Comparing sharpness of 16-80 to other lenses

Started 9 months ago | Discussions thread
Belgarchi Senior Member • Posts: 2,014
Re: Comparing sharpness of 16-80 to other lenses
1

decaf14 wrote:

Steve Bingham wrote:

The problem with these MTF files is that they are:

1- Theoretical - just theoretical guesstimates.

2- Taken with the lens wide open.

3- Produced by Fuji

4- Nobody uses 15 lines/mm

They really can't be used for comparisons. However, I applaud your effort.

1. Theory and practice are closely intertwined. These lenses are designed first in theory, then implemented in practice. Although there are most definitely discrepancies with the actual product and the simulated results, I would argue that the actual end result is a left-skewed distribution with theoretical perfection being achieved by 0% of people, but most people achieving near 85% perfection. The right side of the graph is maximum performance and the left side is a trashed lens.

2. Yes, they were taken wide open. Why is this is a problem? I agree there could be more information, but these tests are testing the lens at "full throttle" if you will. The extremes of its performance. I think maybe you mean that the problem is that there is not testing at different apertures. i.e. not 'enough' testing.

3. Why is this an issue? Produced by the optical experts... tested by optical experts... using professional simulation software that uses ray tracing algorithms to predict the path of every photon that passes through the lens. It's more than consumers can do.

4. See right graph of each image, labelled 45 lw/mm.

I think you are mostly pointing out limitations of the comparison and not problems with it. The most valid limitation is the fact that the simulated product is not the real one. Your first point. However, simulation is generally close to theory.

I would like to hear more on why you perceive this comparison as a write-off. I think it holds some value, but I am the one who wrote it so there's a little bias there :).

For what distance are these MTF curves?

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