A shorter diagonal?

Hi ladies and gents,

Preparing to photograph an eclipse at sea, I am trying several combinations of telescopes and cameras. I have a lovely fast refractor that I would like to use for wide field imaging, but the camera only comes into focus if used straight thru with an extender; a 2 inch diagonal is too long by a very slight amount.

For the sake of stability I will have the mount as low as I can; focusing straight through will be difficult even with a solar filter, as I will likely be dazzled by a chance glance of sunlight. Is there any way to shorten the light path of a 2 inch star diagonal? Does anyone sell a shorter 2 inch diagonal?

Cheers

Robert Howe

Attached Image:

How about a shorter focuser? Also, I am not sure it can be adapted, but I thought the dedicated FSQ diagonal was a very short optical path.

Good luck
Kevin

A question rather than answer-- Do prism diagonals sometimes have shorter optical paths than mirror diagonals, because of the refractive effect of the glass? Thought I read that somewhere, but maybe incorrect, or perhaps not significant enough effect to give you your few millimeters. Someone here likely knows.

Robert Howe said:

Hi ladies and gents,

Preparing to photograph an eclipse at sea, I am trying several combinations of telescopes and cameras. I have a lovely fast refractor that I would like to use for wide field imaging, but the camera only comes into focus if used straight thru with an extender; a 2 inch diagonal is too long by a very slight amount.

For the sake of stability I will have the mount as low as I can; focusing straight through will be difficult even with a solar filter, as I will likely be dazzled by a chance glance of sunlight. Is there any way to shorten the light path of a 2 inch star diagonal? Does anyone sell a shorter 2 inch diagonal?

Cheers

Robert Howe

Hi Robert:

Baader's T-2 diagonal is very short and there are tons of camera connection options. The prism version of this diagnal comes with Baader Mark V binoviewers specifically for its short path length. There is also a mirror version. The T-2 prism has less than 2" sized aperture though, and I suppose it might vignette, depending on your camera.

http://www.buytelescopes.com/product.aspx?p_id=5738&store_id=&did=#

Jim