[TrevorW]

Originally Posted by AstralTraveller

I don't understand that idea. The resolving power of a scope is directly proportional to its aperture, so masking the scope will decrease the resolution. It is also no use 'losing' aperture by increasing the size of the secondary obstruction as that increases diffraction and so reduces contrast. The only way I can see to reduce the amount of light without losing performance is to use a filter.

cheers,
Dave

please refer to these articles:

http://www.iceinspace.com.au/forum/a...hp/t-5877.html

http://hou.lbl.gov/~vhoette/Explorat...perture-s.html

http://www.cloudynights.com/item.php?item_id=548

http://www.astronomics.com/main/defi...f9lghe8/Page/1

Regards