Re: ATM designing an astrograf

[Aplanatic@aol.com]

Frédéric Butz wrote:

> I plan to design an f/5 or f/6 astrograf wich can take 6*6 pictures. Do 
>  someone have an idea where I can find plans or ideas for it ?

Assuming that you want a medium format (6 cm x 6 cm) instrument, that's a 
pretty open question.

What aperture size and focal length do you have in mind?

How much vignetting are you willing to tolerate at the corners of the film 
frame?

Will you be transporting the scope?  How heavy can it be?

Do you want to use an off-axis guider?

Do you want a Newtonian configuration, Cassegrain or other?

Will you be making the optics?  Can you make lenses?

Will you be making the mount?  If not, what type of mount will you use?

How good do the star images in the corners need to be?

What film transport device will you be using?

A medium format astrograph is a complicated system with many tradeoffs and 
the "right" design is impacted by many factors including, but not limited to, 
the above.

Dave Rowe.