What is a lens wafer?

Discussion in 'Adapted Lenses' started by Klorenzo, Apr 28, 2014.

  1. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    Hi, I took a few pictures with a Nikon 50mm 1.4, this one I think:

    http://www.destoutz.ch/lens_50mm_f1.4_2999999.html

    The "problem" is that wide open has very little contrast, at f/2 there is a big jump and another one at 2.8. I did a quick google search and I found this:

    http://www.dpreview.com/forums/thread/3447222

    Exactly the same. In this thread I found this sentence:

    "Like most of the older lenses on a quarter of a sensor, you have way too much light in the chamber that is bouncing around without any real benefit to it. What you need to do is put the wafer on the back of the lens to cut this light of."

    Well, what is the wafer? I couldn't find much on google.
     
  2. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    Baffle.
    A black card with an oblong hole cut in it.
    Calling it "wafer" is pretty stupid in my opinion, ignore their terms. Using a biscuit or an after-eight mint would be asking for trouble.
    All the lens modifiers call these things "baffles". (or "stop", meh)
    You need to experiment with a series of circular black cards with different sizes of 4:3 oblongs cut out.
    You want the keep the one which improves contrast the most without reducing the effective aperture too much : which shows up in the shutterspeed chosen by your camera in "A" mode or "P" mode.
    Testing right is the key.
    Have a nice play ... there is also some stuff called "flock" ...
     
    • Like Like x 1
  3. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    Thanks, now I got a lot of results, too many maybe :)

    It looks fun, I'm going to try.

    I have this article as a starting point: http://www.street-photo.fr/fr/materiel/27/35

    With this extra indication: "To work best the baffle should be at the focal plane, which is exactly the distance in mm from the sensor as the focal length at which you are shooting."

    And I also found this, in the same thread: "The front filter with reverse grad effect or simply a very deep hood ( again cutting peripheral rays ) is much more practical". It sounds I should be able to get the same result with just a deep hood or a special filter. Is this correct?

    I used the standard hood for the lens but I can see no difference. Maybe I should try a deeper one?
     
  4. RnR

    RnR Mu-43 All-Pro

    Sep 25, 2011
    Brisbane, Australia
    Hasse
    • Like Like x 1
  5. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    No, that's not correct, ( and with a deeper hood you'll be risking vignetting ... but bigger hoods are always better than littler hoods if they are the right angle.)
    And ... forget the bit about focal plane.
    Experiment with various big round holes near the lens, and more oblong holes nearer the sensor. Be careful. Stick 'em on the adapter ring, front or back if you can.
    You will end up with something which improves contrast (and perceived sharpness) without blocking too much 'good' light.

    I fitted a round-holed baffle into my Konica-Hexanon 50mm and it improved wide-open contrast and was still brighter than the next real aperture stop down. worth it, but only on some lenses.