20"-24" Mirror

[john_drummond (John Drummond)]

Hi,

I'm thinking about making a 508mm (20") to 610mm (24") f3 - f4 Newtonian. I'm wondering if anyone can point me to -
1. some mirror bland suppliers (I've Googled some already)
2. Someone/company that may grind the above blank
3. Perhaps a supplier of already made mirrors of this size and speed
4. Someone to aluminize (and possibly) coat the mirror

Regards

John Drummond
Possum Observatory Complex
International Astro Union Code: E94
Gisborne, New Zealand
E: 177d 53', S: 38d 38'
Email: john_drummond@xtra.co.nz
Website: www.possumobservatory.co.nz
Images: http://www.possumobservatory.co.nz/l...continuing.htm
Phone (mobile): 0275 609 287

[OICURMT]

A little bigger than you wanted, but hey...

http://www.astromart.com/classifieds...fied_id=769155

[clive milne]

John, some random thoughts:

A 20" f/3.5 will let you build an instrument that allows for 'feet on the ground observing'... It can also be built in a compact format so transport and set up is (or could be) a breeze. But, the qualitative jump in the observing experience that you get with a 24" telescope is significant.

Blanks can be acquired through Newport glassworks relatively easily.

If you are located in Australia, I would highly recommend Mark Suchting for the optical work.

Also, Wayne Saintee for the coatings.

btw) That 28" looks very reasonably priced... I would however, take the 1/8th wave spec with a very large grain of salt.

~c

[clive milne]

Another option to consider is making a pair of 16" binoculars using GSO mirrors... a pretty cheep option with some qualitative observing advantages over a monocular of any size.