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BackCG5 and C9.25 combination Next

I had heard stories of runaway slews, but it's only happened to me two or three times. The cooling process hasn't been a problem either. On week days I put the scope outside as soon as I get home from work. By the time dinner is finished, the scope has nearly always reached thermal equilibrium. I recall only two occasions in the first year when more time was needed.

Much has been written about image shift and SCTs. In one of the other SCTs I have tried I did notice slight problems, but that hasn't been the case with my C9.25. Focusing is easy and the 2” steel tripod legs are sturdy enough to support the weight of the OTA without a lot of vibration. When I began to use this scope

Starlight Instruments Feathertouch Focuser

forSchmidt-Cassegrains. Lower image is of

MeadeFlip Mirror.

for webcam imaging, focus became more of an issue and I decided to go with a third party dual-speed focuser. Again, my C9.25's focus system was quite adequate for most purposes, but I needed the fine focus.

Another thing to consider is that a Crayford type focuser can eliminate or at least prolong eventual SCT mirror flop by eliminating the need to constantly move the primary mirror back and forth.

From the first night on, I have always used a rough polar alignment, simply putting Polaris near the center of the polar scope hole. Actually, for visual use, this is not strictly necessary. There have been times when I've just set up in an area of the yard where Polaris is hidden by trees. Whenever this happens I just point the mount north, and it still tracks reasonably well. Of course a rough polar alignment is a better way to go. It would enable you to walk away from the scope and return 45 minutes later to find your target still at the edge of the FOV.

Since my first light experience was also my first experience, I had no basis for comparison andeverything looked great. Not many SCT first light reports spend much time on views of the stars, which are really the forte of refractors and other optical designs, but I had never looked through an apo or a Maksutov-Newtonian, so I didn’t know if I was missing anything.

It was early winter and I was astounded by the views of M37 and the other open clusters. Later I would understand that this scope doesn't quite produce the contrast or the pinpoint stars you would get with those other scopes, but the optics are not bad at all. On the contrary, they are excellent. It's true that you still won't get as wide a field of view as with the “slower” telescopes, but to see the Double Cluster through a C9.25 with a good 2” diagonal and a 30mm eyepiece is still an awe inspiring experience. The first time I looked at the Double Cluster using the C9.25 and an eyepiece that gave me a true field of view of 54 arc minutes, I immediately understood what the eyepiece reviewers meant by taking a walk in space. I would suggest to any new SCT owner that they replace the 1.25” diagonal as soon as possible. Until they do, they're really not getting the full extent of their scope's capabilities.

Also, with an SCT, you can get those panoramic views without breaking the bank. One of the advantages of an f/10 SCT is that you can take advantage of some of the less expensive but decent 2” eyepieces coming out of Taiwan and China. With slower scopes there won't be nearly as much edge-of-field distortion as with a faster reflector or refractor.

Saturn captured on 3/26/2005. Celestron 9.25" SCT with 3X

barlow in fair to good seeing conditions. Image is comprised

of roughly 1000 of 2500 frames, hand selected and

stacked in Registax.

I soon got over my initial fear of the collimation process. On the first day I decided to install Bob's Knobs, but the installation knocked the scope's optics so far out of alignment that I was forced to learn collimation then and there. It turned out to be simpler than I had suspected. Now, during nearly every session, as soon as seeing becomes stable enough, I put in a high powered eyepiece and star check the collimation, making adjustments when necessary.

There are general rules of thumb regarding magnification, but it's really a subjective issue. Image softness that I might find intolerable may be okay for someone else. And everyone's eyes are different. At any rate, for planetary observation with the C9.25, my experience has been that 133x to 150x are near optimum magnification levels on nights of average to good seeing conditions. I have, on rare occasions, been able to increase magnification to 250 comfortably, and even more for lunar observation.

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