Hi raymo and Chris,
Many thanks both for your replies.
http://www.cloudynights.com/topic/43.../#entry5566084
I did the above "flashlight" test on this 70mm unit and it gave a 60mm image when measured with the ruler. I use this test for my binocs also, and the current Chinese binos are usually stopped down compared to the 1960s Japanese ones. They just don't make things like they used to, scopes or binocs.
I tested the same with my 60mm frac after I knocked out the baffle inside the draw tube (it also had a baffle ring inside the draw tube)and it then showed a 60mm image with the 3 spacer tab visible in the image. Before the focuser drawtube baffle was knocked out, the image was only 50mm and I couldn't see the spacer tabs. The baffle on the main tube of the 60mm did not act as aperture stop on this occasion, and it is a 60mm f700 Tasco, but the baffle ring in the focuser certainly did.
Using the test, I am pretty sure the baffle on this 70mm f500 unit acted more than being a baffle but an aperture stopper or diameter restrictor from 70mm to 60mm as well. As such, I like to reduce the baffle in the main tube, not to remove it, just thinking what is the easiest way to go about this?
I agree, in good quality scope, the baffle should not act as aperture stop, but this unit does. After all, this 70mm 500mm is not that far from dept store as it is mass produced under different brand names from Synta.
PS: Don't get me wrong, it also gives great views but it would do better as a true 70mm than stopped down 60mm I think.
Thanks again both for your replies.
Bill