Thanks Andrew.
I checked my 70 degree 26mm E.P this morning and it has a 30mm field stop.
I doubt that I'll be wanting anything with a longer focal length for the present time, but it's good to know that after a certain diameter the field stop size will be important.
The skies here in Perth have been weird over the last few nights..........sometimes cloudy, but mostly hazy............which can be worse.
I'm dying to get a look at Saturn but it still rises a bit too late for me at the moment, and I have a large high house to the East of me which doesn't help.
I'm anticipating that planets will be awesome through this scope when seeing permits.
Rob.