[Poita (Peter)]

I was having trouble focusing my PST for photography, and decided that the prism focus assembly in 'the black box' was the main culprit.
I unscrewed the Etalon from the black box and removed the blocking filter/eyepiece holder from the back of the black box.

I took the GSO SCT crayford focuser, and found that the threads were pretty close to the threads on the PST etalon, not exact, but close enough.

I threaded the etalon onto the SCT crayford, and used some adapters to put the blocking filter and eyepiece holder at the other end of the crayford focuser. I ended up having to add about 40mm of 1.25" tube extensions to the eyepiece end of the crayford.

The difference was astounding, razor sharp images compared to the stock PST when looking through the eyepiece, and it was *much* easier to focus for the CCD camera with the 10:1 crayford.

The only problem is you need to use tube rings or a clamshell to mount the PST onto the tripod. I solved the problem temporarily by feeding the PST tube into the finder-scope rings on my 105mm refractor to do the testing, but a more solid solution will be required!

But for a 1/2 hour's work, it was the best DIY mod I have ever done. The views are considerably better and the focusing is much more refined.