Any used or have one of these Tele-Extenders

[Simon E]

The Deluxe Tele-Extender for Schmidt-Cassegrain telescopes is a hollow tube that allows you to attach a camera to your telescope, with an eyepiece installed.

Been thinking about one of these, so I can use various lens with the DSLR. Anyone had any experience of using one of these?

Si

[mickw]

I think you'll find that's just an adapter so you can fix a camera (still need a T ring) to the back of the scope.
You can also have an eyepiece in the scope as normal, but if you want to bring the camera into operation, you use the "flip mirror" as on the Meade ETX (don't know about others) - this diverts the image from the eyepiece to the camera.

[Simon E]

I have already got a T ring for the Cannon and Nikon, both with a tube like housing attached that go where the eyepiece goes.

This tele extender allows, I believe my camera to attach via a T ring to a wider tube and then over the top of a standard lens eyepiece attached to the telescope. Thus allowing  me to get better magnification and take pictures through say a 10mm/ 40mm/30mm lens already attached to the scope. Celestron want £50.00 for one of these and Meade want £30.00

si

[mickw]

This ?
http://www.telescopehouse.com/acatalog/Meade_Variable_Tele_Extender.html

Lets you fit your camera over a lens eyepiece on the scope - I understand now

[MarkS]

I've used one successfully - it's how I produced my image of the crater Copernicus, my huge mosaic of the moon and a few other images (www.markshelley.co.uk/Astronomy).

There are some caveats to be aware of:
1) You may get severe field curvature - depending on the eyepiece you use.
2) You may get serious chromatic aberration - depending on the eyepiece you use - I found the RGB planes came to focus at different points.
3) As you magnify the image, by say 2x or 3x, the effective F-ratio of the optical train goes up from a basic F10 to say F20 or F30.  At around F30, using a DSLR, you reach the physical limit of optics and pixel spacing - beyond this point you can certainly carry on increasing the magnification but the image simply gets bigger without adding extra resoution in your image.

Another approach would be to use something like a Televue Powermate (essentially a powerful Barlow) instead of eyepiece projection.  But I haven't tried this yet because it is expensive.

Mark

[Daniel]

Hi Simon, I have the Meade tele-extender, i've never got it working correctly, but your welcome to borrow it if you want to try!

Daniel
:O)

[Simon E]

Hi Simon, I have the Meade tele-extender, i've never got it working correctly, but your welcome to borrow it if you want to try!

Daniel
:O)

If I could that would be great, espically before I invested £50.00 on something without trying it. I am hoping to be at the imaging session this Friday.

si