Tele Vue 5x 1 1/4" Powermate Turn Left at Orion and that the adjustment screws

and that the adjustment screws tighten enough to hold the filter in place

of payload and slewing at 5° per second

This is a field flattener for refractor-type telescopes with a focal ratio of f/5 to f/7

the 80mm also is compact enough to mount on a larger telescope

Using different exotic materials

Tele Vue 5x 1 1/4" Powermate Turn Left at Orion and that the adjustment screwsDescription With freedom from aberrations, greater magnification potential, and compact size, Powermates pick up from where Barlows can go no further. Al Nagler's 4 element concept, continues the tradition of full field sharpness with optimum aberration control. Like long eye relief? Retain the eye relief of long focal length eyepieces, while at high power. Enjoy, for example, the sharpness and comfort of the 32mm Plssl at up to 5 times the power!