Re: [APML] OT: Deep M81 (12 Hours) (My image...really!)

["Robert Gendler" <robgendler@worldnet.att.net>]

Bobby,
Deconvolution algorthms are complex mathematical formulas that
try to approximate what the image would look like without the blurring
effects brought on by seeing, mechanical and optical issues. Its much
more than a sharpening filter. It does an amazing job of tightening an image
but does come at a cost. The image needs to have good S/N as decon
will bring out noise in the image, particularly the background (mottling).
The stars will also acquire halos with aggressive decon. One thing I should
mention is that for an image to respond well to decon it must be oversampled
which is another way of saying it needs to be taken at long focal length, at
least 2000mm. There are ways to deal with the noise such as making a layer
with a nondecon frame to replace the background and stars. The Lucy
Richardson algorthms IMO are the best. I use CCDSharp (now free off
the SBIG site). I hope this helps.


Rob Gendler
email: robgendler@att.net
Web Site: http://www.robgendlerastropics.com
----- Original Message ----- 
From: "Bobby Middleton" <bobm@koyote.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, March 12, 2005 6:02 AM
Subject: Re: [APML] OT: Deep M81 (12 Hours) (My image...really!)


> Many of us film users may not be familiar with deconvolution. I understand
> it can be a powerful tool. Exactly what does it do?
> Bobby Middleton
>
> ----- Original Message ----- 
> From: "Robert Gendler" <robgendler@worldnet.att.net>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Friday, March 11, 2005 6:49 PM
> Subject: Re: [APML] OT: Deep M81 (12 Hours) (My image...really!)
>
>
> > Bobby,
> > Thanks. Those are deconvolution artifacts. I usually try to replace the
> > deconvolved stars with a separate layer (predeconvolved image) but
> > I was so busy with the rest of the image I sort of neglected to fix the
> > stars. I'm sure you know what its like....you work so many hours on
> > an image that I don't even want to see it for a few days <g>.
> > Rob Gendler
> > email: robgendler@att.net
> > Web Site: http://www.robgendlerastropics.com
> > ----- Original Message ----- 
> > From: "Bobby Middleton" <bobm@koyote.com>
> > To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> > Sent: Friday, March 11, 2005 6:31 PM
> > Subject: Re: [APML] OT: Deep M81 (12 Hours) (My image...really!)
> >
> >
> >> Truley one of the best M81's I've seen Rob. What's the bright
semi-circle
> >> loop with accompanying dark artifact on the right side of most stars
seen
> > on
> >> the high-res images?
> >> Bobby Middleton
> >>
> >>
> >> ----- Original Message ----- 
> >> From: "Robert Gendler" <robgendler@worldnet.att.net>
> >> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> >> Sent: Friday, March 11, 2005 5:40 AM
> >> Subject: [APML] OT: Deep M81 (12 Hours) (My image...really!)
> >>
> >>
> >> > Finally an image I can call my own <g>. This is a composite
> >> > image of M81 with data from both my 12.5" RC and a small
> >> > contribution from a 20" RC which I was trialing remotely at
> >> > New Mexico Skies. Actually the 20" data made a very small
> >> > contribution. The luminance is about 8 hours total and RGB about
> >> > 4 hours. RGB and 6 hours of luminance from Connectuicut.
> >> > http://www.robgendlerastropics.com/M81RCComposite.html
> >> >
> >> >
> >> > Rob Gendler
> >> > email: robgendler@att.net
> >> > Web Site: http://www.robgendlerastropics.com
> >> > _______________________________________________
> >> > Astro-Photo mailing list
> >> > Astro-Photo@seds.org
> >> > http://seds.org/mailman/listinfo/astro-photo
> >> >
> >>
> >>
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>
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