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Category Archives: Resolution Tests

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 [...]

A Quick Look at the New Sigma 24-35 f/2 Art

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Image Courtesy Sigma USA   I generally do MTF testing on multiple copies of a given lens so that I can present the averages, look at sample variation, and stuff like that. I'm always aware that looking at any single copy of a lens, especially a zoom lens, gives only a limited prediction of how [...]

24-70 f/2.8 Zoom MTF and Variation

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We've finished, mostly, our fairly long series of articles on SLR prime lens variation. We started with prime lenses for several reasons. They are much quicker (and quicker is a relative term here) to test than zooms. They are simpler lenses and we expected that meant they would have less variation. We learned a lot [...]

Variation Measurements for Telephoto Lenses

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We're nearing the end of the Varation series for prime lenses. If you are joining in late, you may want to go back to the original article for an introduction into the methods used. Today will look at the short telephoto group, lenses ranging in focal length from 85mm to 150mm. We've also included a summary table of [...]

Variation Measurements for Wide-Angle Lenses

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When we started this series, we introduced our methods using 24mm lenses, then followed up with looks at the 50mm and 35mm groups. Today we're going to go back to the wide-angle lenses; the ones we expect to have the most variation of all. We probably should call this post the Zeiss Invitational, since they [...]

Variance Measurement for 35mm SLR Lenses

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Last week we posted optical bench MTF and copy-to-copy variation measurements for 50mm SLR lenses. We're going to continue that series this week with the same measurements for the 35mm lenses. This set should fill out the wide-to-standard range lenses and gives us a lot of interesting data as we continue to look at what factors [...]