M42 HA Celestron RASA Atik 11000

[pyrasanth]

I continue to test the Celestron RASA with the Atik 11000. The image below was taken with a Baader 2" fast HA filter & consists of 26 120 sec subs under a  very bright moon. M42 is still very low at 30 degrees but the result is quite pleasing. Processing was done in PixInsight & PS 6.

I still don't have any flats for the repaired Atik so I'm using an old HA flat then the PixInsight background extraction tool to clean up the calibration.

Let me know what you think of the image. I still have a lot more HA data to bring in when I've finished the session tonight. As always blow the image up big- It's about a 50% crop of the full frame.

[symesie04]

Very nice, nice gentle whisps but your need some shorter subs for the core.

[Scott]

Afraid it doesn't work for me. You're starting to get some wispy stuff away from m42 and the running man but the targets are way over cooked. It always makes me wonder that so many people think M42 is one of the easy targets for imagers along with m31. they both have massive dynamic ranges making processing much more challenging. Just my opinion but you did ask . 

[pyrasanth]

Afraid it doesn't work for me. You're starting to get some wispy stuff away from m42 and the running man but the targets are way over cooked. It always makes me wonder that so many people think M42 is one of the easy targets for imagers along with m31. they both have massive dynamic ranges making processing much more challenging. Just my opinion but you did ask . 

I don't think M42 is an easy challenge at all. Only by doing can we aspire to do things better & I'm really receptive to critical comment. The target is bright & the RASA so fast that this object could become the challenge of the session. What I intend to do is to take the observations on board & shoot in 2 stages- the core with exposures of perhaps less than 5 seconds & the outer details at perhaps sub 20 seconds. I will need to do some test frames when M42 is higher to work out the best approach. It is low at present so suffers a bit from bloated stars.

But as always thanks for the observation.

[callisto]

Afraid it doesn't work for me. You're starting to get some wispy stuff away from m42 and the running man but the targets are way over cooked. It always makes me wonder that so many people think M42 is one of the easy targets for imagers along with m31. they both have massive dynamic ranges making processing much more challenging. Just my opinion but you did ask . 

Bad day Scott?............sorry, I'm such a spoon stirrer   

[Scott]

Bad day Scott?............sorry, I'm such a spoon stirrer   

Not at all.. when someone asks for an opinion, I think its my duty to be honest. I don't think that anything I said could be construde as offencive and if offence was taken  then I apoligise as this was never my intention.

Better to be honest than post the standard "nice image" comment

[callisto]

Not at all.. when someone asks for an opinion, I think its my duty to be honest. I don't think that anything I said could be construde as offencive and if offence was taken  then I apoligise as this was never my intention.

Better to be honest than post the standard "nice image" comment

I know, I know, just pulling ya leg buddy 

[theo]

That's showing a lot of potential. Plenty of the wispy stuff, I'm sure with the combined subs layered and blended to cover the wide dynamic range of M42 you could produce a first class image of this target with this equipment.

Pete

[laudropb]

I think it is a nice image which shows a lot of potential. Thanks for posting.

[Uranium235]

Afraid it doesn't work for me. You're starting to get some wispy stuff away from m42 and the running man but the targets are way over cooked. It always makes me wonder that so many people think M42 is one of the easy targets for imagers along with m31. they both have massive dynamic ranges making processing much more challenging. Just my opinion but you did ask . 

I think youve got it right in regard to the dynamic range of M42. Easy to capture, but hard to process it correctly.... its far too easy to burn the core on this so usually I end up using four or five layer masks to build it up. It especially gets tricky when youre chasing the stuff outside of M42.

He might be able to get away with using some of the raw, unstretched data to layer some of the core back in. But if the raw is burnt, its going to be a re-visit for some short subs (30s subs should do it). It might also need a vertical banding filter (noels actions will do that).

[ChrisLX200]

Getting (and maintaining) critical focus with one of these RASAs is not something I would undertake lightly myself, what method do you use to achieve focus?

ChrisH

[pyrasanth]

Getting (and maintaining) critical focus with one of these RASAs is not something I would undertake lightly myself, what method do you use to achieve focus?

ChrisH

Focus as you said is really critical. I allow the RASA to reach ambient temperature for a good couple of hours before an imaging session. The instrument has a feathertouch focuser as standard. I removed the manual head & fitted this with the ascom motor driven assembly for the feathertouch. I then use focusmax to achieve critical focus and then try & refocus every hour or between filter changes. I'm quite pleased however that once focused it stays pretty stable for a few hours at least.

[pyrasanth]

Not at all.. when someone asks for an opinion, I think its my duty to be honest. I don't think that anything I said could be construde as offencive and if offence was taken  then I apoligise as this was never my intention.

Better to be honest than post the standard "nice image" comment

No offence taken at all. It's all positive advice from my perspective. However it would be good if you guys can give me a suggested workflow to capture M42. Decisions need to be taken whether I go LRGB or narrow-band. I have the filters, camera & telescope but what I don't have currently is a plan of the required exposure workflow. The RASA at F2.2 is so fast that any lengthy exposure will burn out the core & remember lengthy for the RASA is often a minute or less so I envisage M42's core to be over exposed in less than 5 seconds!

It does not help that the Atik 11000 has 9 um pixel size which are sensitive light catching buckets but the well depth is deep so I guess wide field has its compromises for sure.

Let me know your thoughts on an exposure workflow to capture the full dynamic range & I will work with you all to make the best of what I can achieve.

[Zakalwe]

M42 is one of the few targets that needs HDR treatment- lots of stacks of different exposure lengths which are then blended to get the full dynamic range. Cameras just do not have the dynamic range to capture the faint wispy stuff and the core in one go. It's definitely not a beginners target,  IMHO. Even with my "slow" f5.3 system I used a stack of 60 second subs in the very heart of the core (in H-a too!).

[ollypenrice]

I think you need flats fairly urgently. I'm not convinced by the outlying nebulosity as it stands. There are two dark 'shafts' which should be emerging in Ha either side of the Great Nebula and I see just a hint of one of them which then gets brightened out towards the edge of field. I also agree that this is one which needs multiple sub lengths. This is a superb tutorial, too. http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM  Ithink it's the best way to handle M42.  It's one of the hardest targets to process in my view.

However, what we all need is lots of signal - and you have it!

Olly

[Scott]

I can't help you with exposure times but this method may suit you. whether it can be adapted to pixinsight I have no idea

http://morrisastronomy.blogspot.co.uk/2013/12/step-by-step-processing-of-orion-nebula.html