Re: [ATM] What is that Image size in Calculations

["vladimir sacek" <vla@toast.net>]

Geogre Nikolidakis wrote:

> D=( L(D-I)) / F  + I
>
> Where   I =  image size , L = the distance from the Secondary to focal > 
> plane,  D= Primary Size , F= focal lenght

It would be good to replace D on the left side (diagonal's minor axis) with 
some other simbol, for not to confuse it with D on the right side (primary 
diameter).

> I am not sure what it means, for example I like to full illuminate a 2"
> eyepiece. Is that means the image size it will be 2"?

"I" is the field diameter you want fully illuminated.

> Also L = the distance from the Secondary to focal plane .
> The point for the focal plane it will be the base, I mean the low end of 
> the
> eyepiece ?

With most eyepieces it should nearly coincide with the focuser top when 
focused on a distant object.

Vlad

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