Basically what the topic title says. I reinstalled my Parallax/CZ 11" F7.3 Newtonian on the AP 1200 the other day to measure the system up for another Telegizmos 365 cover and take advantage of the extended bout of good weather we are having here locally (with sometimes excellent seeing too...for around here anyway). It had been parked and covered in my basement for a couple of years.
Well the system ROCKS. Period.
I carefully collimated the system and the views of Jupiter and Saturn have been just flat out great. The mirror is quartz so it holds its figure pretty good during cooling but I can still get thermal plumes off the face. So I use the boundary layer fan to blow it off. And it works wonderfully. Sans fan on, I can see small pluming coming off the mirror with in/out of focus star images (basically a V shaped bites out of the rings) but the viewing is very nice with sharp detail on Jupiter and Saturn However, turning the fan on just seems to make the image "cleaner" with more "pop", especially at high power. It's quite repeatable too.
Before I did any collimation tweaking though, I was struck by the sharp detail on Jupiter but noticed the moons, while distinct disks, were showing a little flaring to one side during moments of unsteady seeing. Sure enough, a star test show a collimation issue and my Glatter tools showed the secondary was fine but the primary was off a bit using the barlow (the center of the shadow of the mirror's triangular center marker was ~3/8" off). This was easily corrected in less than a few minutes tweaking on push-pull screw set. What I found interesting was that the effect of the improved image collimation on the image of Jupiter was rather small and similar to the effect of the boundary layer fan. The effect was more noticeable on high power star images like the double double which now showed a nice airy disk and a good first ring that jumped around a bit but the dancing was now evenly distributed instead of bunched up on one side (the seeing actually let me see a distinct airy disk for extended periods, which for me is around 5 or more seconds at a time). So, I now really do appreciate the user friendliness of slower newtonian optics.
And boy, CZ makes some great mirrors and Joe at Parallax a very nice and sturdy OTA. Well done gentlemen!