While I can SEE Stephan's Quintet most any clear night at Chiefland Astronomy Village...bringing out any DETAIL still requires excellent transparency - even with a 28" scope...and CAV is in a dark blue region.
Once in a while we get a really special night and I was lucky enough to be looking at the Quintet there 3 years ago when we had just that -
a truly dark sky with absolutely perfect transparency!
I also found that the electronic gods had smiled upon my endeavor and the big scope was tracking solidly so I put my Mallincam in the focuser and the resulting image is here:http://groups.yahoo....ount=20&dir=asc
This is a single frame. Actually a hand-held digital camera snapshot of my 9" monitor screen. The iteration time is 56".
I've never been able to duplicate this. It goes to show what others have said. Seeing conditions are everything. I've even experienced nights when the Horsehead is totally invisible even with a 28" scope and Hb filter!
If the sky background is brighter that the object you're looking for, you won't see it with ANY sized telescope.
On the other hand - the BEST "eyepiece view" I've ever had of the HH was with a 10" Teleport! It was PERFECT....for about 10 minutes!
15 minutes later it was totally invisible, although the sky didn't LOOK any less-transparent.
As with the detail in Stephans' Quintet...I have never again seen the HH that beautifully, even with 4X the aperture!