On Mon, Jul 22, 2002 at 03:22:19PM -0700, William Sommerwerck wrote:
> MTF is to lenses what frequency response is to amplifiers. The MTF rating is
> the spatial frequency at which the lens's contrast drops to 50%.
Ah, spatal frequency was the word I missed in my dictionary :-)
>
> The "catch" with MTF is that is a single frequency. It doesn't tell us how
> the lens behaves at higher and lower frequencies.
I think this is one way to use MTF values. I scanned the diagrams
cause they do tell a bit more ;-).
Who does use the 50 riteria?
Well I think 50 0s a very hard criteria. depending on
image presentation somewhere between 20..30 ontrast is
the limit necessary for human eye to recognize fine structures.
Sure film influence and image processing should also be considered.
Frieder Faig
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