Experiences with hyperstar imaging- my first 4 months (sorry for the monster post!)

[Ikonnikov]

As promised in my introductory post, here are some images from my (fairly) new hyperstar setup and also a bit about my progress so far.

After starting with a mono mammut camera on a Nexstar 5SE and playing for a few months I upgraded to an HEQ5 mount and then after more reading around I took the plunge with a C8 plus hyperstar lens and an Atik 428EX OSC in October. I also bought Pixinsight after using the trial version and watching Harry Page’s videos. I wanted to start auto guiding at the same time and set up a 60mm finder / QHY5v for use with PhD. My first hyperstar images were better than anything with the mammut but weren’t great and after some playing around and more reading there were several things I wanted to try to improve.

Focusing was a bit hit and miss. I have a micro focusser on the C8 so I could make fine adjustments but wasn’t confident of hitting focus. I tried a Bahtinov mask on my dew shield but this didn’t really work (maybe as it was too far from the corrector plate?). I settled on the fine focus tool in Nebulosity which works quite well although requires some patience manually. Using Nebulosity with PhD also allowed me to start dithering which has helped to bring down noise in my images.

Another issue was generation of (messy) diffraction spikes by camera cables. It seems many tie off cables at right-angles to make neat orthogonal spikes but others have curved them to prevent any spikes forming. I had a go at this by making a D-shaped foam piece to tape the cables to (which I’d seen used on a C11 setup somewhere on the web) and this seems to work reasonably well.

Finally, after ignoring flat-field calibration until very recently (relying solely on Pixinsight’s DBE tool) I bought a luminescent panel and made some flats. Although DBE is pretty good the flats have helped me to stretch my images more and deal better with nebulosity. 

In summary I’m fairly happy with how things are going so far but obviously I still have loads to learn to get the best out of my gear/images (especially with processing). I’m very grateful for the wealth of advice present in the SGL forums (I would have been lost without it!). I do have some questions though...

• I’d like my images to be a little sharper if pos but am not sure if this is a limitation of seeing, guiding, poor focusing, processing, sensor resolution or something else; if anybody has any thoughts I’d be grateful to hear them.

• What are people's opinions on the use of sharpening functions like unsharp mask and deconvolution?

• Although a bit extravagant, would luminance images from a mono camera increase the effective resolution/ image sharpness much when combined with the OSC data? I’m currently at 2.2 arcseconds /pixel with the 428EX OSC. If I did decide to go down this road I would want to get another Atik 4-series so I could easily interchange the cameras on the HS. However would it be better to go for smaller pixels for higher resolution (eg atik 450L) or would the reduced well-depth/dynamic range give substantially inferior images to a mono 428EX? The latter would obviously be more convenient for processing as it would give the same image size/scale as my current OSC.

Cheers,

Paul

Cone nebula (10 x 6min subs with LPS V4 nebula filter, dark calibration, processing in Pixinsight)

Horsehead and Flame nebulae (11 x 6min subs with LPS V4 nebula filter, dark and flat-field calibration, processing in Pixinsight)

M33 (23 x 5min subs with LPS P2 filter, dark and flat-field calibrated, processing in Pixinsight)

M81 and M82 (4 x 5min subs with LPS P2 filter, dark and flat-field calibrated, processing in Pixinsight)

[sologuitarist61]

Fantastic images (especially like the Horase Head!). Good detail and well controlled use of colour as well - first class!

[Eddy_]

lovely flame/horsehead shots, very nice - thanks

[Ikonnikov]

Thank you for the encouragement! Here's the Horsehead with a bit less compression.hh proc 14_2_14 no hdr 2.tif

[Robbo AR]

Beautiful photos.

[mhard26339]

Hi Paul,

I have been trying (on and off) for about a year now but do not have any images anywhere near as good as yours. Occasionally it has been one step forwrad and 2 back but the support and encouragement from these pages is great. Will post when I have something decent???

Regards

Mike