Thanks you all the replies, I put together an aperture mask yesterday. Since the
seeing was soso late last night I gave it a whirl on Saturn, there was a definite
sharpening of the planet disc and ring system, and also a definite loss of resolution,
no banding on the planet disc or different shades in the ring system. As opposed to
full aperture where all these feature present them selves. Interestingly though the
cassini gap was slightly easier to observe with the mask. The background sky was
darker with the mask too.

Splitting double stars Castor and Pollux was visually easier too.

John, I'm looking into one of the new 16" GSO dobs, I figure if I can make an 80mm
mask for the 8" then I should be able to (maybe) make one of around 160mm for the
16".

Gary, ideally I would like to reduce it to an f/4 or there abouts. For wide field visual
and possibly imaging. The optics in my scope are fine in respects to why use an
aperture mask. I'm mainly just experimenting on cutting light down. I live in dark skies
and find at time the planets can overwelmingly bright. No question about it aperture
rules here too.

Anyways thanks for your thoughts guy's

regards,CS