[ATM] What is that Image size in Calculations

["Geogre Nikolidakis" <geoniko@otenet.gr>]

Hi all

This is my first mail to the list so let me introduce myself

My name is George Nikolidakis and I am an amateur astronomer from Greece 

Reentry I manage to finish a permanent roll-off observatory to house a 12"
LX200

Mainly for astrophotography purpose.

You can take a look for the observatory here
http://www.geocities.com/ginik_gr/NewObservetory

And also in some deep sky photos here
http://www.geocities.com/ginik_gr/EosDeepSky.htm

My problem is now that I don't have any telescope for optical observation
(star parties and campaigns)

So I decided to order a 20" f/4.5 primary from Pegasus optics in order to
build a truss tube telescope.

In my calculation about the size of secondary mirror one of the parameters
is the image size.

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

 

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"?

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 ?

I have a few others questions but in the next days ... -:-)

Thanks 

George Nikolidakis

 

 

 

 

 

_______________________________________________
ATM mailing list http://www.atmlist.net/