Light Vortex Astronomy
  • Blog
  • Astrophotographs
  • Articles
  • Tutorials
  • Links
  • About Me
  • About e-EyE
 ​Send a Gift via PayPal:

Remote Hosting in Spain:
Picture

 

FeatherTouch 3" Focuser Installed and Andromeda Galaxy Image Finished

1/9/2016

2 Comments

 
​With the long weekend in Gibraltar gone, so is my trip to e-EyE concluded. I primarily went there to help the owner learn PixInsight in person, which he very much enjoyed. Part of my trip was also spent making sure my equipment was fine. This included installing the recently-purchased FeatherTouch 3" focuser upgrade for my Takahashi FSQ-85ED as well as setting up the replacement Aviosys IP Power 9258 (after the first one I had died on me). The following are some photographs of my equipment setup:
Picture
Picture
Picture
​Aside from installing the new telescope focuser and IP Power, I also moved the Mini PC to a much bigger tupperware box, which is no longer screwed on to the side of the mount and is instead placed behind the mount on the pier plate. I cut a circular aperture into the box lid and drilled four small holes along the corners. This allowed me to mount a 120 mm USB-powered computer fan, which blows air into the box directly on to the Mini PC. The sides of the box are slit to allow cables through and for extra ventilation. I lined the bottom of the box with anti-vibration padding in order to prevent any vibrations from the fan being transmitted to the equipment. I first tested this setup with the box screwed on to the side of the mount but unfortunately the vibrations from the fan were producing very noticeable star elongation in all exposures. 

The FeatherTouch focuser upgrade to the telescope is certainly working wonders. No longer do I have the unpleasantness of looking at very odd autofocus graphs, unable to find the focal point. Now I actually get perfect to nearly-perfect V-curves, as with the following two examples:
Picture
Picture
​The above is carried out by Sequence Generator Pro, with 2x2 binning and 30 second exposures on Hydrogen-Alpha. For LRGB, I set 5 second​ exposures and the V-curves are just as good. The focal point is very close to the beginning of the focuser travel, since the focuser travel is of 7,285 steps, but it is working well so there is no need to alter the optical train. If needed, I could always shorten it slightly in order to push the camera further out via the focuser travel. One thing to note is that I had to enable Sequence Generator Pro's Focuser Backlash Compensation feature, setting it to 50 steps IN. This is because the binding of the autofocuser motor to the focuser axle is not perfect and when it changes focus direction, there is a little bit of backlash at 50 motor steps. Since Sequence Generator Pro autofocuses by moving the camera in to produce a V-curve and then set the best focal point by moving the camera out, I set the backlash compensation to 50 steps IN. According to Sequence Generator Pro, this is applied when the focuser moves out after having moved in. With this enabled, I get perfect focus every single time. 

Finally, I completed work on my recent image of M31 Andromeda Galaxy, along with the M32 and M110​ galaxies next to it. The image comprises a massive 76 hours of total exposure time - an abnormally large amount of imaging time for one target for me. This included a total of 760 exposures. In LRGB, I captured 1 minute and 10 minute exposures (for HDR on the core). This was done for all four panels of the mosaic, with 30 exposures in Luminance and 20 exposures per colour channel. Then to enhance the image further, I captured 10 exposures each of 15 minutes in Hydrogen-Alpha, for all four panels of the mosaic as well. The end result is shown below. If you click the image, it will take you to the high-resolution version on Flickr​. 
Picture
​Overall an extremely pleasing result for me. It has been quite popular on Facebook since I posted it on the Light Vortex Astronomy page and shared it to several astronomy/astrophotography groups. Some commented they felt there was a little too much magenta. I guess they refer to the intensity of the star formation regions enhanced by combining Hydrogen-Alpha with the Red colour channel. I personally love this as I can see pretty much everything there is to see along all the galaxy's spiral arms and even blobs extending beyond into the far reaches of the galaxy. All a matter of personal taste, I guess - I love seeing galaxy images like this!
2 Comments
Peter Nerbun link
20/9/2016 19:43:09

Hi Kayron, I purchased a Starlight Instruments FeatherTouch focuser and an electronic focusing control system that includes a motorized focuser for my SCT; I've been using SGPro's auto focus program to move the focuser in and out until the focus point at the base of the V graph is recognized. I've been using 1x1 binning for my auto focus frames because we discussed how the ICX694 sensor is better adapted for 1x1 binning rather than it is for 2x2 when deep sky imaging. I was wondering why you use 2x2 binning when running SGP's auto focus program and do you think that 2x2 binning of my camera's ICX694 sensor makes more sense when generating SGPro's auto focus frames?

Thanks,
Peter

Reply
Kayron Mercieca link
27/11/2016 17:39:55

Hi Peter,

Indeed I do use 2x2 binning for my autofocusing in SGP. The reason I do this is two-fold:

1. The autofocus frames (and any frame actually) downloads much, much quicker from the camera with 2x2 binning, making autofocus much faster than in 1x1.

2. With 2x2 binning, the autofocus frames pick up a lot more stars in less exposure time. This not only makes autofocusing faster, but it also makes it more reliable, especially with my narrowband 3nm filters.

I've noticed there's no problem whatsoever with focus if you focus with 2x2 binning but image at 1x1. The two benefits above make it worth-while doing, in my opinion! :)

Best Regards,
Kayron

Reply



Leave a Reply.

    Archives

    July 2019
    January 2019
    December 2018
    October 2018
    September 2018
    August 2018
    April 2018
    March 2018
    January 2018
    November 2017
    October 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    June 2015
    May 2015
    January 2015
    October 2014
    September 2014
    August 2014
    July 2014