Re: [APML] Saving ngc3242 from the scrap pile...

["John Boudreau" <jeboud@attbi.com>]

----- Original Message -----
From: "Jeff Ball" <jeffball@zoominternet.net>

> Hello John,
> Thanks for the great post.  I enjoyed walking through your processing
> steps.  I really appreciate your technique on aligning RGB and have now
> made it a part of my processing.  I have no experience with
> deconvoluting.  Another learning curve to be scaled.  I see this
> referenced mostly with CCD images.  What are the applications to film
> imaging?  Mostly pertinent to high resolution images?  Thanks for any
> help on this.

Thanks Jeff. I was sitting on the NGC3242 image for some time, every now and
then trying different things to "rescue" it. The weather hasn't allowed me
to reshoot it this year.

As far as the deconvolution in MaxIm goes, over a year ago I took a couple
of high resolution (for film) images of M57 and NGC6543 on 100F. Sean Walker
offered to try his hand at extracting more detail from these shots with
MaxIm, and the first results were promising. As time went on, we found a
number of images could be improved, including a few planet images I took
under great seeing conditions. The deconvoluted results are also usually
slightly unsharp masked afterwards. And yes, I think that it's film use is
best targeted towards high-rez shots of the objects with high surface
brightness. It needs a strong signal.

The MaxIm deconvolution routine is mostly trial-and-error. Well, mostly
"error" <g>. Sean and I have settled on some basic settings to start of
with, but each film image reacts different. In many cases only the unsharp
masking feature works on the image, as some _very_strange_things and
artifacts can appear with deconvolution. One of the big +'s *when it works
well*, in addition to enhancing detail, is that the deconvolution routine
smoothes out the background nicely.

So far, the smoother the film grain the more likely the image will respond
to deconvolution. Provia 100F shines here, but I've also had OK results with
E200 and even at times with 400F. There are other programs with
deconvolution routines out there such as AstroArt and AIP4W, but so far I've
only worked with MaxIm on film and AstroStack for my webcam shots.

> I can relate to not wanting to setup with the IDAS filter after you are
> ready to go.  One of my favorite stories is when I shot a perfect 60
> minute shot of my focus star because I forgot to slew back to the target
> after achieving focus.  Its amazing I come out with anything.

Last summer under probably the best skies I saw all year, I took a 90 minute
exposure of the backside of my shutter --- as the film advance lever wasn't
completely cocked. You're not alone ;o)

> Congratulations on nice work.  The best film images of planetary
> nebulaes I have seen, perhaps the best period.

> Jeff Ball

Thanks again. But there's not many shooting bright planetary nebula
regularly with fine-grain slide film. I'm sure if others gave it a serious
go with long focal lengths, I'm they could do very well. I'd like to see the
results from somebody with better skies and optics than I have.

Take care,

John Boudreau
jeboud@attbi.com
http://home.attbi.com/~jeboud/astro.htm


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