I used the scope with a 1991-vintage Tele Vue Paracorr, which increases the scope's effective focal length
by 15% but also fills the 1.
It works purely as a field flattener and does not change the effective focal length
or focal ratio of your telescope.
SPECIFICATIONS & MEASUREMENTS * TMB-92 Signature Series Refractor Clear aperture 92 mm Effective focal length
505 mm Focal ratio f/5.
To increase the size of the object on the imaging sensor, we need to increase the effective focal length
of our telescope, at the cost of a slower focal ratio.
WHAT WE LIKE: Compact and lightweight Superbly flat fields with reducer lenses Versatile photo-visual system WHAT WE DON'T LIKE: Slight chromatic aberration apparent visually Light falloff at image corners Complex and confusing stacks of adapter rings SPECIFICATIONS & MEASUREMENTS * BORG 77EDII Clear aperture 76 mm Effective focal length
331 mm Focal ratio f/4.
At roughly 10,000 mm effective focal length
(200x), stars remained virtually stationary as I racked the focus in and out--a very impressive feat for such high magnification, and there was no discernable backlash.