Barlow Question??

Gentlemen, is it necessary to employ an interface when using a 2X Barlow with a 35mm. Pan. ( Tele Vue I hear recommends one ) appreciate any thoughts/experiences with these .. John M

The Panoptic-Barlow interface, in essence, is one half of a Powermate (Big Barlow + P-B interface = 2X Powermate). While not strictly necessary for use with the Panoptic, the P-B interface -- like the Powermates it preceded -- offers pupil correction, maintains inherent eye relief, and prevents vignetting.

It also adds a fair chunk to a given ocular "stack."

While I have no personal experience with the P-B interface and cannot speak to its potential "necessity," I hope the above info helps a little.

Best wishes.
-Dan