bernard_L
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- Feb 17, 2008
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You would be better off basing your decision on actual data. 6400ppi is just vaporware. Given enough memory, I could even resample these images to, say, 25600 ppi.The software tells me I'm getting 6400 ppi, which comes to about but I've seen many conflicting reports on what the actual optical resolution of the V850 might be.
Here is actual data from my V700, which is not radically different from the V850 (cold cathode source versus LED). These are MTF charts. Obtained by running the V700 (via vuescan) at 1600 ppi nominal, with near-optimum height adjustment. Using the slanted edge method, but that does not matter.
So, at 1600 ppi, the contrast (modulation factor) is down to 30% at 0.2 cycle/pixel. Corresponding to 0.2x2x1600=640ppi. Someone disagrees about the derivation of 640 ppi, feel free; I have seen this kind of forum discussion before and no thank you.
With properly taylored usm restoration, the mtf can be boosted where the response is non-zero, giving this:
So, being a little optimistic, one might say that the response goes out to 0.4 cycle/pixel, resulting in 0.4x2x1600=1280ppi. My guesstimate of 1600ppi in post 13 above was actually generous to the V700/850. So from a 11x17mm negative, you can get 0.47Mpx.