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I removed the secondary mirror from the Edge HD 8" to try and figure out if it could be centered better. Now, I cannot get it back on. I didn't realize there's a piece that it's connected to underneath the corrector plate and it is basically loose so getting the secondary mirror screwed on to this loose, unattached piece seems impossible. It was so easy to remove. What do I do now? Has anyone ever done something like this and managed to get the secondary reattached? Thanks, Jerry |
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| Hi Jerry! I recently removed my secondary for the first time, and initially thought that I, too, couldn't get it to go back on. But then I noticed that there is a little tiny notch in the secondary housing that has to line up with a little tiny "knob" on the housing (to prevent it from rotating, I figure). Make sure they are lined up and then it should seat itself properly. |
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Oamaruastro: Hi Oamaruastro, OK, I see a tiny notch on the secondary mirror. but what I don't see is a notch on the plastic part inside the corrector plate. I see two areas that don't have threads, is that what you're referring to? I line up the notch on the secondary with one of those two areas without threads? I've tried 4 times to line up the notch with the unthreaded area in the piece behind the corrector plate. But it just won't catch the threads so that I'd be able to tighten it. How did you manage to do that? Thanks, Jerry |
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Here's photos of what I've managed to do:  |
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| Hi Jerry, I did this once, and had to fully remove the front mount piece with the corrector plate to reattach. Even though I got everything reattached without damage, I couldn't collimate to save my life. I ended up shipping it to Celestron who realigned and cleaned it. (not cheap, but not terrible) |
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Nick Grundy: Hi Nick, Yeah, I've concluded I have to ship it to Celestron. I've poured some $2500 into this scope and haven't gotten one image from it in the 10 months I've had it. If I had any brains I'd stick to refractors and be content. This scope has been nothing but trouble for me. I see so many good images taken with it and that motivates me to keep trying, but honestly, I may just donate it to an astronomy club and be done with it. If I try removing the corrector plate I know I'll just mess it up even more.. I hope you are well, Jerry |
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| After the edge, I sort of did the same. I only used triplets for about 6 months. I ended up getting the epsilon 160 though which has been a dream since. I’d take a break from reflectors and go back to them later when you are ready to change it up again |
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Nick Grundy: Hi Nick, I use both the Askar 130PHQ and the Esprit 100ED often and am getting the quality of images I want with both scopes. I love refractors. But I also want to image galaxies that are smaller than M51 and M31 and for that I don't know of any refractors that will sit on an AM5 mount (max 44 lbs payload). Money isn't an issue, but now that I've tried for 10 months to use the Edge and haven't gotten a single image with it, and now it's broken (when I unscrewed the secondary mirror it became detached from the holder inside the corrector plate which I now understand should not have happened) I think I should try another scope. Any recommendations for something F6 or faster with a focal length of 1300-1600? Jerry |
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Hi Jerry, not positive you're dealing with the same thing, but check this CN thread out: https://www.cloudynights.com/topic/720673-secondary-mirror-assembly-rotating-in-corrector-plate/ If the secondary mirror 'assembly housing' (see post #10) is loose, I was able to screw mine back in using rubber gloves to 'grip' the interior without removing the corrector. As I mentioned in my post to the thread, I discovered it was a fairly common issue when I contacted Celestron..... Cheers, Scott |
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Jerry, the Edge HD is a great scope for the targets intended, don’t ever get rid of it. Patience is the number one asset in any astronomer, fixing scopes is a life time routine, so consider this little hiccup part of you learning curve. That said, in the meantime if you can afford a RedCat71 go for it, this will solve many problems. You have to keep in mind that shorted focal length with low FR factor will allow for greater field of view making it easer to find more stars to start your night and a lot easer to focus on them. With both scopes now you’re able to see or image most targets. The problem with big aperture is that they will gather lots of photons all good and bad, so if your conditions are bad, your results will be bad, if the conditions are good your results will be amazing like the pictures that motivated you to buy the Edge, resolution in that scope is what defines it. Just look for the targets for it and only use it in good to excellent conditions. Any other bad conditions days, you can use the RedCat71. Pls don’t get me wrong, in good to excellent conditions, both scopes are amazing, it’s just that there are different targets for each of them. Later time, you can modify them with the reducers and Barlows to get other targets on each of them. In the matter of the problem in hand, there are few YouTube videos to help you with it. Hope you keep your passion in Astronomy and keep in mind that patient payoff. The hobby is challenging but have many benefits one been Neuro plasticity keeping your brain in Health. |
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I've considering doing this myself but opted against it as I want to check with a Ocal collimator before I do anything rash. I installed the dew heater ring and Bob's knobs during the summer and haven't really had a chance to image with it yet myself after owning it nearly a year. I only got a capable mount during the summer though. Been too busy with my refractor. I did come across Dylan O'Donnell's video about this exact thing and thought it might be of some help: https://www.youtube.com/watch?v=EcKQFutDEAw I can't recall exactly what he says during the video, but I think it shows the whole process from start to finish. |
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I've considering doing this myself but opted against it as I want to check with a Ocal collimator before I do anything rash. I installed the dew heater ring and Bob's knobs during the summer and haven't really had a chance to image with it yet myself after owning it nearly a year. I only got a capable mount during the summer though. Been too busy with my refractor. That’s the video I watched before I went ahead and collimated my C8. The instructions are clear, and the approach works very well (my collimation was nearly perfect after adjusting the mirror while it was outside the scope). |
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Oamaruastro: That's good to know. If I need to do more than adjust the screws I will re-watch that one myself. |
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Celestron has agreed to repair my Edge as it is still under warranty. Whew! Now the problem is shipping it with the interior piece of the secondary mirror assembly moving loosely around the tube. It can easily fall into the primary mirror if the telescope is turned the wrong way. I have no idea how Celestron is going to solve that one. I guess they could walk me through removing the corrector plate (as long as it doesn't void the warranty) I could reconnect the secondary, put the corrector plate back with their help and then ship it to them for final repair, cleaning and collimation. I'll see what they say now that they know about the shipping issue. Thanks everyone for replying! |
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A very happy ending! I finally managed to remove the corrector plate, gave it a good cleaning, reinstalled it using the matching notch that the factory put there and I got my first image, which isn't bad for a first start. I also finally figured out how to collimate it using the OCAL 3.0 collimator. Thanks all for your help and sympathy! Jerry   |
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It's great to know you've successfully aligned your scope. I also conduct annual maintenance on my C/8 and would like to offer some of my experiences. I prefer to replace the secondary mirror's three M3x12 tip-tilt screws with M3x12 hex socket head cap screws. Once the secondary mirror is clean, I fit the new screws. The gap between my C/8's holder and the secondary mirror's back measures loosely 3.35mm. To prevent any damage to the mirror, I use automotive feeler gauges to ensure a snug fit. Prior to removing the corrector plate, I take several precautionary steps. I mark the position of the glass and carefully loosen the top two grub screws by a quarter turn, making sure to note their precise locations for reassembly. I employ the OCAL collimator for initial alignment and am pleased with the results.      To make sense of all the pics is as follows: 1) Ocal collimator - This is the only mirror adjustment I've made. 2) 100 micron artificial star (daytime) extra defocused at 85' away from the telescope in my yard. 3) measurement of artificial defocused star in Skywave 4) Skywave analysis of coma - score of 9.6 from center (ok/good) 5) skywave analysis of PSF (good) 6) pre-shooting test with tri-bahtinov mask that evening (ok/good). Again the only adjustment I make was during the use of the Ocal Collimator. You may be able to see that both the Skywave coma and the tri-bahinov mask show a small improvement (touch up) in collimation could be made. Clear skies! |
