Problem with Flats

Give PixInsight a try for processing. I have never used flats (perhaps I should - I really haven't a clue but I believe the DBE tool in PI does it all). Here is a combination of Ha & S II without any flats. (Using Astronomik 12nm filters). This might not be the right combination for this subject.....but I don't mind that.

www.flickr.com/photos/kinch-astro/12128336086/in/photostream/

Kinch.

I have my flats sorted, yes I still need flats with NB filters as the frame goes darker towards the corners.

Nice Picture there Kinch

I'd be wary of relying on software to give me what it thinks is the "optimum" ADU. CCD characterisation is not too hard and you will determine definitively the characteristics of your own CCD. It has certainly been reported that CCD characterisation has led to generated that doesn't come within a barge-pole length of the manufacturer's claims...

Characterisation will help you get an extra few percentage points in the quality of you're images. For science, its a must do.

What's an NB filter?

Kinch - I doubt very much that PixInsight has the ability to anything with optical artifacts other than to perhaps mask them in some arbitrary way. I'm not aware on anyone in the astro software community offering a software-only-flat-removal module. The only way to accurately remove optical artifacts from images is to use flats. And the only way to accurately create flats is to start with characterising your CCD.

However, and it certainly shows (or rather doesn't) in your excellent Crab Nebula image, that for some systems, flats are really not that important for day-to-day images. But if you're a wannabee Gendler, Croman, Peach etc. roll your sleeves up and get used to doing the hard work. I once heard it said that the planet imagers would collimate their telescope every 30 minutes to squeeze every last accurate pixel out of their systems. And it showed.

FWIW

Dave

Hi Dave - I bow to your superior knowledge on the subject . Please note one very important comment I made in that last post....."I really haven't a clue". I guess that I have been lucky with my gear but for sure to achieve the quality I want to achieve (at this time anyway) I do not need to do flats or darks or anything other than take as many subs as I can on any particular night and have some fun processing that data afterwards. Perhaps when I get 'over the hump' and decide to get serious I will "roll my sleeves up".
A year ago I put my first picture up to the public. I felt great about it at the time but I cringe now when I look at what I was doing a year ago. I have little doubt that a year from now I will have similar feelings re what I am making public at the moment - but that is OK and I appreciate any and all constructive comments. Bit by bit we improve..............but I am not ready for the hard work - just yet I am having too much fun just experimenting.
Very best regards....and thanks for your comments.
Kinch.

Whoops! Sorry Kinch - didn't mean that to come across as critical of you :blush:

I doubt very much you've been lucky... To get an image of the Crab as good as yours takes a good bit of work as you know. I'm not sure of your setup - there are definitely some that really don't require much (if any) calibration. Your is clearly one of those setups and you're getting great results.

But... when (I doubt the use of the word 'if') you get serious, not only will sleeves be rolled up but so will trouser legs and everything else as you hurtle headlong into the weird and wonderful world of darks, flats, bias, flat-darks, T-Shirt flats, ADU, RBI, CCD Offset, dark current etc... Of course, your bank balance is now connected in an inverse manner to your [strike]enthusiasm[/strike] obsession.

By the way, deja vu - my very first image was appalling. But I actually love it. It was mine, I did it and it reminds me of how far I've come with the ever helpful folks here on IFAS. Keep on with the experimenting and keep sharing your images here. Whether you want to be a Rob Gendler or a Damien Peach or Carl O'Beirnes, these boards are definitely the place for you...

Dave

Hi again Dave,
I may not have said it right - but I did not view your comments as critical. I am here for constructive comments and that is how I viewed you post. When I started out I was going that road with "T-shirts at twilight" but I have since changed my gear and find that I have made my "road to perfection" that little bit easier. (I know I will never get there though but the journey rather than the destination is where I get my 'kicks')
You can see my gear and some other shots here www.flickr.com/photos/kinch-astro/ and going by your own experience you will understand when I say that these shots may not great but they are mine :-)
Kinch.