Original/classic C8 SCT

[astrospace]

Hi Folks,

Anyone still got and use the classic C8 SCT?

I've got a friends original C8 here at home as the front plate has a light patchiness in a few places and I'm trying to sort it for him - also wanted to give him some suggestions on how to improve it. It comes on a fork mount & tripod with a wedge for equatorial use and slow motion controls.

Not sure if you can add a Hyperstar to the old models but then he isn't that much into imaging - more into drawing what he sees.

Cheers

Paul aka Astrospace

[scarp15]

I have one of these similar to the one you describe. In terms of the misty patch on the corrector plate, I have never touched mine, I just take it indoors (to a none hot room) after a session and remove the lens cover for a while to allow any condensation to clear. It will probably not affect the views anyhow.

This set up, with clock drive motor (9 volt battery) and fork mount, I find to be fine for visual observing, I have never tried to do imaging / photography. I did try and fit a dovetail once to fit it onto a CG5, however it can be a bit of a faf to obtain a dovetail that is compatible, but in the end I am happy with the setup as it is.

Might be worth checking / tweeking the collimation, usually a C8 holds its collimation very well, as long as you keep the perfectly adequate stock screws and do not fit bobs knobs (which might cause some slippage).

Best upgrade I did was to fit a Starlight feathertouch micro focuser, you can email starlight instruments, and purchase direct. Also fit a telrad, as of course this model precedes goto.

[michael.h.f.wilkinson]

My C8 has a different mount, but is also quite an old one by now (15-16 years). The only thing I like to do to the corrector plate is blow any dust off with compressed air, and gentle application of Baader fluid or a quality equivalent. For photography, I have used the 0.63x reducer corrector. A German EQ mount is better for photography

than the old fork type with wedge. Replacing the mount is costly, but it can improve the enjoyment a lot.

[astrospace]

Thanks chaps, the milky patch seems to be integrated into the corrector plate and I've tried using the Baader fluid which did seem to reduce the effect but there's still a faint patch. As you say I'm not sure its that bad to really affect the view and I know the owner doesn't smoke so I couldn't see it being that sort of deposit. He's also not really into photography so I reckon I've done about as much as I can. I doubt he'll change the mount but I did wonder about fitting a dovetail bar but as Ian said fitting one is not fun!

[michael.h.f.wilkinson]

This milky patch might be damage to the coating at that point. Recoating the plate is probably not worth it. Replacement is out of the question as corrector plates and mirrors are matched. The only effect will be a very slight reduction of contrast and brightness. Suppose 10% 0f the surface is affected. In the worst case this would increase reflection from about 0.5% to 5%. This yields a light loss of about 0.45%, or 0.0049 magnitudes. Not something which would keep me awake

[astrospace]

I agree - it isn't as bad as it looks but I think I'll suggest a focuser upgrade to my friend when I see him next.

Cheers

Paul