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MD to EOS Adaptor has glass element

Discussion in 'Other Systems' started by bobbywise, Jan 18, 2012.

  1. bobbywise

    bobbywise Mu-43 Regular

    130
    Aug 23, 2011
    Nantes, France
    Hi,

    I'm well into my M43 gear, but since building up a small collection of Minolta Rokkor lenes (bought via this site :smile:) I thought it would be good to also give them a spin on my Canon 550D.

    So from eBay I bought an MD to EOS adaptor (it can be programmed too).
    It arrived today, and I notice that (unlike the M43 adaptors) it has an optical element.

    Does anyone know if the optical element in the MD to EOS adaptor is really needed ? Maybe it's only there to protect the camera body. If it's only there for protection, then I will remove it.

    You thoughts are appreciated :smile:

    Cheers,

    Rob
     
  2. addieleman

    addieleman Mu-43 All-Pro

    Aug 5, 2010
    The Netherlands
    Ad
    The optical element is needed to enable the lens to focus to infinity. It is most probably a weak negative-diopter glass element. Without it the lens would be too far from the sensor and could only be focussed to a certain distance but not farther. The focal length of lens and glass element will also be increased, probably by 10 % or so.

    This optical element will do no good for image quality, but how much it degrades it is hard to say. Testing will reveal that.
     
    • Like Like x 1
  3. shnitz

    shnitz Mu-43 Top Veteran

    989
    Aug 25, 2011
    Austin, TX
    As Ad says, it is necessary because of the register (lens mount to sensor) distance. The factory (hella-expensive) FD-EOS adapter also had a glass element. That is the draw of micro 4/3: with such a short register distance, lenses can be readily adapted through simple metal mounts. Any time you are putting additional glass in your setup, you are degrading the image quality. If the adapter didn't have the glass there, then the adapter would act as an extension tube, since it would move the lens too far away from the sensor:
    Extension tube - Wikipedia, the free encyclopedia
    Flickr: Discussing Anyone use a FD to EOS adapter? in Canon FD