Some objects worked well, others not so good but I have ideas to try next time I am outside.
All the images were captured using these settings:
- 100 x 15s
- gain=20
- brightness=10
- 1280 x 960
- RAW16
- output to FITS format
Debayer pattern used was BGGR - obtained from the 'Image Headers' tab in FITS Liberator.
The following attached items apply to all the images below:
- Camera settings file
- Sharpcap capture screen showing histogram
- FITS capture file histogram shown in FITS Liberator
- Celestron C8 SCT with CG5 Advanced GT equatorial mount
- TS 0.5x focal reducer
- no filters
- ZWO ASI120MC USB2 camera
- Toshiba C50 Satellite Pro, i3, 4Gb memory, 500Gb drive, Win 10 64-bit, £140 off eBay
M42 with M43
This image was OK, plenty of nebulosity and the 4 stars of the Trapezium visible. I also converted this image to mono within Photoshop.
M82 Cigar Galaxy
I think this is my best M82 to date, plenty going on in the galaxy core. I think I might need to re-focus more often during the longer imaging sessions.
M81 Bode's Galaxy
This was the first time I have managed to capture any of the fainter nebulosity for this object. My first process run in Photoshop gave just the bright centre but subsequent attempts using repeated small application of 'Curves' managed to bring out the faintness. I will retry this object with longer exposures/increased gain (as separate changes) as the histogram was not as 'full' and 'stretched' as the M42 histogram.
M52 Open Cluster in Cassiopiea
A reasonable image, next time I will try increased exposure/gain to see if I can capture more stars.
M78 in Orion
This image is fainter and so is going to need longer exposures and/or increased gain. More experimentation needed here.
M76 Little Dumbbell Nebula
This image is fainter and so is going to need longer exposures and/or increased gain. More experimentation needed here.
M1 Crab Nebula This image is fainter and so is going to need longer exposures and/or increased gain. More experimentation needed here.
For this object, I used the display histogram stretch to check that I had the faint nebula in my display.
In summary, by analysing the results of previous imaging sessions, I feel that things are moving (slowly) in the right direction for me.
The previous forum post I made using the ASI120MC for DSO's had me using gain=80. By reducing the gain to 20, I have, for the brighter objects, managed to obtain improved images which were less noisy and hence needed less post processing.
Please ask if there is anything I have missed out or not made clear in the write-up.
Dave