My Celestron Ultima 11" Schmidt Cassegrain telescope was originally built in 1995, and while the optical tube was in great shape, the original fork mount was getting pretty out-dated. It was difficult to assemble and almost unmanageable by one person alone. On top of that, it only had a simple clock drive for star tracking. While thats fine for basic viewing, its woefully inadequate for astrophotography. It was definitely time for an upgrade.
I chose to get a new Celestron CGEM computerized german equatorial mount. This would replace the old and heavy bolted on forks for a lightweight dovetail bar that simply clamped into the mount. I triple checked that I would be able to switch from the fork to a dovetail, made a list of everything I would need, and placed my order. Adorama shipped the order surprisingly quickly and before long I had a huge pile of boxes in my living room.
The boxes look pretty bad but that was exaggerated by the sleet coming down while going from the the truck into the house. Thankfully it all was packed extremely well and made the trip without any damage.
I opened up the CGEM box first, and my immediate impression was that it's extremely substantial and well built. Pictures don't do this thing justice - I firmly believe that if left outside during a nuclear attack it would remain intact. Considering it needs to hold the OTA plus camera gear and any accessories it is a crucial part of any astrophotography setup.
After getting the tripod and mount together I unpacked the new dovetail bar and got down to removing the optical tube from the original fork mount it was on. This was surprisingly easy as it is simply attached with four bolts at the base of the tube. I had to be very careful removing the original mount without scratching the coating on the optical tube - luckily it came out with only a few nicks.
Now that the tube was off the original mount I also removed the accessory bar and finder scope so I could give everything a good cleaning before assembly. Attaching the new dovetail bar provided me with the only 'gotcha' moment of the entire process. It seems new Celestron OTAs use different thread sizes for the forward and aft mounting bolts, so two of the four supplied bolts wouldn't fit. A quick trip to the hardware store and I was back in business.
The original mounting bolts were long enough that without the mount they would screw down far enough to make contact with the mirror itself. Not good, so I'll need another trip to the hardware store for some shorter ones. You can see bolts sticking out of the back of the tube in the photo below.
Standing at 6'6" tall I am very pleased with the eyepiece height when the tripod is fully extended. While I don't plan on doing much viewing myself it is nice to have things up at my height.
I re-mounted the finder scope and balanced the entire assembly using the 17lb and 11lb counter-weights. With everything setup the new equatorial mount is smooth as silk, I am thoroughly impressed. Unlocking the clutches I could move the telescope around with one finger and no slack in any direction.
Next I have to get the telescope out in the field on a clear night for a good practice session. I have to dial in the polar alignment which will be easier than before but still essential, as well as explore using the hand controller and Go To features. I'm very excited and checking the weather daily, but it being March will have to be patient.
I plan on sharing my journey as I learn more about astrophotography, so I will be posting more frequently as it warms up - stay tuned.