The Mamiya SX 2.8/105mm is one of two Mamyia SX lenses in the 100mm range, the other one being the SX 2.8/100mm [5/4]. Like the other SX lenses i own, also the SX 2.8/105mm is well made. Focusing is perfectly smooth, the barrel is completely made of metal, and there's a retractable built-in sunshade. The SX 2.8/105mm is a simple [4/4] Ernostar construction.

While its infinity center performance on 24 MP FF is excellent even at f2.8, the borders and even more so the corners suffer quite a bit. At infinity, the lens is nowhere nearly as good as the SX 1.7/85mm or the more common Canon / Minolta / Nikon lenses such as the FD 2.8/100mm, the MD 2.5/100mm or the AiS 2.5/105mm. Even at f5.6 the lens doesnt really shine, and for crisp and sharp corners we have to stop down to f11.

Interestingly, at closer distances (around 2-3 m) the lens has near-perfect corners even at f2.8. It seems that the SX 2.8/105mm has been optimized not for infinity, but for portrait distances.

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