Hi Bob,

I bought that 60mm GS from AP three years ago for the SDF and 130. With a
Tak 5mm Guide eyepiece, I'm at 140x, which does begin to get dim for
guiding. I'll try to keep within the FOV AMAP, good tip. The 140x works out
to be about 5x the focal length in inches with the 130f6, so it looks like I
should use 200+ with the 155f7. May have to upgrade as you say.

For all you ST4 users, isn't the 60mm GS adequate for autoguiding for 155f7?
Eventually I'll have to get one, but I want to experience the pain of manual
guiding for now anyway.

Thanks, Stephen

A 60mm guidescope can certainly work for manual guiding, though my

preference

has been 80mm. I prefer to select a guidestar that is within the
field of the image, to minimize the chances of field rotation (good polar
alignment is important). An 80mm just gives you a brighter selection of

stars,

at a high enough magnification (200X or higher) to make guiding easier.

In any case, a 60mm guidescope is pretty cheap and you can always upgrade

later.

Bob Luffel