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Can't reach focus with Denk II and TV-85.

Started by Adolfojose, 12/15/2005 03:25PM
Posted 12/15/2005 03:25PM Opening Post
I'm requesting your advice.

I own a Universal Denk II Binoviewer, and i am very happy with it. I use it mainly with my 10" F/10 SCT.

However, i am experiencing an unexpected problem.

I have purchased a Tele Vue 85 telescope, wich i use with a WO 2" Dielectric Diagonal for refractors, and, even if i do follow carefully the instructions that came with the Denk for reaching focus with a refractor (either threading the 2" Multi-Purpose OCS into the filter thread of the WO 2" Star Diagonal or on the binoviewer nosepiece), i can't reach focus (the focus is
near, but i can't reach it).

I don't understand what is wrong. I need your advice on what to do.

I'll apreciaste your help.

Adolfo cwy
Posted 12/15/2005 03:31PM #1
You probably need a televue extender to move the eyepiece back. Try lifting up the Denk just a bit to see if you can reach focus.

I had this problem with my TV102 and Denk II after I put a Feathertouch 2.5 inch focuser in...Werner from feathertouch sold me a .75 inch extender and I can now reach focus in all three positions on my 102
Posted 12/15/2005 03:47PM #2
Hi Adolfo,

Sounds like you might be missing a piece for focus in a refractor. The Multi OCS part should be threaded into the binoviewer. There should also be a separate piece that screws into the diagonals filter threads.

The OCS is a focal reducer. It purpose is to bring down the magnification that you get when you screw the other piece into the diagonal. That piece is actually a Barlow element.

Take a close look at the 2" Multi-Purpose OCS. There should be two pieces there. One piece will have a label on it that says 2" Multi-Purpose OCS FMC. If you hold this element up in front of a light bulb in your house the light bulb will look bigger. The other element is probably not labeled. If you hold it up in front of a light bulb, it will make it look smaller.

If you do not have the second element you can use a 2" Barlow in front of the diagonal.

You should get two ranges of power. One with the 2" Multi-Purpose OCS in front of the binoviewer and one without it.

The real trick to reaching focus here is the Barlow element in front of the diagonal.

Don Durbin