Re: [APML] Achromats?

[Matt BenDaniel <matt@starmatt.com>]

Blair,

That won't work well.

1. Doing that will bias colors in favor of the in-focus channel (i.e. green).
2. You lose signal to noise ratio in the L channel because you throw away signal (in the unused channels).
2. The green channel is often noisy.

Matt

At 10:30 AM 7/8/2002, Blair Batty wrote:
>Relatively inexpensive achromats aren't used in
>astrophotography because the various colours are
>out of focus to each other (you know what I mean).
>
>Why couldn't you use an achromat to take a photo;
>focusing it sharply with one central colour (perhaps
>using a filter over your eye so you only focus on 
>one colour). Then:
>
>1) Digitize
>2) split into separate photos of RGB
>3) Go into Lab mode and use the "in-focus" colour 
>     as the L channel.
>4) restack in registar
>5) combine the original colour information with the
>      "in-focus" L channel.
>
>I admit I don't know what I'm talking about. But I wonder
>if something like this would allow taking sharp photos
>with a cheaper telescope? There are all those fast,
>wide, inexpensive Chinese 'scope available now...
>
>Sincerely
>Blair Batty
>
>
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--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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