Founder Optics 1.25" Dielectric Diagonal Mirror - DIA1.25-M Adjustable Dew Shields The optical design is air-spaced

The optical design is air-spaced and produces a 44mm image circle so you can use larger full frame sensors without vignetting

Optical Design Refractor Aperture 80mm (3

7 Optics Type: Focal Reducer Lens Aperture: 43 mm Focal Length: -NA- Optical Design: 4-Elements FL Reduction: 0

With magnification from 40 to 400x (1600x with digital zoom)

Founder Optics 1.25" Dielectric Diagonal Mirror - DIA1.25-M Adjustable Dew Shields The optical design is air-spacedIf you're looking for a nice 1. 25" diagonal for your refractor, this model from Founder Optics will do the trick. The compression ring twists to lock in 1. 25" barreled accessories without marring and fiddling with small screws in the dark. The telescope side slides into 1. 25" focusers. This Founder Optics 90 degree mirror diagonal has a dielectric coating with over 99. 99% reflectivity for bright images.