Eyepiece projection problems

Yes Dave, what CJ is doing is really Afocal coupling, not eyepiece projection.

The problem is the design of his camera lens. Wide ratio zooms use a retrofocus design in which the front element of the lens can be way ahead of where the "virtual" lens is. CJ's lens has a focal length of 5.7mm at its widest, and ideally you'd put that lens, 5.7mm from the sensor, right up close to the eyepiece, but he can't do that because lots of the lens is in the way. Now he could zoom in until the "virtual" lens is closer to the front of the real lens and indeed a better coupling will be possible, but in doing so he will have upped the magnification to the extent that everything will need to be lined up perfectly and kept perfectly still.

Nice shot BTW, i'll bet it wasn't taken with a camera with a wide-ratio zoom lens

Hey CJ, sorry if my explanation is too technical - do try your non-zoom camera - I suspect it may work better for you!

Re webcams, have you taken the lens off your webcam? The idea here is to use the 'scope as a replacement for the lens - you get loads of magnification by virtue of the long focal length of the 'scope imaging on the small area of the webcam chip. The magnification is so much that the biggest problem I find is actually finding anything, then getting it in focus!

Hi Paul

thanks for that, I think I understand what you are saying.
I think in the long run, it'll be better for me to go down the webcam route, but I will try the other camera at some stage.

I'm slightly embarrased at my lack of photography knowledge as I work in web programming & deal with Hi res photos from photographers on an almost daily basis but know nothing about how to take a good image apart from point and shoot, lol.

My current webcam has a 1.3mp CMOS chip rather than a CCD chip , I haven't taken the lens off it yet. Assuming I can do that ok, and can attach it somehow to the focusser won't it just take an image of the secondary mirror supports as this is all I can see when looking in there?

Thanks for you help, once again

cheers

Fair enough Paul, I don't know much about his camera really.
For my own camcorder/DSLR, it worked alot better on high mag and a low power eyepiece, I suppose all cameras are different.

afocal = scope + eyepiece + camera lens + camera body

Why do i suddenly feel like singing aon focal eile?

OK lens is off webcam just by unscrewing it and chip is revealed.

I've attached it to the scope with tape, (crude I know) and it doesn't really show anything, just a blue blur, I'm assuming that as it is a CMOS chip it is not sensitive enough.

Think I'm gonna get another webcam is the below what I need?
www.modernastronomy.com/camerasPlanetary.html

cheers