Full aperature or off-axis

[AstralTraveller (David)]

I need to knock up a filter for my 10" GSO dobs (so we can his and hers scopes). I've got enough film to make it full-aperture but I notice many people make off-axis masks. Doing so drops the aperture from 10" to 4", and hence the theoretical resolution drops to 40%. On the other hand there is no central obstruction, which is 26% on the GSO. Does that offset what you lose?

Which way should I jump?

[Merlin66 (Ken)]

Unless you have fantastic seeing conditions during the day, the maximum solar observing aperture seems to be around 100 to 150mm.
An off axis mask of similar size will probably allow you to see and record all that's there....
( I used a full aperture white light filter on a 12" Lx200 for a while...it was very, very rare to find the results much better than the 100mm refractor I also used....)
HTH

[Steffen]

I suppose if you added a narrow(ish) band filter like the Baader solar continuum into the mix you could both cut down on the light as well as improve contrast and reduce atmospherics.

Cheers
Steffen.