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MattGrum

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Everything posted by MattGrum

  1. ​MTF charts published by lens producers are already greatly reduced in complexity, in that in general they only show contrast for two spatial frequencies (usually 10 and 40 lp/mm) and two aperture values (usually wide open and f/8) and two image plane orientations (sagital and tangential). The "full" MTF is a four dimensional quantity which is difficult to represent in 2 dimensions. I put "full" in quotes because it also depends on focal length for a zoom lens, and, to an extent, on the focus distance thus it can be a six-dimensional object. I hope you can appreciate why it's impossible to boi
  2. No they really shouldn't. A lens does not "resolve 6MP". A lens renders a certain spatial frequency at a certain contrast ratio. It might take detail at 20 line pairs per millimeter and produce 70% contrast, detail at 50 line pairs per millimeter results in 30% contrast etc. This relationship is captured by the modulation transfer function (MTF), a quantity which varies according to the distance from the image centre, and the direction you measure in (sagital vs tangential). Manufacturers already publish MTF charts for their lenses, which is the equivalent of what you're suggesting, only much
  3. ​ Firstly lenses don't "resolve" a certain number of megapixels, what happens is contrast starts to go down as details get closer together. This is characterised by the MTF of the lens. The sensor has it's own MTF. System resolution is determined by the product of the lens MTF and sensor MTF, thus an improvement in either can lead to an improvement in system resolution. Secondly most EF lenses will provide excellent results with a 50MP sensor over the most important central region of the image, as demonstrated by years of FF lens use on APS-C. I'd bet many would perform adequately even at the
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