Apertures on RZ67 lenses

Discussion in 'Medium Format Cameras and Accessories' started by Shootar401, Apr 9, 2013.

  1. Shootar401

    Shootar401 Member

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    Is there a chart that shows what lens apertures perform the best with RZ67 lenses? Just looking for sharpness and minimal diffraction. I have a 65, 110 and 140 so I'm just looking for those numbers, but all of them would be great. I've always shot around ƒ/8 and ƒ/16 and things look good so far.
     
  2. Marc B.

    Marc B. Member

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    I think all three RZ lenses you mentioned are reviewed in the lens test below.
    Look at the lines of resolution in the third column vs the f:stop chosen, (center-middle & edge).

    http://www.hevanet.com/cperez/MF_testing.html
     
  3. polyglot

    polyglot Member

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    About f/8 or f/11 for most lenses. Most are great (especially the M-LA lenses and longer APOs) from f/5.6 but the DOF might be problematic and by f/16 you'll be seeing the beginnings of diffraction.

    While I like that people can measure concrete numbers and always advocate for quantifiable metrics, I don't really think the numbers posted in that link above are correct or at least, they don't match the performance of my lenses. Either I've got strange ones or they've got strange ones, but the sample count is far too small to draw any conclusions. Specifically, the link claims nearly aperture-independent performance from the 110/2.8 whereas in my experience, it is noticeably softer and with more coma at f/2.8, better by f/4 and reaching full sharpness by about f/8. A secondary effect is that performance varies with distance somewhat, and most lenses (except the 140) are not anywhere near flat-field so testing them against a flat target is inherently problematic.
     
    Last edited by a moderator: Apr 9, 2013
  4. Shootar401

    Shootar401 Member

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    Thanks for the responses! My 110 is average, but the 65 MLA is tack sharp, I was never pleased with the 180, so I sold it and bought the 140 which I'm embarrassed to say haven't used yet even though I've had it for 4 months. I usually shoot a few stops down from open, but I'm really looking for a good SHARP wide angle like a 50 (or my 65) that I can use fully stopped down for maximum DOF.
     
  5. polyglot

    polyglot Member

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    There is no RZ67 wideangle sharper than your 65 M-LA; if you want better then you need to save up for a Mamiya 7. The 50 ULD is pretty close or on-par though and is of course wider. Once you reach f/11, they're all (except non-floating wides closer than a couple metres) basically the same in performance; stopping down makes even the poorest lenses look decent. If you stop down to f/22 or lower, it doesn't matter what lens you're using because you will be diffraction-limited and that is a function only of the aperture. Though shooting at f/32 will give you lots of DOF, the results will be visibly soft with any lens.
     
  6. Alan Klein

    Alan Klein Member

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    On landscape pictures where I want front to rear focus as much as possible, I'd opt for stopping down and not worrying about diffraction. I figure that sharper pictures with less DOF is worse than deeper DOF with some diffraction.

    What are others opinions on this issue?
     
  7. polyglot

    polyglot Member

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    Hyperfocus is the optimum tradeoff between DOF and diffraction, assuming you know how much DOF you want.
     
  8. Alan Klein

    Alan Klein Member

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    I estimate the closest object and then check the hyperfocal distance to infinity (or furthest object) and set the focus at hyperfocal distance if infinity is wanted or focus about a third in if furhtest distance is less than infinity. I set the aperture according to the lens I'm using (or from the lens tables) but usually stop down one more stop for good measure.

    That extra stop down might be overdoing it and getting me more into diffraction. What do you think?