Re: [APML] Recovering poorly focused images

[Emmanuele Sordini <vega@bloomingstars.com>]

Hi Chris!

At 05.45 18/05/2004 -0700, you wrote:
>Emmanuele,  fixing bad focus on film images is not as
>simple as on CCD images such as using deconvolution or
>sharpening.  The problem is the film imags have for
>one, a high level of saturation in the core of the
>stars and data is usually lost here.  The PSF is
>complex for star images with film as well, not usually
>following a precise gaussian distribution.  There are
>only two solutions to this problem.  One, is desparate
>but has saved my rear on numerous occasions.  Using
>photoshops erode filter, you can SOMETIMES recover
>large bloated stars by shrinking them and not terribly
>rendering artifacts in the subject.  Apply the erosion
>filter and fade (under edit) some percentage starting
>at say 50%.

Thank for your suggestion: I will make the most of it when I manage to get 
my negatives scanned.
Frankly, I didn't think things would be so complicate with film. Basically, 
I thought there wasn't much of a difference between a film and a CCD image 
(except for the grain, perhaps) as soon as the former is digitized.

>Other wise option 2 - grit your teeth and
>chalk that one up to learning and retake the shot.

Well, that's another story; it's not a matter of learning to shoot, but of 
paying the utmost attention and trying not to be clumsy every once in a while.

Clear skies
Emmanuele

_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo