[alpal]

Originally Posted by alpal

Just checking different collimators -
it seems like the Howie Glatter is the best:

https://www.siderealtrading.com.au/p...2%80%B3-650nm/

15 arc seconds ?

Actually - that advert is wrong!
0.1 inches at 20 feet or 240 inches -
Tan-1 0.1/240 = 0.02387 degrees = 86 arc seconds.

Something to think about but that is the best you can get
and has been found to be perfect.

cheers
Allan