The wrong way to store SCTs

[MikeP]

For various reasons, I had not used my C11 since last November, so during the recent clear spell I decided it needed an outing.

Only a few days earlier Bobs Knobs had arrived and I'd installed them, but only done a rudimentary collimation indoors. When I took the scope out, predictably it was out of collimation, so I set to. Despite easily getting the de-focussed star's diffraction rings to look pretty concentric, the focussed versions were not points of light.

Rather than keep fiddling, I decided to take a break and just enjoy the view. I eventually became aware that something was not quite right and after checking eyepiece and diagonal, I looked down the tube. The secondary seemed to have a large blob of frost on it. I hadn't been using the dew shield because I'd been collimating, but the heater strip had kept the corrector clear. Puzzled, I decided to pack in for the night.

Next day, I looked into the tube and the "frost" was still there. To cut what is becoming a long story short, I discovered that the frost was in fact grease. Unfortunately, I'd stored the C11 vertically with the primary pointing down. I'd made matters worse while I was installing Bobs Knobs by turning the focuser from one extreme to the other and back again - this being a suggested way of ensuring that grease was evenly spread to enable smooth focussing. If you Google C11+secondary+grease (IIRC) you'll find I'm not the only idiot in the world.

The C11 came from David Hinds via Bern at Modern Astronomy. Bern was very helpful and David Hinds was prepared to take the scope back and clean the secondary, but since I'd had to remove the corrector to check the mirror and it didn't seem to much harder to remove the secondary and wash it, I decided to do it myself.

I can report the secondary does not have grease on it any more and the C11 is now sitting HORIZONTALLY in my study awaiting a clear night so I can re-collimate.

Hope that prevents anyone else joining the "dripping grease club".

Mike

[MartinB]

That's a very helpful post Mike. Well done for sorting that out. I could so easily have done that. You would think manufacturers would warn about this.

[MikeP]

I agree Martin. However, David Hinds had never heard of it happening before, so perhaps I was just unlucky.

Mike

[GazOC]

Cheers Mike, thats how I store my SCT/ Mak...I'll look out for that problem.