connecting camera and eyepiece at the same time

[mindburner]

Had a short while last night to get the 300p GOTO dob out. I got m31 lined up in the 26mm EP the switched to 10, all's good image still there. I attached my video camera and by the time I refocus/adjust the camera, andromeda is way. This was very frustrating I must say. Par for the course with dobs but I started thinking there must be some way to view both at the same time. These ideas show off my ignorance of optics i'msure but here goes..

*Binoviewer - with lens in one and cam in the other port?

*Off axis - don't know much about this

*flip mirror - apparently there may be focus issues with this approach.

A new mount/scope & guidescope is the answer,but until I can get what I need I was hoping to persevere with the dob as the visual images are so good.

Any ideas or advice very much appreciated as I just don't want to start spending more money if it's not likely to work out

thanks

[todd8137]

hi there not sure what you try in to do ,but not sure if you would get m31 on the chip of a web cam you should try the moon out first or a planet,can you not stick the web cam in and use the finder scope? to line up with i have had small success`s with a few bright dso`s but my 300p is not goto and am not sure how well that would track but the moon and planets with a webcam works a treat.

i also have a cannon 10d un modded and have taken a few deep space objects but with no motors on my dob a waste of time

havwe you tried to piggy back the nikon on the goto 90mm you have i do this a lot for wide field shots i can get 45 secs with out trails and 10 of those with a few dark frames works well

cheers pat

[cantab]

Using a binoviewer to split between an EP and a camera would be an innovative idea, and with suitable modifications (you will need independent focus on each side of the binoviewer) could work well, although with each getting only half the light it won't be good for the faintest detail.

But since you have a GOTO, can you not just set it to track, so it'll hold your target in the view while you're swapping around EPs and cameras?

[RobH]

A flip mirror is the normal way to resolve this issue, but unfortunately you'll need more back focus than your dob is likely to give, and the same goes for binoviewers.

There are some very thin off axis guidders available (the Teleskop Service one comes to mind), but these are really only of use for imaging where you have a few stars visible as they will show you the very edge of the field of view, not the centre, and they aren't cheap either.

Sorry to not be of more help.

Rob

[Tinker1947]

One of these things...???

First Light Optics - Vixen Flip Mirror

[Cornelius Varley]

Make the 10mm eyepiece parfocal using a parfocalising ring Accessories @ Modern Astronomy

Peter

[Cloengaa]

Normally when you stick the Phillips SPC900 webcam in the focuser the webcam is actually acting as a 6mm eyepiece. So maybe the 10mm makes your view centre but at 6 mm it is not.

I would try and get a 6mm eyepiece and centre it there and then switch to webcam.

[mindburner]

Using a binoviewer to split between an EP and a camera would be an innovative idea, and with suitable modifications (you will need independent focus on each side of the binoviewer) could work well, although with each getting only half the light it won't be good for the faintest detail.

But since you have a GOTO, can you not just set it to track, so it'll hold your target in the view while you're swapping around EPs and cameras?

hi thanks for the info. I should have maybe said the camera is a SCB-4000 CCTV camera for live video of DSO's etc. It's the sheer weight of the thing with wires et all makes for a very easy way to move a big dob out of alignment,. The dob is tracking but they are a bit wobbly even with that and feather touch does it. I would like to eliminate the swapping out alltogether if possible.

[Merlin66]

Yes,

The Vixen is OK but needs about 80mm of back focus...check out the available space before spending $$$