It's all about the atmosphere

[Tonys]

Last Tuesday night I was looking at the moon through my 200p dob and for some reason it entered my head to try it with the 50mm aperture mask fitted. Suddenly all that image shimmer had gone and the detail was .... well actually very similar, although obviously dimmer. Granted that is was a very poor night for seeing, but it reminded me of how much we are limited by the atmosphere most of the time and why well corrected small scopes can appear to perform so remarkably well. The Questar 3.5 inch springs to mind as a very clever piece of marketing in this regard.

[starman1969]

I expect it may look too bright through such a large aperture scope, especially if not using a moon filter. Using the aperture mask sounds like a good idea for this.

[Moonshane]

I use aperture masks all the time. if the atmosphere allows use of full aperture it's much better for detail  as you have more resolution and brightness but the best and most consitently sharp views I have ever had of planets have been through my 16" dob masked to 170mm.

[Moonshane]

well, obviously not all the time. when observing solar system I mean.....and more often than not. for faint stuff it obviously gets removed