Getting the best FWHM in your images is something that I have struggled with when imaging a whole night. As the temperature fluctuates, so does the FWHM in your images, this was a problem I had with my images at the beginning of the season. I looked around and the only focuser I could find was not a stepper motor focuser, so it didn’t offer predictable results. Since I am using the stock focuser for my Sky-Watcher Quattro 8-CF (and it’s a solid focuser at that), I did not really want to change focuser mid-season, so I did some research and landed upon the PrimaluceLabs Sesto Senso ROBO Focuser.
Now my expectations here were pretty low since I tried an electronic focuser and tried to use some sort of Auto Focus routine without any length of success, but when the Sesto Senso arrived I was excited as I looked at it and thought to myself that this would do the job.
Out of the box the Sesto Senso is very solid, good quality feel to it, and came with a bunch of different adapters for different focusers, one specifically for my Sky-Watcher Focuser too. I read the installation instructions a couple of times and set to work on upgrading my scope.
Installation Installation was fairly easy and straight forward, I removed the slow focusing knob off the focuser and attached the adapter for the Sky-Watcher that came with the Sesto Senso, so within 30 minutes it was successfully fitted. And I can still manually focus with the fast focusing knob on the other side of the focuser:
After all the physical installation was done, I then needed to install the software on the observatory PC, since I image using Sequence Generator Pro, I proceeded to install Sesto Software and the ASCOM driver so that SGPro could talk to the focuser, again this was relatively simple to do. Once this was completed it was important to load up the Sesto software and perform a calibration so that the Sesto Senso knows where the most innner and outer focus positions are.
Setting the Focus Control module in SGPro was a breeze, for this I used a Focusing Mask to get a rough focus and set that point for all of my filters, now the following setting are what works for me really well, but basically:
I use 20 data points to achieve focus.
Step size between focus points is 20
Focus frame is 10 seconds for all filters, this is to get a better normalised focus frame, I was finding 5 seconds was too short and gave un-predictable results.
I set it to re-focus after a temperature change of 3.0 Degrees C since the last focus.
I re-focus on any centering action which is useful if you use a mirrored telescope like me.
I have now been using the Sesto Senso for a few months now and it has not failed me, I maintain a good FWHM value throughout the night and it an awesome piece of kit, well done Primaluce Labs. Is there anything that I would change about it?
Only one thing…….It requires separate power, which in all honesty I can understand why but if I could run the power through USB that would be a bonus.
One problem I have with the Auto Focus routine in SGPro is that in the image sequence, since my filters for LRGB are all parfocal, but my Narrowband filters are not, I only wish to focus on a filter change if it’s going from LRGB to Narrowband to LRGB or Narrowband to Narrowband, unfortunately SGPro doesn’t have that intelligence in the sequence, I am trying to persuade Jared to have that in there to make life that bit more simple.
Anyway I hope this review inspires you to consider this awesome piece of kit, it’s certainly helped me!
This is my first time ever imaging this target, and like the Crescent Nebula and Pelican Nebula I am limited to a 2.5 hour window per night to acquire data due to trees / house getting in the way, luckily I managed to get a lot of Ha data on this subject to blend this into the RGB image which smoothed out the lack of data for RGB somewhat, I would have liked to have got more RGB Data and I may re-image this with longer exposures on RGB next time also
Image Details: 56x150S in R 56x150S in G 66x150S in B 101x300S in Ha
All frames had 101 Darks and Flats applied, the Ha layer was blended using the new NBRGB Script in PixInsight 1.8.6, the more zoomed in picture is of the same data but with a 2x drizzle applied then cropped
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 RGB and Ha 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
I spent a lot of time looking at PowerBoxes/USB Controllers, the late Per Frejvall had developed a very nice Remote USB Hub but of course with the passing of Per, these are no longer available. I looked at two hubs, the HitechAstro Mount Hub Pro abnd the one I settled for was the Pegasus Astro Ultimate PowerBox.
Unboxing the PowerBox I was pleased with the build quality, they even ship mounting brackets for you to be able to mount it onto your setup, here’s an image of mine mounted on top of my Sky-Watcher Quattro:
I loaded up the software onto the observatory PC and again pleasantly surprised at how easy it was to get started and configure the names of the powered devices connected as well as names for each of the dew heaters, in the following image you can see my power connected devices and my dew heater for my guider camera:
I configured the software to automatically power my devices the moment the unit is switched on, so what do I have connected to the PowerBox?
QHY5L-II Guide Camera
StarlightXpress USB Filterwheel
PrimaluceLabs ROBO Focuser
EQ8 Pro Mount PC-Direct Cable
I didn’t connect my QHY183M at the moment as I discovered that during image download it seemed to cause a timeout on the QHY5L-II Camera, I have raised a ticket with Pegasus Astro on this one. From a Power perspective, I only have my QHY183M and my Rear Fan assembly/heater connected as I currently do not have the power cable to connect directly to the hub for the EQ8 Pro (On Order). There is also a temperature sensor for the ultimate version, which works well as an interface for Sequence Generator Pro and my Auto Focuser routines.
I have been using the Hub now for a good few months, I am pretty happy with it, am I totally happy you might ask, well to be honest there’s a couple of niggly things that I have emailed Pegasus Astro about (awaiting a response):
Voltage. I am running 13.8V regulated bench power supply capable of delivering up to 15A which is powering the hub, however when devices such as the camera, dew heater, fan assembly are all running, the voltage level drops down to around 12V according to the software, I would not expect this to do so, I would expect it to remain 13.8V. My EQ8 Pro mount is powered by the same supply (but not through the hub currently) and during slew the voltage in the software does not change, so it’s obviously something being caluclated within the hub somewhere.
Issue with USB3 Camera (QHY183M) is still outstanding
When you set the power to the dew heater for example I always run it at 170, however when the software restarts you have to manually go and set this again
Ability to reboot or “Disconnect” a specific USB Port remotely would have been nice.
The main reason I wanted something like this was the ability to reboot the hub remotely, with standard USB Hubs this is not possible, as above, I would love to have a bit more granularity on this and have it on a per USB port but it works well for me right now.