Category Archives: Lenses and Optics

Sigma 24-35mm f/2 DG HSM Art MTF Curves and Sample Variation

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For years now, I've been telling people to always take the results of tests done on one copy of a lens with a serious grain of salt. Not matter how carefully it was tested, it's still just one copy. Others will be worse. Others will be better. Because I'm so aware of copy variation, I [...]

Cine Lens Teardown Comparison: Zeiss 85mm CP.2 T2.1 and Rokinon Xeen 85mm T1.5

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I was pretty excited when I first heard about the Rokinon Xeen line of Cinema lenses. For several years now, Samyang / Rokinon photography lenses have given photographers with reasonable expectations some superb alternatives. They sell optically excellent lenses at amazingly low prices. There are compromises made to accomplish this goal, of course, but they [...]

MTF and Variation: An Example

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We've spent most of the last month establishing a database of MTF curves and expected copy-to-copy variation for a number of lenses. Most people have a general idea about what we're doing, can follow along the basics of MTF curves, etc. But many other people also have a very good question, "How much of a [...]

Wide-Angle Zoom MTF and Variations

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We recently published the MTF and variation curves of standard range lenses and now are going to tackle wide-angle zooms. As we've seen, zooms have more variation than primes and wide-angle primes have more variation than standard range primes. Also, the MTF curves of wide-angle primes are weaker off-axis than standard range primes. So my [...]

Quick MTF of the Tokina 24-70 f/2.8 PRO Fx

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Courtesy Tokina, USA Tokina is releasing a new competitor in the 24-70mm f/2.8 standard zoom lens group. It's a reasonably sized lens, having an 82mm diameter front ring, measuring 4.25 inches long, and weighing 2.2 pounds. That's just a bit smaller and lighter than the Tamron 24-70mm f/2.8 VC USD or Canon 24-70mm f/2.8 Mk [...]