My latest attempt at M42

Dave, Rather than in software, I wonder if you would be better served with a bahtinov mask. Much better than a hartmann from what I read. Have a read here. www.focus-mask.com/

Calibos wrote:

Dave, Rather than in software, I wonder if you would be better served with a bahtinov mask. Much better than a hartmann from what I read. Have a read here. www.focus-mask.com/

You know, I read about this a while back and on initially reading calibos's post I was poo-poohing this a bit in my head. Call it software snobbery if you like:) But the more I read about the bahintov mask, the more I like the idea. Ok its clearly not going to be one for auto focusing but it is clearly repeatable unlike the hartmann mask. OTOH, once you got the hang of using the FWHM or 1/2 FD methods in software, you can also get repeatable results quickly and easily without having to attach a mask. The other advantage of the software methods is you can focus right at the target and not worry about mirror flop by focusing away from the target (on a bright star) and then slewing back to your quarry.

I might try and make one of these up tomorrow and give it a spin just for the crack.

Now I'm getting bad ideas in my head. I'm wondering if it would be possible to make a type of bahintov mask which fits in a 2" filter frame and then write a Maxim DL plugin to analyse when all the diffraction spikes are lined up. Hmm auto focus with a bahintov mask. Interesting. Experiments will no doubt follow.

I just wonder would it still work at the filter position rather than as a full aperture mask.

I think we were on the same wavelength David, I decided to image M42 as well (my second attempt at this object). M42 an old favourite of mind, I never get bored of looking at this wonderful object. I decided to image M42 with a DFK video camera and view the results, I was mildly surprised, could do with tweaking the focus and collimation a bit but the result is reasonable I think.
Colour and false colour enhancement of M42, the great Orion Nebula, 50 bitmap light frames (20 dark frames subtracted), size 1280 x 960 processed in Mira Pro. Images taken on December 28th / 29th. Equipment used: Celestron C8 + CG5-GT Mount. Images taken with DFK 41F02.AS Firewire video camera set at 16 second exposure in colour sequence mode.

www.flickr.com/photos/mike_foylan/3150494108/sizes/o/
www.flickr.com/photos/mike_foylan/3150494950/sizes/o/

Regards and clear skies
Mike

Hi Mike

Not a bad image at all. You can see the difference between the 30 second and the 16 second exposure.

DB

Nice one DeeBee.

Lets have a go at these bahtinov masks. I think I could use one also. I'll get the details and find some material we can use and we'll spend a cloudy night hammering something together. Your image really only lacks a sharp focus and a shorter exposure on M42 (or a mix of long and shorts might be better). Main point is the mask - Having read all the Cloudy nights thread it sounds the business:) Talk to you soon and Happy new year to you and 'erindoors.

- John Murphy