140mm!!!! Ye gads! You'll be able to crawl right into those proms Michael.
Actually I have a Baader Cool-ERF, a cell for the Megrez 90 and the PST etalon to 2 inch adaptor. It's a good match for the Megrez 90 as the light cone converges to 20mm in the focussing range, so there are no issues with backfocus.
One major problem though. I had my PST "repaired" in Germany to fix the "rust problem". They replaced it with a new style PST on which the eyepiece spacer cannot be removed. Cacn you believe that? They are actively preventing people from making this mod now :evil: . So I have all the equipment and am seriously considering cutting the spacer tube off altogether. Would never be able to sell the PST if I upgrade then however.
BTW I saw a post from Arthur of Ambermille mentioning that he thought the PST etalon could be compromised at greater than 90mm. But I have seen some images from a larger setup by Cai Uso. Could be that his setup was purely for imaging though.
Trev
  