You can double the power of TeleVue Panoptic eyepieces by adding the 2” 2x Big Barlow. For optimum performance, however, the Panoptic Interface Lens is highly recommended to pull the eyepiece exit pupil back to the ideal eyepoint to prevent vignetting of the image, while optimizing the eyepiece’s edge correction to the levels found in TeleVue Nagler eyepieces.
TeleVue considers this interface lens essential when using the 2” Big Barlow with the 35mm and 27mm Panoptics, helpful with the 22mm, and unnecessary with the 15mm. It is unneeded with any other eyepiece/Big Barlow combination.
It has multi-coatings, blackened lens edges, and an undercut in the barrel for extra locking security.
My Panoptic Interface has been used just a few times. Finish is in excellent condition. Light set screw marks on barrel.
$50 + shipping. PayPal preferred.