Ephotozine Review: Z 100-400/4.5-5.6 S VR

Started Jan 25, 2022 | Discussions thread
anotherMike Forum Pro • Posts: 11,216
Re: Your Findings = Ephotozine Findings

Yea, I'm not negative on E-photozone anymore than the other guys. It's really lenstip and DXO that I have a particularly strong dislike for.

But - let's take a thought exercise here to get back to my point. Say we had a test of the 100-400 at 135 and a test of the Zeiss 135 and it was, just for fun, at F/5.6 and the numbers were the same - or close enough to be the same - at *that* distance, one would be *misled* by the test into thinking the zoom is as good, but if one shot at the longer distance, the zoom wouldn't be. If the test were done at a longer distance (and thus probably not a test chart test), the Zeiss would be better, but then again, would that mislead if you shot in closer ranges... the problem comes in with distance of course.

The other thing is this: assuming you could do my hypothetical across-the-pond chart test, one might find that on an MTF-50 test that the numbers between the two lenses was pretty close, but if you ran an optical bench MTF test, you'd see the Zeiss pull away *at the higher (finer structure) spatial frequencies*, which is where you'll notice the difference.

So sure - the test charts sites are useful in they give a rudimentary/rough indicator of things in the close range, but they don't tell enough of the tale.

Really nobody will ever do so - too expensive (as Roger Cicala has noted before), because I would like to see:

  • Optical Bench MTF at closer range, wide open and three stops down
    • Along with through-focus MTF at that range at wide open and 3 stops down
  • Optical Bench MTF at infinity, wide open and three stops down
  • Field Curvature graph at infinity at 30 (perhaps 40) lp/mm
    • A note for KenW if he's reading this far: The problem with field curvature is that it's NOT always a consistent shape - there are quite a few lenses that score highly that have wave or oddball shape FC and dead zones galore, due to astigmatism issues, but whose properties include the "edge" and "corner" of that inconsistent shape of curvature aligning well to a typical flat chart test edge and corner locations. Which is why I like Rogers FC graphs - easy to see the problems (and the astigmatism)

And I'd want to see the MTF presented both in "lens designer view" (contrast vs frequency) and "photographers view" (contrast against field position, different traces for core frequencies)

In my dream world, there is no need, nor desire, for MTF50 chart testing at all.

No way anyone is doing that for free....

But that would tell us *so much* more, including things that now are only discussed subjectively.

So I dream of the powerball

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