transitioned from a MONO camera to a One Shot Colour (OSC) for whatever reason, for me it was all about not being able to get the required amount of time due to weather conditions here in the UK. When I first considered moving to an OSC camera, it dawned on me that I would not be able to produce the vibrant Hubble Palette images that I could produce by imaging with specific filters on my MONO camera, specifically Hydrogen Alpha (Ha), Oxygen 3 (OIII) and Sulphur Dioxide 2 (SII) which would then be mapped to the appropriate colour channels when creating the final image stack.

Now along came Dual and Tri band narrowband filters for OSC cameras which peaked my attention, the Dual Band filters allow Ha and OIII data to pass, the Tri Band filters allow Ha, Hb (Hydrogen Beta) and OIII to pass but at a high Nm value. I reached out to my friends at Optolong who had two filters, the L-eNhance and the L-eXtreme, the L-eNhance is a Tri Band filter, but after speaking with Optolong it would not work well for me at F2.8, so I went with the L-eXtreme Dual Band filter which has both the Ha and OIII at 7nm.

After receinving my ASI6200MC Pro, I decided to start acquiring data on a 1/2 to 2/3 moonlit nights on the North America Nebula, and so far when writing this post I had acquired a total of 60 frames of 300 seconds each at a gain value of 100, I processed the image my normal way in PixInsight and below is the result of the image:

North America Nebula, 60x300S @Gain100, Darks, Flats and BIAS frames applied with the ASI6200MC Pro using the Optolong L-eXtreme Dual Band 2″ Filter

I thought that my data looks good enough to work with and experiment with trying to build an SHO (Hubble Palette) image with, and I have spoken with Shawn Nielsen on this exact subject a few times so he gave me some hints and tips especially with the blending of the channels. So off I went to try and produce an SHO image.

Before we start, there are some requirements:

  • This tutorial uses PixInsight, I am not sure how you would acomplish this with Photoshop since I have not used PhotoShop for Astro Image Processing for a number of years
  • Data captured with a One Shot Color (OSC) camera using a Dual or Tri Band Narrowband filter
  • Image is non-linear…so fully processed

Step 1 – Split the Channels

In order to re-assign the channels, you have to split the normal image into Red, Green and Blue channels, I found this to work better on a fully processed “Non-Linear” image as above, once this was done, I renamed the images in PixInsight to “Ha” – Red Channel, “OIII” – Blue Channel and “SII” – Green Channel, this makes it easier for Pixelmath in PixInsight to work with the image names. Once this was done, I used PixelMath to create a new image stack with the channels assigned, and this is how PixelMath was configured

Red Channel = SII
Green Channel = 0.8*Ha + 0.2*OIII
Blue Channel = OIII

Once applied this produced the following image stack (do not close the Ha, OIII or SII images, you will need these later on):

SHO Combined image from PixelMath

Step 2 – Reduce Magenta saturation

As you can see from the above image, some of the brighter stars have a magenta hue around them, so to reduce this, I use the ColorMask plugin in PixInsight (You will need to download this), and selected Magenta

ColorMask tool with Magenta selected

When you click on OK, it will create the Magenta Mask which would look something like this:

Once the mask has been applied to the image, I then use Curves Transformation to reduce the saturation which will reduce the Magenta in the image


The result in reducing the magenta can be seen in this image, you will notice there is now no longer a hue around the brighter stars

Result after Magenta Saturation reduced using Magenta ColorMask and Curves Transformation

Step 4 – ColorMask – Green

Again using the Color Mask tool, I want to select the green channel, as we will want to manipulate most of the green here to red, so again ColorMask:

This then produced a mask that looks like the following:

Step 5 – Manipulate the Green Data

Once the Green Mask has been applied to the image, since most of the data in the image is green, we are looking to manipulate that data to turn it golden yellow, so for this we use the Curves Transformation again

The above Curves transformation was applied to the image three times whilst the the green mask was still im place, and this resulted in the following image changes:

Resulting image after green data manipulated in the red channel using Curves Transformation

So as you can see we are starting to see the vibrant colours associated with Hubble Palette images

Step 6 – Create a Starless version of the OIII Data

Now remember I said not to close out the separated channel images, this is because we are going to want ot bring out the blue in the image without affecting the stars, so for this we will turn the OIII image into a starless version by using the StarNet tool in PixInsight

Here’s the OIII Image before we apply StarNet star removal:

Default settings used in the StarNet process

This resulted in the following OIII image with no stars:

OIII Data with stars removed using StarNet Process

Step 7 – Range Selection on OIII Data

Because we do not want to affect the whole image, we will use the range selection tool on the starless OIII image to select areas we wish to manipulate, now we have to be careful that the changes we make are not too “Sharp” that they cause blotchy areas, so within the range selection tool, not only do we change the upper limit to suit the range we want to create the mask for, but we also need to change the fuzziness and smoothness settings to make it more blended, these are the setings I used:

Which resulted in the following range mask

Rangemask created using the RangeMask process

Step 8 – Bring out the Blue with Curves Transformation

We apply the Range Mask to the SHO Image so that we can bring out the Blue in the section of the nebula where the OIII resides, with the range mask applied we will use the Curves Transformation Process again as follows:

Curves transformation process to increase blue, reduce red and increase saturation of image with rangemask applied

The result of which is:

Result after first curves transformation with RangeMask applied

As you can see we have started to bring out the blue data, but we are not quite there yet, with the range mask still applied, we will go again with the curves transformation only this time, just reducing the red element:


The result of the 2nd curves transformation with the Range Mask is as follows:

Resulting image after 2nd pass with Curves Transformation to remove the red elemtn in the range mask

Step 9 – Apply Saturation against a luminance mask

On the above image, we extract out the luminance and apply as a mask to the image, and we then use the Curves Transformation for the final time to boost the saturation to the luminance

Luminance Mask to be applied to image
Curves Transformation with Luminance Mask applied

Final Image

I repeated the same process on my Elephant’s Trunk Nebula that I acquired the data when testing out the ASI2400MC Pro and this was the resulting image:

Elephant’s Trunk Nebula, 19x300S at Gain 26 on the ASI2400MC Pro with the Optolong L-eXtreme Filter using the workflow in this article

I hope this tutorial helps in producing your SHO images from your OSC Narrowband images, I know many of my followers have been waiting for me to write this up, so enjoy and share.

ZWO ASI6200 62mpx Full Frame Camera Review

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 Smapling 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.

IC36 Y Cas Nebula in SHO

Located in the constellation of Cassiopeia this rather feint nebula is illuminated by a very bright Magnitude 2.15 star Navi

Image Details:
101x300S in SII – Red Channel
101x300S in Ha – Green Channel
101x300S in OIII – Blue Channel

Total integration time: 25.2 Hours

101 Darks, Flats and Dark Flats applied

Acquisition Dates: Oct. 27, 2018, Dec. 13, 2018, Dec. 27, 2018, Jan. 1, 2019, Jan. 2, 2019, Jan. 4, 2019, Jan. 8, 2019, Jan. 9, 2019, Jan. 11, 2019, Jan. 18, 2019, Jan. 20, 2019, Jan. 23, 2019, Jan. 27, 2019, Jan. 28, 2019, Jan. 30, 2019

Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8″ F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium Ha, SII and OIII
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

NGC6888 – Crescent Nebula in SHO Narrowband

This object is a little tricker for me since I only have a 3-3.5 hour window per evening due to trees and the house blocking my view, this is also the first image that I used the drizzle function within PixInsight to be able to provide a detailed up close version of the image, I was very happy to have captured the brown “Globules” within the nebula to

Crescent Nebula in SHO Narrowband
Same object but with a 2x drizzle function in PixInsight applied

Image Details:
Red Channel – SII Data – 89x300S
Green Channel – Ha Data – 64x300S
Blue Channel – OIII Data – 109x300S

101 Darks, Flats and BIAS Frames used 

Equipment Used:-
Imaging Camera: QHY183M Mono ColdMOS Camera at -20C
Imaging Scope: Skywatcher Quattro 8″ F4 Newtonian
Guide Scope: Skywatcher Finder Scope
Guide Camera: QHY5L-II
Mount: Skywatcher EQ8 Pro GEM Mount
Focuser: PrimaluceLabs ROBO Focuser
Filterwheel: StarlightXpress 7x36mm EFW
Filters: Baader 7nm Ha, SII and OIII
Acquision Software: Main Sequence Software Sequence Generator Pro
Processing Software: Pixinsight 1.8.5

NGC2264 – Cone Nebula in SHO Narrowband

My latest image, I feel like I need more SII and OIII Data though to be perfectly honest, I captured quite a lot of dust even with narrowband mainly due to the high amount of HA frames I suspect, well here it is

Image Details:
27x 600S in 7nm HA
18x 600S in 7nm OIII
18x 600S in 7nm SII

25 Darks and Flats subtracted from lights

Data was acquired on the following dates: 18th, 19th, 20th and 21st January 2017, 13th and 18th February 2017

Equipment Used:
Imaging Scope: Sky-Watcher​ Quattro 8-CF Imaging Newtonian @F4 with the Skywatcher Aplanatic Coma Corrector
Imaging Camera: Atik Cameras​ 383L+ Mono CCD Cooled to -20C
Guide Scope: Celestron Telescopes​ C80ED Refractor
Guide Camera: Qhyccd​ QHY5L-II Mono
Mount: Sky-Watcher EQ8 Pro
Filter Wheel: Starlight Xpress Ltd​ 7x36mm EFW
Filters: Baader Planetarium​ 7nm HA, OIII and SII 36mm Unmounted
Image Acquisition: Main Sequence Software​ SGPro
Stacking and Combining: Maxim-DL
Processing: PixInsight​

Atik 383L+ Cooled Mono CCD Imaging Camera

After owning the Atik 383L+ Mono CCD Camera for over three years now, I would say I am definitely qualified to write a review.  I bought my camera back in 2013 when I lived in Ireland it was during the time when I transitioned from imaging with a Cooled and Modified DSLR Camera to Mono CCD Imaging.  At the time I was considering one of two cameras, the QHY8 Mono CCD and the Atik 383L+ Mono CCD, at the time the QHY was slightly cheaper but the Cooling Delta and Readout Noise was better on the Atik despite the fact that they both used the Kodak KAF8300 chip.

When I first received my camera, I was thoroughly impressed with the build quality, the red aluminium casing gave it a really professional feel to the camera and came complete with USB Cable, 12v Cigarette Power Cable and Software Media, all packaged really well, and when taking the camera out of the box, you could tell that Atik had put a lot of effort and consideration into their build quality and finish of the camera.  So far so good!

People quite often ask me how big the camera is, it just so happens that at the time I got my camera, I took a picture of the camera next to a AAA battery, just for comparison you can see that it is a fairly compact camera and at around 700g wasn’t too heavy either.

Because I couldn’t wait until my filterwheel had arrived, I wanted to test the camera functionality, so I installed all of the software onto my desktop PC and plugged the camera in.  At the time I got the camera, I was using Nebulosity to perform my image acquisition, so the first thing to do was build my dark frames at my desired temperature of -20C.  The dark frames showed very little in the way of noise which I was extremely happy with.  The installation of Drivers and  ASCOM Platform drivers all went perfectly without any problems, and Nebulosity worked well using the ASCOM Camera platform driver.

Once my filterwheel had arrived from StarlightXpress it was time to get the camera aquainted with the telescope, and at the time I was using an Astro-Tech 8 Inch Ritchey Chretien telescope on my already 3 Year Old NEQ6-Pro mount. Mating the camera to the filterwheel was relatively easy, I placed a thin cork shim onto the male thread of the filterwheel and screwed the camera on and adjusted the rotation of the filterwheel adapter to make sure the camera was at the right angle, I used the rubber shim to stop the metal to metal binding which makes it difficult to remove later, adding in the cork shim still allows it to be tightened up.

Since I had built my dark frame library, it was time to build my flat frames library, for this I used an EL Panel, one of the things I noticed was that a short exposure time of <1.0 seconds left a dark area to the lower right of the frame, after speaking with Atik they confirmed it was just the mechanical shutter, so I had to reduce the light on the EL Panel in order to increase the exposure time to get around this, other than that my flat frame library was built.

My first light for the camera was going to come from NGC7635 – Bubble Nebula in Narrowband, and whilst I must admit my imaging has come a long way since I took this picture, it is what it is and I was very happy with the results of sensitivity the camera delivered especially as this image is only 3x1800S frames for HA, OIII and SII.  Since I have had the camera, I have produced a substantial number of images to date and continue to do so using my Atik 383L+ Mono CCD Camera.

So how does Atik fair with me as a company, well it just so happens that I had to send my camera away for service due to excessive moisture causing Ice Crystals during cooling, I filed a support ticket with them and within a few days I got my camera back completely moisture free, I do not blame the camera here for the moisture, but more the fact that when I had my observatory located 15 miles away, I used to forget to switch the camera power off which would push a lot of moisture through the camera.  But the service from Atik was simply awesome.

Here’s a picture of the camera still used today attached to my F4 Quattro, I use Sequence Generator Pro for all my target acquisitions today but still using the ASCOM Camera Driver which is extremely stable

Just to recap why I am happy with the camera:

  • Build Quality
  • Size and Weight
  • Software Deployment
  • Sensitivity
  • Quietness of the camera

What could have been better?

  • Power cable – This could have been a stretchable power cable as I did run into a problem recently where the cable became snagged and it ripped the wire out of the jack plug that plugs into the camera, fortunately it didn’t damage the plug in port of the camera
  • Heated chip chamber, most cameras seem to have this now
  • Different colour options – I would have loved the camera in Blue or Green

You can see many of the images I have taken with this camera in my CCD Image Gallery Section here

 

 

NGC6960 – Witch’s Broom Nebula in Hubble Palette Narrowband

NGC6960 - Witches Broom
NGC6960 – Witches Broom

How Fitting for Halloween……My latest image – NGC6960 – Witch’s Broom in Hubble Palette Narrowband

Commonly referred to as the Witch’s Broom or the Western Veil of the larger Veil Nebula, this lies approximately 1470 Light years away.

In my opinion this is not an easy subject to image, and even more difficult to process, the image details are as follows:

15x600S in 7nm HA
15x600S in 7nm SII
15x600S in 7nm OIII
25 Darks
25 Flats

The HA was also used as a Luminance Layer

Equipment Used:
Imaging Scope: Sky-Watcher Quattro 8-CF 8″ F4 Newtonian
Guide Scope: Celestron Telescopes C80ED Refractor
Mount: Sky-Watcher EQ8 Pro
Imaging Camera: Atik Cameras 383L+ Mono CCD Cooled to -20C
Guide Camera: Qhyccd QHY5L-II
Image Acquisition: Main Sequence Software Sequence Generator Pro
Guide Software: PHD2

Processing:
Pre-Processing: Maxim-DL for STacking, Darks and Flats Subtracting and Alignment of Colour Planes
Post Processing: Photoshop CS5, Noise Ninja

NGC7380 – Wizard Nebula in Hubble Palette Narrowband

Image Details:
22x 600S – 7nm HA
19x 600S – 7nm OIII
19x 600S – 7nm SII
25 Darks and 25 Flat frames for each filter

Equipment Used:
Imaging Scope: Sky-Watcher Quattro 8-CF 8″ F4 Newtonian
Guide Scope: Celestron Telescopes C80ED
Imaging Camera: Atik Cameras 383L+ Mono CCD Cooled to -20C
Guide Camera: Qhyccd 5L-II
Mount: Sky-Watcher EQ8 Pro
Capture Software: Main Sequence Software Sequence Generator Pro
Guide Software: PHD2
Dark/Flat Subtraction and Stacking: Maxim-DL
Post Processing: PixInsight

IC1396 – Elephant’s Trunk Nebula in Hubble Palette Narrowband

IC1396 – Elephant’s Trunk Nebula in Hubble Palette Narrowband

Image consists of
15x 600S – 7nm HA
15x 600s – 7nm OIII
15x 600s – 7nm SII

HA Layer was also used as Luminance and Overlay layer

All data was obtained over five nights, 7th and 8th September 18th September, 22nd September and 23rd September 2016

Equipment Used:
Imaging Scope: Sky-Watcher Quattro 8-CF 8″ F4 Newtonian
Guide Scope: Celestron Telescopes C80ED
Imaging Camera: Atik Cameras 383L+ Mono CCD Cooled to -20C
Guide Camera: Qhyccd 5L-II
Mount: Sky-Watcher EQ8 Pro
Capture Software: Main Sequence Software Sequence Generator Pro
Guide Software: PHD2
Dark/Flat Subtraction and Stacking: Maxim-DL
Post Processing: Photoshop

To date I think this is my best image so far, I am very happy with the results of the image and the colour balance obtained