Revisiting M20

[g__day (Matthew)]

As a workout for my cooled (ice box) camera Canon 40D - I decided to go long on the Triffid. This is a combine of 50 shots totaling just shy of 20 hours of data taken thru a C9.25 at F10.

Happy with the pointing, tracking and improved dark performance of the cooled camera - as most of the shots are 30 minute subs.

[MGTechDVP (Mariusz)]

Excellent work.

I also use a modded Canon 40D for my astrophotography.

What ISO setting did you do these subs at?... I imagine it would be ISO100 since when I did my subs at ISO400 and 10 minutes overexposed the skyglow to a milky brown.

Mariusz

[Placidus (Mike and Trish)]

Very good going indeed with those half-hour subs. Stars small and round and sharp.

If you clip the blacks a tad less, you'll get more subtle edges to the reflection nebulosity. Might be worth a go.

Best,
Mike

[g__day (Matthew)]

I use ISO 400, its the cooling that makes all the difference.

Totally agree on the clipping comment - was playing around here a bit with photoshop and went too far. What I would really like to try is use the sub 600 second shots to get the stars and the 1200 and 1800 second shots for the nebulae and combine the two so that the stars aren't blown out, especially in the core!

[RickS (Rick)]

30 minute DSLR subs are impressive! Nice work, Matthew.

[RobC (Rob)]

Nice image , well done

Curious to know if are you using an Edge HD 9.25.

I am running similar tests using an EDGE HD 11 on M20 with an uncooled 60D at 400 ISO. 10 Minutes is about the maximum I can expose. Could you post one of your 30 minute subs

Thanks

Rob

[g__day (Matthew)]

Not the edge - a carbon fibre 9.25 - so it holds focus rather well.

A typical 30 minute sub - no processing at all (so you can see how dirty the filter is in spots).

If I set the cooling lower I wonder if I could go up to an hour subs ?

[johnnyt123 (John)]

Good image there..

But i feel you may have over clipped the black...
but great tracking for 30min subs..!!

well done

Regards..

John

[RobC (Rob)]

Originally Posted by g__day

Not the edge - a carbon fibre 9.25 - so it holds focus rather well.

A typical 30 minute sub - no processing at all (so you can see how dirty the filter is in spots).

If I set the cooling lower I wonder if I could go up to an hour subs ?

Thanks Matt.

The 30 minute sub is interesting. Suggest you experiment and drop the ISO to 200, run some more subs and compare the differences. I believe 200 ISO represents unity gain for your camera.

I am newbie at this and I am struggling trying to get a handle, on the optimum Canon 60D ISO and exposure time settings for different temperatures and seeing conditions.

We should make it easier for ourselves and just buy a cooled CCD camera. As you have the art of guiding mastered all you have to do is set an exposure time.

Cheers and keep us posted on what you discover.

Rob

[g__day (Matthew)]

Tonight I am playing with 1800 sec, 2400 sec right up to 3600 second subs - and the results look pretty good so far. I selected ISO 400 after reading an article Craig Stark wrote on how the Canon processes its raw files, seems like it does some sorts of non linear adjustment to address dark current that isn't simple. ISO 400 works well for me so far.

So having now about 24 hours of light frames on M20 its time to tweak the processing and move onto something new!

[Rex]

30min subs!!!!!! Great work Matthew, and some nice detail in there. I agree with the black clipped comment but overall a great image. Your tracking and guiding is extraordinarily good. Well done mate.

[edwards33 (Roger)]

Nice image , well done


Roger

[rustigsmed (Russell)]

hi matthew,

nice job - in particular the polar alignment -looks good.

a good workout indeed, nice to see the coolerbox perform so well.

when I go past about 3-4 minutes on my dslr I struggle to process out the whitewash/opaqueness that results - unless I've thrown a narrowband filter in front of it. I think going for shorter sub lengths will make it easier for you to process when doing broadband.

but lovely result nonetheless you know you can push it if you need to!

Cheers

Russ