Help judging performance of my FE55z, FE35f2.8z horizon/infinity

Started Jul 5, 2016 | Questions thread
JimKasson
JimKasson Forum Pro • Posts: 26,549
Re: Different testing rigor for "good copy vs bad" compared to getting valid MtfMapper numbers?

l_d_allan wrote:

JimKasson wrote:

I would like to add flat target the above list. Folded and then straightened newspaper taped to a wall from two corners is not quite there. And alignment.

You are absolutely correct. I have found from experience that just dry mounting a target to a piece of foam core won't do it.

I'm wondering if you would make a distinction between a "level of attention to detail" that is adequate for "good copy vs bad copy testing", vs a higher level for getting valid, repeatable MtfMapper numbers within +/- 10 lp/ph

Plus or minus ten? With lenses like the Otus 85, I barely get +/- 50 even with a focusing rail and a razor blade! Lesser lenses aren't such a problem.

Am I incorrect to think that:

If I were going to do brick wall testing, I'd print up five ISO 12233 charts, and attach them to the wall so that one is in the center and the other four are at the corners. Then, if I didn't want to do slanted edge testing, I'd read the extinction resolution off the rosettes.

I presented a version of this test that doesn't require precise alignment on my blog, but I now believe the OOF LED is a superior test and much less likely to produce false positives.

  • ...
  • that a typical DPR member can get valid captures
  • from which to evaluate whether they have a "good copy" or not.

I dunno. From what I see posted in the forum, I despair of achieving all that.

Or, is a simpler de-centering test mostly or fully adequate for "good copy vs bad copy"?

My belief is that it is, but I don't' know that for a fact, as I don't have any lenses that measure as materially decentered, so I don't know how sensitive the test is.

Prof. Hank has such lenses, and has tried the OOF LED test with them, and says that it works. I tend to take Prof. Hank's word on things like this. I respect him a lot.

Jim

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