All About Photographic Lenses.
Specifications, comparison, reviews, MTF-charts for lenses by Canon, Nikon, Sony, Pentax, Olympus, Sigma, Tamron, Carl Zeiss, etc.

Sigma Mirror 600 mm f/ 8 used:

NameFull namePlaceScoresRank
1mjogar 24.5lvl.1 (Lens-Learner)
2Bill Gibbs 46.4lvl.1 (Lens-Learner)