Test results: Canon FD lenses on LifePixel IR converted NEX-7

Discussion in 'Adapted Lenses' started by roundball, Jun 22, 2016.

  1. roundball

    roundball TalkEmount Legend

    Oct 8, 2013
    In the process of testing various lenses I've learned something unexpected along the way…may not be new news to anyone here, but I’ll share it anyway in case.

    First, the following Canon FD lenses I’ve tested are excellent on the Infrared NEX-7.
    24/2.8 prime, 24-35/3.5-L zoom, 28-85/4.0 zoom, 35-105/3.5 zoom
    Meaning they are sharp and have no ‘hot spots’…testing them at short, medium, and long range zoom settings, and at wide open, middle, and stopped down apertures at each of those zoom settings. I also tested with and without their Skylight filters installed.
    ( not wanting to start tangential discussions...simply incorporate filter tests as I’ve always been in the camp of liking some degree of lens protection by a filter ).

    I also have Canon FDn 17/4.0 UWA and 20/2.8 SWA lenses...and here’s where it got interesting. In each case when I got to F22, I could see a faint 'hot spot' dead center…and that was with the bright sun behind me…only shooting into the bright Oat field / treeline out in front of me.

    I’ve read that ‘Hot Spots’ can be caused by light reflections off of lens barrel walls, or between internal lens elements, or between internal lens elements and the sensor, etc. Since I couldn’t do anything about those kinds of possibilities…I wondered if a reflection might be occurring between the pronounced curves of the wide angle front elements and the filter glass that was only a few thousandths of an inch of front of the lens curve. So I removed the filters and reran the tests…must be living under a star because the F22 Hot Spots disappeared.

    As an aside, I also learned got first hand experience using the ‘Infrared markings’ (in red) on the Canon lenses, showing where Infinity focus is in the Infrared world…works like a charm. So the few daily trips to the nearby “OFLTS” (Oat Field Landscape Testing Studio) :)  have been very worthwhile.
    • Informative Informative x 3
  2. addieleman

    addieleman Passionate amateur Subscribing Member

    Nov 13, 2012
    Ad Dieleman
  3. roundball

    roundball TalkEmount Legend

    Oct 8, 2013
    Just FWIW, tested a Canon FDn 50-135/3.5 zoom on the IR / NEX-7 today.
    Worked perfectly at all zoom ranges, all apertures, with & without a Skylight filter.
  4. sam

    sam TalkEmount Regular

    Nov 23, 2015
    Thanks for this.
    Just stsrted playing with IR on the NEX 5R. My FD24 without the UV filter, had better results. I forgot about the IR markings. Will have to play some more.
    Also have FD135 AND FL50 to try out.
    • Like Like x 1
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