This is the first of a series of reviews planned for my new Celestron CGEM mount. I had my eye on the CGEM ever since it was first announced by Celestron. Some of the attractive features were its payload, Permanent Periodic Error Correction (PEC), new All-star polar alignment, and its ability to track well past the meridian before the scope needed to be flipped. I received the CGEM on Monday of this week (9/14/09) and had it fully assembled within an hour. Part 1 of this series is my review of the ordering process through the final assembly. I hope you find my CGEM review useful! Please feel free to add comments or questions at the bottom of the page (“Leave a Reply” section). Note that registration is not necessary to leave a comment.
Ordering the CGEM
I bought my CGEM through a long-time favorite dealer- Orion Telescopes and Binoculars. This is where I bought my first serious telescope about 20 years ago! Although they have their own line of telescopes and equipment, they also sell many Celestron products including the CGEM. I chose the 9.25″ SCT version due to its popularity as a great optical platform for planetary imaging.
The entire ordering process was a breeze. I found that their system was quite sophisticated and I was comfortable making such a large purchase online. Here is the telescope I ordered: Celestron CGEM-925 Computerized 9.25″ Cassegrain Telescope.
Receiving the CGEM
I had been tracking the shipping and delivery status through my account on Orion’s website. The packages were delivered on they day that they specified. There were five boxes total. One each for the optical tube, CGEM, tripod, extra counterweight, and the AC adapter. Note that if you are going to buy the CGEM, the AC adapter is optional. It only comes with the 12-volt adapter. You can purchase the adapter from Amazon quite reasonably though: CGEM AC Adapter here.
All of the boxes were in great shape with the exception of the tripod box which had some minor damage to the the cardboard flap. But there was no damage to the tripod and accessory tray since they were packed in their own double-wall cardboard boxes. In fact, everything was very well protected with heavy cardboard and foam. The CGEM mount was even packed in triple-wall cardboard! Here are some photos of the packages:
Assembling the CGEM
With the help of my dog Sirius (very fitting name, eh) watching over everything, I assembled the entire telescope in about an hour. First, I set up the tripod. It comes fully assembled so it’s just a matter of spreading the legs apart and raising them to the desired height.
Then the CGEM mount was installed next. The azimuth adjustment knobs had to be attached first and then the mount was set onto the tripod. It was secured by the knob on the underside of the tripod. The accessory tray and counterweight system were installed next. Here is the CGEM up to this point:
I want to note that any pictures that I have seen (including my own in this review) do not do this mount justice! It is MUCH beefier than it looks in photos. It’s really an impressive-looking piece of equipment in person. I noticed how substantial the CGEM was when I pulled it out of the box. It is heavy! I owned a Celestron CG5 a couple of years ago but it pales in comparison to the CGEM.
Some have questioned whether the CGEM’s housing is plastic. It may look like that in pictures, but it is definitely made of metal. It has a nicely textured finish and very cool-looking metallic orange parts. Yeah, the CGEM is a beautiful mount!
The last part is mounting the optical tube. The CGEM has a nice wide and sturdy mounting platform for the dovetail bar. It is a much better system than my CG5 was. There are two mounting screws with knobs that open both sections of the mounting platform and the dovetail bar slides in smoothly and locks firmly in place.
The visual back came already installed. I finished up the assembly by adding the viewfinder, star diagonal, and eyepiece that came with the 9.25″ optical tube. And last, I plugged in the hand controller. Here is a photo of the final assembly with me standing there (ugh!) for visual reference to the size of the CGEM.
Playing with the CGEM!
I spent the rest of the evening familiarizing myself with the CGEM. It goes without saying that it was a cloudy night. This is expected with every new telescope. All astronomers know this. It’s a well documented curse. But that didn’t stop me from using it! So I plugged it in and set up my local time and location and did some slewing. The mount is very smooth and is fairly quite at most slew rates. There are nine speeds total to choose from. The highest rate (9) is somewhat loud but I don’t think it’s an issue. Here is a video of me slewing the CGEM in RA and DEC. Note that the slew rate is at its highest setting of 9. Be sure to turn up the sound to hear what it sounds like:
All Pros and No Cons?
Not exactly. No matter how much you spend on a telescope, there is always something that isn’t quite right. With my CGEM, there were a couple of things that were a bit of a concern (although not major). For instance, the hand controller cord seems too short in some instances. I have seen other reports of this. Fortunately you can order an extension cable for the CGEM hand controller here at AstroPhotography Tonight.
Also, the manual refers to index marks on the RA and DEC axis that you line up before starting your alignment procedure. Oddly, on the DEC axis, one index mark is on the back side of the mount and the other is on the front! I wonder if they decided to place the index marks on the back (so you can see both RA and DEC marks on same side of scope) but accidentally placed the one on the front out of habit. It looks to me that the collar can be spun around 180 degrees and it will correct that. I will probably try it! But even if it doesn’t, it should not be a problem because there is a screw hole located below the front index mark that will serve as a reference. As you’ll see in Part 2 of my CGEM review, this didn’t phase my alignment because the goto was spot on! I was very impressed with my CGEM’s performance on the first night out!
My first impression of the Celestron CGEM was a good one. It is a very solid and sophisticated mount. I still have much more to learn about it and I look forward to exploring its capabilities in astrophotography (planetary and deep space).
Part 2 of my CGEM review will cover my first night out with it. Keep checking back here on AstroPhotography Tonight for further coverage of the CGEM. As mentioned earlier, if you have any questions or comments, please post them in the “Leave a Reply” section below. Also, I have added a survey below to find out if this review was helpful to you.
Clear Skies! Ray Shore