The Ross Null Test

[Glasspusher]

Great to see people making mirrors on SGL, and being helped by those who have been through the process in the past. For anyone thinking of making a mirror for the first time, the business of testing the mirror can seem a little daunting. I recently came across a lens on a well known internet auction site that might be suitable for testing mirrors up to 12 inches in diameter with a focal ratio of 5 or more. The same lens could be used for faster mirrors if they were smaller. The lens can be found here:

http://www.ebay.co.u...=item1c2a2def68

I should point out that the lens would need to be tested prior to use. For anyone interested in trying out the test I have put together a few notes: http://www.nicholopt...s Null Test.pdf

John