Bringing my CPC 1100 into the imaging fold

[kirkster501]

Hi all,

Getting on nicely with my HEQ5/ED80 combo as a beginner. I would now like to use my much-loved-for-visual CPC 1100 for DSO imaging as well (already use it for planets). Now, I know about field rotation etc. So whats the max exposure using the CPC you think at prime focus? I am interested in AP for smaller objects for the CPC like the Ring Nebula, M13 and double stars. Maybe lot of 30 second exposures perhaps? What's do you think guys?

Thanks, Steve

[michael.h.f.wilkinson]

For DSOs the CPC1100 has several problems, first of which is its focal length: 2800mm. The old rule of thumb on film for a stationary camera was 1000/ focal length in mm, yielding 1/3rd os a second before star trails set in. A tracking alt-az mount allows longer exposure, but not that much. Even on an EQ mount guiding that focal length is going to be very hard. The Mesu mount seems to be up to it, but F/10 is not really good, although with a focal reducer you get F/6.3 (though some say F/7 is more accurate). For DSOs you really need speed, not high magnification (except on some planetary nebula).

[kirkster501]

Thanks Michael. I am going to give it a whirl anyway - next clear night and have a play around. The CPC combined with my nice TV EP's is a lovely telescope and is good for webcam planetary. I am sure I'll be able to get something on it for DSO.... fingers crossed !

[michael.h.f.wilkinson]

Why not try one of the high-surface brightness planetaries (there are quite a few). You might be able to use a LX-modded webcam for that (never tried but I might).

[riklaunim]

Old webcams - are old and becoming a part of the history.

CPC can be used for planetary/lunar imaging, but best thing would be to add an EQ wedge allowing better planetary imaging and also DS imaging without field rotation. On the other side 11" SCT is quite hard to use for long exposures DS imaging. The focal length even with focal reducers is long, and you need good guiding for it. I've seen some CPC DS setups with a wedge but it won't be easy Maybe a f/3.3 reducer and a small chip - like a Brightstar Mammut camera (+ external guiding)? Other solution would be to use f/6.3 reducer/corrector and a big pixel camera (or pixel binning). The f/6.3 reducer would allow using also an off axis guider for guiding.

[kirkster501]

Thanks guys. Buying a wedge is out of the question for me until i can mount the CPC permanently on a pier (at my next house). For now I would rather invest that money in my mobile AP rig. I will see how I get on with stacking loads of short 30Sec exposures on stuff like M1, M13 etc.

[Freddie]

Give it a go. Before I got my MN190, I had a go using my CPC9.25 and found 60 second exposures stacked in DSS (which takes care of the field rotation) gave some quite nice results given the kit being used.