More on the new lens

2 thoughts on “More on the new lens”

  1. The magnification factor does come into play and there is no way to avoid it. The reason your 18-200 has a smaller image at the 200 point is because that 18-200 does not really go to 200! Zoom lenses tend to be a little optimistic at both ends and are allowed leeway in their labeling. An 18-200 is likely to be a little longer at the wide end and a little shorter at the long end — but when competing with Nikon’s 18-200, a 20-180 might not be as competitive. Also, the fstop may not be exactly a 3.5 to 6.3 but an f/4 to f/8 — but since we are taking readings thru the lens and not a separate meter we can’t tell but if you used a separe meter you could — and it isnt just Sigma playing this game — they all do it. For many years, the Leica 50mm Summicron was actually a 52mm. Also, the Nikon factor is actually 1.52x and Canon has two factors on different models: 1.6x and 1.3x. T

  2. David, Thanks for the clarifications. Even so, I’m curious to see how this lens behaves with my 35mm SLR, given the barreling effect.

    Are you saying that Nikon’s 18-200 is a true 18-200, or is it optimistic at both ends, too?

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