50mm Prime with Resolution for a D800? Come on Nikon/Sigma!

Started 7 months ago | Questions thread
Scott McMorrow
Regular MemberPosts: 354
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Re: 50mm Prime with Resolution for a D800? Come on Nikon/Sigma!
In reply to MisterHairy, 7 months ago

MisterHairy

How are you measuring resolution? Do you mean MTF50, MFT30, ,MTF10, or some other measurement criteria? I'm quite aware of Nyquist and aliasing. I deal with it all the time in my day job modeling, simulating, and designing ultra high bandwidth digital communication interconnect.

You've not yet defined what you mean. Low contrast image energy beyond Nyquist can cause aliasing, which due to it's repetitive nature sticks out like a sore thumb. Moire is very sensitive to even minute amounts of image contrast. Just because there is enough image contrast to cause moire does not mean that it's very useful contrast. Which is why measurements such as MTF50 are used for meaningful resolution comparisons.

If you tell me that a particular lens on the D800 out resolves the sensor using an MTF10 measurement, I'd absolutely agree with you. MTF30, then I'd start asking how the measurement was made, and how the image was sharpened. MTF50, except for a few lenses I would call BS. I"ve made measurements on a few of my lenses with Imatest, and have correlated the results to Roger Cicala's unsharpened RAW measurements. I've then looked at the MTF50 results with Imatest's optimal sharpening filter and with a sweep of different sharpening parameters using Lightroom. None of these results approaches the theoretical resolution of the D800 sensor when measured at MTF50, and definitely not when looked at from corner to corner, with center image focus.

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