Paracorr and Pentax XW EP's

(posted in Eyepieces section too - I thought I'd post here as well to see if I get some responses...)

What height setting on the Paracorr's tunable top would folks suggest for a 12.5" f/5 scope? I know where I've used it in the past for Radians - are the Pentax XWs different in this regard? Maybe wider FOV = higher Paracorr top setting?

Thanks!

Doug,
Reading from the Tele Vue web site, "As you've read, all Newtonian/Dobsonian telescopes can benefit from using a Tele Vue Paracorr (Parabola Corrector) to eliminate coma in the image. One aspect to optimizing this correction is the distance of the eyepieces focus point (field stop location) to the last surface of the Paracorr lens (within a small +/- tolerance of course). Typical eyepieces used with fast Newtonians can have field stop locations differing by as much as half an inch. To accommodate for the differences, we developed the "Tunable Top." Maybe a call to Tele Vue to find out what this distance is would be the best solution to your question. Please share it with us if your do.
Stu