Re: [APML] Medium format wide field scopes

[Matt BenDaniel <matt@starmatt.com>]

At 10:13 AM 3/28/2002, Chris1011@aol.com wrote:
>In a message dated 3/27/2002 10:46:10 PM Pacific Standard Time, 
>shekhar@prodigy.net writes:
>
>
>>Is this true for just red (H-alpha) or is that true for the entire visible
>>spectrum?  Is the problem with an uncorrected scope that it can
>>focus accurately within narrow passbands across the entire visual
>>spectrum, but it cannot focus different wavelengths together?
>>
>>In other words, if I use a 400-410nm filter on this scope, will the star
>>sizes be as good as the ones using a 650-660nm filter?
>
>
>The short answer is yes. The stars will be sharp. The long answer is that 
>the images will not register correctly because the focal length changes. 
>This can be overcome with software manipulation.

This kind of registration can be done easily in RegiStar.

>Also, you will miss a lot of photons, and you will be doing some very long 
>and painful exposures to register any kind of density.
>
>Roland Christen

--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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