Re: [APML] Flawed astro slide - anybody take a look?

[Matt BenDaniel <matt@starmatt.com>]

Emmanuele Sordini wrote:
> 
> Hi list,
> the above mentioned slide is a short exposure (something like 10-15 secs)
> taken by a friend of mine with a fixed-tripod camera and a Nikon widefield
> lens (must be something like a 28 mm). You can view it at:
> 
> http://lonestar.texas.net/~genehorr/013225-mc.jpg
> 
> thanks to Gene Horr for hosting it. Any hints/ideas as to where those
> "concentric" patterns could come from (development, crippling, mishandling)...?

They look like newton rings.  They happen if you place the film flat to
glass while scanning it.  You need to lift the film off the glass or use
some newton powder.

There are other possible causes of the rings.  Gaussian blurring in
Photoshop can cause it.
-- 
Matt BenDaniel
http://starmatt.com

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