Celestron GPS11 with fungus

The correcter is not that hard to clean. Make sure you place the corrector back in with the mark on the correcter edge at 3 o'clock looking from front of scope. Mark the shimes placement and replace in the same spot. There is no need to remove the secondary.

Use 100% cotton balls on the mirror, wiping from center out to edge. There are many liquid cleaners altenitives. Never use a dry cloth/ cotton ball and blow off all dust first.

Lynn Krizan

Lynn K · Jun 19, 2026, 09:04 PM

The correcter is not that hard to clean. Make sure you place the corrector back in with the mark on the correcter edge at 3 o'clock looking from front of scope. Mark the shimes placement and replace in the same spot. There is no need to remove the secondary.

Use 100% cotton balls on the mirror, wiping from center out to edge. There are many liquid cleaners altenitives. Never use a dry cloth/ cotton ball and blow off all dust first.

Lynn Krizan

Thanks, Lynn. The idea of shims make me nervous but maybe i’m over thinking it. I’ll look at some videos

Lynn K · Jun 20, 2026, 03:50 PM

Both Celestron and Meade shimed the corrector plate. This was done to center the secondary, not the corrector. The reason the mark on the edge of the corrector needs to placed back at the 3 o'clock position is to rotate the secodary for best Sperical Aberration correction.

There should be a set of 3 shimes. There may be 4. Mark where each is placed and put them back in the same place. I have found Celestron doesn't do a great job of shimming to center Secondary/Corrector. It's good enough for visual. After all, It a spherical optical design and a sphere is a sphere. But for Hyerstar imaging I had to re-shim /center the corrector/secondary. That was recomented by Starizona.

The new Edge version has set screws as apposed to shims. A very needed upgrade. However It may be more difficult the turn the set screw to the same rotation, as opposed to putting the shims back in. Celestron seems to do a better job on centering the Edge secondaries. That because the secondary needs to be centered in the flattener in the baffle tube.

I have an older Carbon Fiber C11 & C9.25 and a Edge 8. The C11 collects dust and the Edge is only used for visual. I use the C9.25 on galaxies at a dark site. It doesn't get much use either. I mostly use refractors using narrow band in Bortle 7.

Lynn Krizan

Super helpful! Appreciate the notes. Well now it’s tempting to make shim corrector adjustments on my C8, I didn't know the factory shimming was an issue. It’s tough, i’m always gauging the risk/rewards from performing operations like this. My images come out pretty well for my standards, but maybe there's a whole other level of sharpness I could be getting in my images.

What are your thoughts on the HyperStar? I was considering getting another c8 or maybe a c6 and HyperStar but it sure sounds nice to not have to worry about collimating another system. Any suggestions on refractors? I’d like to get something for wide field use and open to really anything in the 100-500mm focal lengths. I keep looking at the 135mm rokinons.

Hi Paul, I started imaging with the original Celestron Hyperstar on a forked C8 (around 2004). The original didn't have any collimation adjustments and would ony cover a small chip. I later bought a Celestron CGE,C11 Hyperstar 2 combo from Starizona (around 2008). I origally only did Ha mono imaging. When I moved to the Hyperstar 3, the Hyperstar lens was wide enough to acomidate a filter drawer. At that time no one made them but Gerd Naumann. I got Starizona to make an adapter for it. I may have been the 1st Hyperstar user to use a filter drawer. It worked very well. Some time latter Starizona came out with theirs and the rest is history.

Pros and Cons of a Hyperstar: It's very fast at F2 with a larger aperture than refractors. Reflectors can be f4 to f2.8. It gathers signal very quickly, which I needed with my limited field of view. It's not easy to collimate, and my experience is when detached and replaced it does not hold collimation. Todays new tools can make that easier. Hyperstar is tring to make a mass produced SCT into a F2 astrograph. Not an easy task, but can be done. The RASA is an easier alternitive and designed with a single use. I still have the C11 and Hyperstar3, but it collects dust. If I was dust off the C11/Hyperstar, I would only do it with OSC and Dual Band filters on emission nebula mounted in my Pod. No break down or reasonably. If I was going do Fast SCT imaging at a dark site, I would go with a 8” RASA and OSC ASI2600MC. If you like challenges and you like fiddling, then you might enjoy Hyperstar. AT F2 all optical issues are increased. If you prefer plug and play, go with a small refractor.

I prefer fast refractors. I invested in a used FSQ106ED with the F3.6 reducer/flattener. I have invested in the expensive Tak 645 Reducer QE at 1k off from China. They have dropped in price, now that the FSQ106ED is no longer made. I also use at a dark site the FSQ85ED with the Tak RB-QB F 0.73x reducer at F3.9. (also no longer made). The Asia alternatives seem to get good results.

I read about bad results fro the Celestron dew heater placed on the corrector. It over heats and near imposible to equally distribute the heat over the corrector. It’s least distructive to place a dew heater in center od a metal dew shield.