Neil Heacock's Blog – June 2011 Archive (1)

A Direct Comparison Of 200mm f/4 and a 90mm f/7 Scopes

I've had a few conversations recently about the difference between my Vixen R200SS and my Vixen ED103S.

The R200SS

Aperture: 200mm (8")

F Ratio: f/4

Design: Newtonian

The ED103S

Aperture: 103mm (masked down to 90mm due to spacers in the light path causing unwanted diffraction spikes)

F Ratio: f/7.7 (but f/8.8 after the masking and f/7 after introducing the reducer)

Design: Apochromatic… Continue

Added by Neil Heacock on June 1, 2011 at 1:00pm — 11 Comments