M45 - first draft

[xanthic]

Here is M45 I grabbed last night. 45 mins worth of 5 min subs, ISO 800,

 

I've posted this in Discussion, mostly because I think I need a bit of advice. The first mistake I made was not rotating the camera 90 degrees to get the subject in properly. I also seem to get a fair bit of vignetting on my images. Is that a consequence of my gear and is there anything I can do to reduce it?

 

Edit - removed the pic with the awful white balance (not sure what happened there...)

 

Edited November 5, 2013 by xanthic

[Perkil8r]

To reduce vignetting you need to do Flats really. You can try post processing techniques but these will degrade the actual data where as proper flats will not. That should really be a starting point as the finished stack will then be quite different to what you have here so will require different processing to this set.

 

Don't worry too much, you can still do flats for this now, but any dust bunnies will not be removed. It can cause problems doing it after the event so to speak and won't be "ideal" but I think it will still help you in this case

[xanthic]

Any prefered method for doing flats with a DSLR? I've read of a few on SGL. Not got round to trying any yet.

[Perkil8r]

I presume it was done on the 150p?

 

Pop camera back onto the scope, take dust cap off and cover the end with a sheet of plain white paper. Point at a fairly even illuminated area (will need to be bright for this method) and take a few shots at any ISO and short exposures until you get the historgram in the middle ish. Delete all the test ones and fire off 21 (that's how many I do) and use these as your flats.

 

Normally you would do them with the camera set up exactly as it was when you took your images so as to remove dust etc from the stack, but as you have no doubt already taken the camera off the scope you will need to guess roughly where it was. Also you need to make sure the focus is somewhere near where it was.

[xanthic]

Thanks Mike. Yes, too late for this image but I'll be better prepared for the next time around. All part of the learning process

[Perkil8r]

Thanks Mike. Yes, too late for this image but I'll be better prepared for the next time around. All part of the learning process

 

Not too late Just do a rough approximation, it will be good enough to help with the vignetting, trust me

[xanthic]

I made some flats using the paper method you described above and a torch I have with a smoothed beam (it has an orange peel reflector so produces a very even spot). It's certainly made a difference. Thanks for the help

 

Update - I've just given another one of my images a once over with the flats and they make a massive difference to the contrast. Very impressed. Will ensure I get flats for next session.

 

Edited November 6, 2013 by xanthic

[dawson]

Looks loads better!

Jd

[Perkil8r]

Nice one, glad it worked for you Certainly looks a lot better IMO

[xanthic]

Yes, I am more pleased with that one, though really needs more and longer subs and probably lower ISO (I start to get a fair bit of noise around 800).

 

One further question - should I do the flats with the CLS filter in?

[Perkil8r]

yes.