Reducing a 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:

Robert: Diagonals are taller than they could be in order to keep eyepieces and barlows from contacting the mirror. With a camera this is not a problem so you could have a machinist shorten the top section of the diagonal. This would be relatively easy if you could find a diagonal that allowed eyepiece adapter to be unscrewed... This is common with 1.25 inch diagonals but no with 2 inchers.

Just a thought.

Jon

Robert,

I have one of the Baader 2" units, and it does have a shorter light path. After measuring it, it is only about 1/2" less, so I
don't know if that will be enough for your needs.

Tom

You ought to be able to assemble a system that
is 1" to 2" shorter than your current setup using
the Baader T-2 mirror diagonal and T-2 plumbing.
The idea would be to eliminate the 2" coupling
between the diagonal mirror and camera, and just
screw the camera directly (more or less) to the
diagonal.

From the scope to camera, it would go something
like this:

2" male - T male tube (2" nose piece, part T2-16)
http://www.alpineastro.com/eyepiece_adapters/eyepiece_adapters.htm#Nosepieces

Baader T-2 mirror diagonal (part T2-1A)
http://www.alpineastro.com/Star_Diagonals/Star_Diagonals.htm#t2%20maxbright

T-2 male-male tube or inverter (part T2-26)
http://www.alpineastro.com/eyepiece_adapters/eyepiece_adapters.htm#Threaded%20Couplings
or
http://www.scopestuff.com/ss_temm.htm

Possibly might want a T locking ring or jam-nut to set rotation (part T2-35)
http://www.alpineastro.com/eyepiece_adapters/eyepiece_adapters.htm#Threaded%20Couplings

T-ring for your camera

Camera

This chart show another way to do it -- note the
SLR camera at the top left.
http://www.alpineastro.com/Reference_Docs/T2-Sys-engl-P.pdf