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Baffle tube removal on C6-SCT

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#1 Sean13

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Posted 25 February 2013 - 03:37 PM

I am having an issue with glares in my photos that have bright stars with my C6, and after doing some research I believe its related to some scratches and grease I see on my baffle tube that goes thru the primary mirror. I would like to pull it out and clean the grease and repaint it with a good flat black to see if this cures the problem, but I'm a little confused as to how it comes out. I've never taken apart a telescope OTA so help me out here.

#2 Geo.

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Posted 25 February 2013 - 04:04 PM

Celestron uses two methods of fitting the baffle tube.

The one I've seen on C5s (US built) is that the tube threads into the rear cell with thread lock applied. Then the ring nut for the rear port with thread lock applied is threaded on the tube section that protrudes through the rear of the cell. Disassembly involves removing the rear cell from the main tube and heating it in the oven until the the thread lock softens and permits unthreading the nut and tube. 250F seems to work.

The C9.25 is similar but the part of the baffle tube that is positioned in the rear cell is not threaded. It is retained from rotating with thread lock. The rear port nut is then threaded on with thread lock and also has a set screw.

So you're looking at a fairly extensive tear down. Not sure you want to paint the section were the primary carrier slides as it may interfere with focusing. Anyway when you are working at infinity the primary is pretty far forward on the baffle tube. If you want to experiment why not just pull the corrector and apply some flocking materail to the section of the baffle tube in front of the primary retaining clip.

#3 Sean13

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Posted 25 February 2013 - 04:10 PM

I have thought about that, and likely will do that to confirm this is the problem, but it still remains that flocking isn't a great way to solve the problem and the tube should be painted to avoid a loss of illumination at the edges of the field. Sadly I didn't think it was that complexed to remove it. Looks like I might be trying to work with the tube still attached.

I have some scratches it looks like on the very tip of the tube, which wouldn't get covered up with flocking. So I'm not sure flocking would cure anything besides the smuge of grease on the end of the tube.

#4 Sean13

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Posted 25 February 2013 - 04:31 PM

Is the tube solid enough for me to take the front glass off and clean the grease and maybe dab some flat black paint on the scratches?

#5 rmollise

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Posted 26 February 2013 - 07:37 AM

Is the tube solid enough for me to take the front glass off and clean the grease and maybe dab some flat black paint on the scratches?


Yes. Just don't wind up dabbing paint on your primary mirror. That will have more effect than a few scratches... ;)

#6 Eddgie

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Posted 26 February 2013 - 09:00 AM

Would you be a little clearer?

Is the grease on the inside of the baffle, or the outside?

There is supposed to be grease on the outside of the baffle.

Also, it is very unlikely that you could have scratches in the baffle that were serious enough to cause an issue with imageing. If you did, my qustion would be "were did those scratches come from?"

If you see anyting in your image, my personal recommendation would be to look very hard for a cause other than the baffle.

If you have some images that show the problem, it would be good to post them so we can see if we can diagonos the problem a bit better. There are many other things that cans cause issues that show up in images.

Posting a picture of the scratches would also be helpful.

You can open a can of worms by taking the tube OTA tube off of the mirror cell. Alignment is tedious because any tilt in the tube will cause the focal plane to tilt.

I would take every effort to eliminate every other possible cause before resorting to this step.

#7 Sean13

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Posted 26 February 2013 - 06:18 PM

The grease is on the inside of the baffle, I'm not talking about the grease for the carrier. This honestly looks like someone with a greasy finger stuck it down the baffle tube from the front is the best I can describe it. I'm having trouble getting any descent pictures of it but I'll try with a better camera tomorrow.

The scratches looks like where the inside paint and outside paint come together, but not very good. I did buy the scope used, but it seems unlikely the person I bought it from would have been messing around in there.

#8 Eddgie

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Posted 26 February 2013 - 10:32 PM

Sorry to hear that.






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