Canon adapter to use telephoto lens as telescope

I want to thank forum members' help in answering questions I've had since I've

gotten back into the Canon FD system. You people are great! Now, I'm curious

about an accessory that Canon made that allowed the use of a long lens as a

spotting or telescope. Does anybody have a picture of this item? Does it show

a right-side-up, unreversed view? What magnification does it produce - is it

something like 30x magnification when used with a 300mm lens? I've heard that

it is mounted at a right angle to the lens axis - does this make it more or

less convenient and comfortable to use? The only similar product that I've

ever seen was a straight-through (not at right angle) tube that was on a Pentax

(?), or Nikon(?), many years ago.

Canon never made one of these. And I've never seen one that was a right angle attachment.

 

The only right angle attachments that Canon has made is designed to fit on the viewfinder of a camera body. Unless you go back to the Rangefinder Mirror boxes which could have been used as a telescope adapter on a LTM mount lens. But sucked at it due to the use of the mirror and loss of light. And this would not fit any later lens like ours.

 

BUT Vivitar sold a straight through design one Tokina made one and I believe at least a couple others also sold them. They are what a telescope guy would refer to as a 4X eye piece.

 

SO if you have a 500mm lens which when used for 35mm is said to be a 10 power lens (50mm std. lens x 10 = 500mm) if you put the telescope eyepiece on the back of the lens you end up with a 40X telescope.

 

I use one on my Sigma 600mm f8.0 Mirror as a spotting scope for shooting and birdwatching.

 

Mine is a Vivitar sold version and works amazingly well. I have a Meade ETX-90 UHTC telescope and my 500mm f4.5L S.S.C. with the eye piece holds up amazingly well at the same power.

 

OH yes it is a right side up correct right to left view.

Mark, you're right. I asked the prospective seller of such a device, and he is either uninformed or intentionally misleading.

Actually, I'm holding one of these right now. It converts a 500mm into a 1500mm, and goes directly onto the rear lens mount like a camera. Mine says "Made In Japan For CANON TELESCOPE ADAPTER." It's got a simple inbuilt diopter adjustment ring, and a slightly ripped rubber eyecup. All I've got is my mobile phone camera, but I can post some high-quality pics soon if someone wants. I think it's a pretty cool little thing, but not that practical.