what kind of guide camera fit to guide scope

HST,

I have the Celestron CGEM Edge HD 800 which came with a 9x50 finder scope and I use it with an Orion StarShoot AutoGuider.  I had  to purchase an adapter to join them.  Not sure which scope you have, so I'll describe my setup and hope you can determine what you need.

Adapter: http://agenaastro.com/blue-fireball-t-t2-male-sct-male-m48-female-adapter-t-07.html

Finder Scope: http://www.opticsplanet.com/celestron-9x50-finderscope.html (discontinued)

Yes, that is a filter adapter, but it is threaded on both the inside and outside.
The SSAG connects to the T/T2  (M42x0.75) male thread on the smaller side of the adapter and the finder scope threads onto the SCT (2"x24TPI) male thread on the other side.  What you will need to determine is the specs for the female thread on the eyepiece end of your finder scope and find an adapter that matches.

I hope this helps!

One solution could be to use an off axis guide. One of the best (but expensive) guiding camera is the Lodestar X2, a lot of astroimager use it because it has high sensitivity. Another advantage is the diameter of 1.25", so you can use also an eyepiece adapter. But also other brand (qhy or other) produce good guiding camera. But I recommend…buy a monochrome one. :-)