Image of the day

From the
ATWB Customer Gallery

Solar Active Region AR 2741

My Account

New to Astromart?

Register an account...

Need Help?

Newtonian Project

Started by randallrp, 04/16/2002 12:55PM
Posted 04/16/2002 12:55PM Opening Post
Can anyone suggest a supplier of parts for a 6 to 8 inch Newtonian project I am considering. I would like to build it in an aluminum tube and use an EQ mount. Also any tips or resources I could investigate would also be appreciated.
Is F5 too short of a focal length? Are F5 mirrors available? I am basically trying to find out what it would cost to build a somewhat premuim scope and am also wondering what the advantages over an import Newtonian are.
Also how would such a scope compare to a Mak Cassegrain?

Posted 04/16/2002 02:29PM #1
If it's premium quality you want, I suggest a spider and secondary from Protostar and a primary from Mark Harry

if you can live with f/6 or otherwise get Mark to make you an f/5. Otherwise, I hear Robert Royce

makes a good mirror also, but the price is rather higher.

A well-made Newt should outperform a quality MCT of similar aperture due to the larger obstruction on the MCT, and if properly made it also should handily outperform Chinese import scopes of the same size. Having said all that, the best MCTs can be quite impressive, and don't forget the Mak-Newts, either.
Posted 04/16/2002 04:37PM #2
For what it's worth, the attached photo is my 8"f/6 that I recently completed. The mirror is homeground from 7/8" plate glass. The tube is sonotube that I stripped away the wax inside and outside and then fiberglassed. The focuser is 2" JMI, 1.65" diagonal. The mount is TAL2-M Russial GEM. At a recent starparty I compared imaged of Jupiter side by side with an AP 5" f/6, the new one. I will readilly admit that the contrast was slightly better in the refractor, but not 3000.00 worth!! Sharpness was about equal in both. Image brightness was much higher in the 8", as expected. I would consider my mirror good to excellent, but nothing to rave about. Can't wait to get my newly finished 10" mirror in a tube unit!

Attached Image:

Walter's attachment for post 61497
Posted 04/17/2002 03:53PM #3

If you want to keep your cost low, check out the Sky and Telescope travel scope series that started I believe in Dec. Since then they've done an article on a diaginal holder and a mirror cell. Both looked good to me, and wouldn't have to be in a travel scope, would work just as well in a tube.