27 pan question

Hi everybody--
on the televue website the 27 pan is listed as parfocal group "A", while the type 6 naglers and 16 type 5 are in parfocal group "B"--so can anyone tell me how much focus travel there is between these two, specifically, between the 27 pan and either the 16 type 5 or the 11 type 6? Thanks,
George
(considering a helical with limited travel)

This will depend on your 1.25" adapter. The "F" column in the table gives 0.29" for the Panoptic 27, while all the Parfocal B eyepieces have an "F" value of 0.25" . So if both eyepieces were 2", we'd say that you'd need 0.29 - 0.25 = 0.04" of focus travel when going from the Panoptic 27 to a Parfocal B eyepiece. That's OUT travel when going from Parfocal B to the Panoptic 27 and IN travel when going from the Panoptic 27 to the Parfocal B point. Let's say for the sake of argument that your 1.25" adapter adds 0.4" of height. Then your Parfocal B eyepieces will actually have a new "F" value of 0.25 - 0.4 = -0.15". Now going from the Panoptic 27 to the Parfocal B eyepieces will require 0.29 - (-0.15") = 0.44" of focus travel. That's IN travel when going from the Pan to the Parfocal B, OUT travel going the other way.