Posts Made By: Peter Froh

I'm grinding my first mirror, an 8 in Pyrex blank, hopefully to f7. I recently purchased a 14 in blank which I will probably grind to f5.

I was wondering if it's possible to make a truss dob that can be altered to use both mirrors.

I was thinking that I could make an interchangeable tailgate and have 2 sets of tubing, one for the longer focal length and one for the shorter focal length, and I'm all set.

Is there a lot of issues with using a large secondary mirror with a smaller primary mirror. I would obviously have to use a larger sec mirror for the 14 in.

I am hoping to save on some costs by making one scope that can accommodate both mirrors. Is it feasible? How about worth while? Any suggestions or comments from experienced people would be appreciated.

I attempted to find the answer to this question in the forms but could not.

I am building an 8 inch dob and have a 14 inch mirror blank that I will eventually be making a scope out of some day. I am not sure if I should be making the 8 inch dob with a 2 inch focuser for the sake of sharing the eyepieces with the 14 inch once it's made.

What are the guidlines/considerations when choosing the size of the focuser for your telescope?

Thanks!

I belong to the Fraser Valley Astronomers Society in Abbotsford, BC. We have lots of members who make mirrors and some who even have started businesses that aluminize mirrors.

We have one member who has lots of experience grinding mirrors by hand. He has put together a 12 page document that has helped a lot of people make great mirrors. Visit our website and look for the telescope making box on the left hand side (http://www.fvas.net), particularly Vic's mirror making link.

Good luck! I'm following Victor's instructions for my first 8" mirror.