Celestron OTA cleaning

[Teal Rain]

Morning all

First time poster but a long time reader.

I recently got my C5 white OTA out of storage and found that some of the focuser lubricating oil has seeped onto the side of the mirror. It looks like the mirror end of the tube is held on by four allen bolts however these are secured on the inside by four nuts. So if I loosen the bolts the nuts will fall into the tube.

Does anyone know who would be the best to contact to get it cleaned up?

Cheers

Mark

[Andrew*]

I've used Viking Optical in Glasgow on a 4" lens. Very reasonable charge and they did a brilliant job on the lens, with reliable service to boot.

Andrew

[Peter Drew]

Hello Mark. I think you will find that the rear cell of the C5 is not meant to be removed, as you have noticed, the nuts would fall off and you couldn't replace them. In most SCT's and I expect the C5 is the same, access to the optics is through the front corrector plate. This plate has to be removed by unscrewing the screws that attach the corrector retaining ring. Mark the plate's orientation before removing as this is important for its relationship with the primary mirror. Cleaning the mirror in situ might be a tricky business, a decision might have to be made as to whether the problem is bad enough to risk making it worse. If bad enough to try this it would be best to remove the complete mirror assembly. To do this, you need to undo and remove the focusing knob, then reach inside the tube from the front and remove a circlip on the front of the light baffle tube, the mirror assembly will then slide off and can be withdrawn by turning the mirror through 90 degrees vetically so that it clears the front cell by way of the two slots machined in it. This is quite easy to do on an 8" but you will need small hands and plenty of care on a 5".

[Teal Rain]

Hi Andrew and Peter

Thanks to both of you for your replies.

Bit annoyed with myself that this problem has occured. I kept the scope sitting on the corrector plate end cap for a while so it's a problem of my own making! I've contacted BCF as they did a clean on an old C8 a few years ago. If they can't do anything I'll attempt your suggested method Peter - trouble is I don't have small hands!

Cheers

Mark