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E-M1X is forgetting the AF Tuning settings.

Discussion in 'Olympus Cameras' started by Mack, Apr 14, 2019.

  1. Mack

    Mack Mu-43 Top Veteran

    Jan 14, 2018
    Ran into a odd issue with the E-M1X CA-F focus today with the 300mm + 1.4 TC.

    Was having some issues with the single small focus point as it seemed to be front focusing as bird feather detail was missing or blurry. Been that way for a couple of days too.

    Decided I'd re-run the Micheal Tapes slant AF tuning chart and its software and I had to resort to a +10 in the setting for the 420mm lens (300mm+TC) which seemed a lot. I put it at the shooting distance of 35 feet too which I was using for the birds.

    I put the 300mm combo on set to +10 for the AF Tuning (CA-F) and it is behaving normally now and feather detail came back. It was warm at 85 degrees F today in the sun, and the body got up to around 120 on the black top and the 300mm lens hood got up to 157 degrees with an IR heat gun. Don't know if the heat of the body or lens is altering the AF Tuning either.

    Found my old PDF lens tests using the Focus Tune (whew!). All my prior lenses were either +1 or -1 for tuning as below:

    Olympus 7-14mm f/2.8 Pro
    At 7mm +1
    At 14mm +1
    Olympus 12-100mm f/4
    At 12mm AF Tune +1
    At 100mm AF Tune -1
    Olympus 45mm f/1.2 Pro -1
    Olympus 75mm f/1.8 -1
    Olympus 300mm f/4 -1
    Olympus 300mm+1.4TC +1

    Must be the heat or distance that is playing with the 300mm and TC to cause it to front focus to where it takes a +10 from the indoor test where it was +1. That or maybe the polarizer is causing the AF shift, but I'd guess it is the heat of the lens outdoors.
    Last edited: Apr 14, 2019
  2. Mack

    Mack Mu-43 Top Veteran

    Jan 14, 2018
    Looking at my AF test charts, it might be the E-M1X has an issue with the Marumi DHG circular polarizer that I was using. Was reading issues with linear polarizers and phase detection AF (C-AF), but not much about circular ones.

    I need to do a same settings test outdoors with and without the Marumi CPL and see if it does indeed shift the AF to +12 from 0 as in the charts attached. Seems a lot of AF shift as it front focuses with it - if this is the issue and not heat or something else.

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  3. AussiePhil

    AussiePhil Mu-43 Hall of Famer Subscribing Member

    Jun 1, 2014
    Canberra, ACT, Aust
    mmmm, certainly looks like the circular polarizer is having an impact, i did experience the same thing with the mk2 and the PL100-400, threw a polarizer on to do some surfing shots and the focus was so far out that it never looked in focus! removed the polarizer and all good, the same polarizer had no visible impact on other lenses though i never measured it.
    • Informative Informative x 1
  4. masayoshi

    masayoshi Mu-43 Top Veteran Subscribing Member

    Dec 5, 2016
    Salt Lake City
    Was your camera under the direct sun when you did the measurement? If so, did you have a chance to re-do the measurement by placing the lens under shade so the lens temperature goes down?
  5. speedy

    speedy Mu-43 All-Pro Subscribing Member

    Nov 27, 2015
    I've had exactly the same experience on my old Canon 550D and 55-250 with a circular polariser. No where near focusing correctly. It was that bad I thought the camera or lens was broken, about to take it back to the store I bought it from, then the thought hit me. Took it off, perfect
    Last edited: Apr 15, 2019 at 2:29 AM
    • Informative Informative x 1
  6. Mack

    Mack Mu-43 Top Veteran

    Jan 14, 2018
    Did the AF Tuning test with and without polarizer in daylight. Kept the camera at 30 feet. I did the same test for both the 300mm f/4 and again with the 1.4x TC attached (420mm).

    With the 300mm, the polarizer did not have much affect on the AF and only pushed it to the +2.

    However, the 420mm using the Olympus MC-14 1.4x TC shifted the AF focus a lot, about 9 points to the plus side verses without it at -1.

    Don't know why the TC is throwing the AF off that much. Seems odd, but given the past few days it does seem to front focus a lot with the polarizer on the 300mm f/4 lens. Might be the stronger magnification with the polarizer if affecting the phase-detection AF more. Be careful with the polarizers and AF.

    The 300mm test without and with polarizer:
    300mm AF Test.jpg
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    The 420mm test without and with polarizer:

    420mm AF Test.jpg
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    • Informative Informative x 1
  7. panamike

    panamike Mu-43 Hall of Famer Subscribing Member

    Jul 5, 2016
    Lincolnshire UK
    I often found with Nikon i needed two tunes one with the converter and one without
    • Informative Informative x 1
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