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Focus problem with EM5 II - ideas?

Discussion in 'Olympus Cameras' started by Tapper, Mar 10, 2015.

  1. Tapper

    Tapper Mu-43 Regular

    184
    Mar 12, 2013
    Hey everyone,

    I noticed some "back focused" shots I took of food, so I did some tests tonight. In general my EM5 II with 12-40 f2.8 does very well, but for some reason in some situations it misses focus badly.

    Here is an example. I shot the same scene (a brownie with some pecan pieces sticking out) multiple times on a tripod at various ISO's. I shot the same with my RX100M3 for comparison. On both cameras I used the small focus point, and the focus was set to the middle pecan piece.

    The EM5 II got the colors MUCH better than the RX100M3, but the little Sony got the focus right. As you can see, the middle pecan piece is blurry on the EM5 II and the 2 pieces further back are in focus. Please note it wasn't just one shot -- I took a series of 4 shots on both cameras, and the EM5 II did the same "back focusing" in each exposure while the RX100M3 correctly focused.

    What causes this to happen?

    Please also note, it doesn't always back focus like that. I did an extensive series of tests and in most cases it focused well. But every now and then with some subjects it does that.

    Focus_Test.
     
    Last edited: Mar 10, 2015
  2. Joon525

    Joon525 Mu-43 Regular

    119
    Sep 24, 2012
    NJ
    Did you remember to turn the IBIS OFF since it was on a tripod?
     
  3. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    Maybe the E-m5ii doesn't like walnuts?

    Seriously - AF is complex. It seems here that it's used a wider area than the focus box itself. I think you just need to learn how it works and adapt accordingly.
     
  4. Jorin

    Jorin New to Mu-43

    9
    Mar 6, 2015
    Jorin arriola
    Sorry I'm a little new. You want the IBIS off when it's on a tripod?
     
  5. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    I think the later cameras are smart enough to turn IBIS off automatically when they detect the camera is on a tripod (no wobble). However, it does no harm to do it manually. For sure IBIS, if enabled, will mess up long exposures on a tripod. I doubt it'd make much difference for short exposures.
     
    • Agree Agree x 1
  6. Joon525

    Joon525 Mu-43 Regular

    119
    Sep 24, 2012
    NJ
    feedback-loop.
    Turning IBIS off when on a table or tripod is the usual consensus.
    But after looking at your picture again I don't know if this is really the culprit. It looks like it chose a different focus point regardless of what you chose.
     
    • Informative Informative x 1
  7. Joon525

    Joon525 Mu-43 Regular

    119
    Sep 24, 2012
    NJ
    Yeah you are probably right.
     
  8. gryphon1911

    gryphon1911 Mu-43 Hall of Famer

    Mar 13, 2014
    Central Ohio, USA
    Andrew
    Best thing to do is to remove all possible things that COULD cause a miss focus, and IBIS turned on when camera is on a tripod should be the first thing. I would reshoot turning the IS to OFF and then report back if anything changes. I'd also shoot with the 2 second timer or a remote shutter release.
     
  9. Ian.

    Ian. Mu-43 All-Pro

    Mar 13, 2013
    Munich
    Ian
    I use a myset specially for tripod use. It switches IS off, anti-shock 1/8 on, ISO to 200 and other stuff I've forgotten.
     
  10. Bif

    Bif Mu-43 Veteran

    380
    May 28, 2012
    San Angelo TX
    Bruce Foreman
    Use manual focus. Autofocus is often not 100% accurate, subject tonal value contrast can have a lot of effect on accuracy of AF. Any closeup situation would be one case I would depend on MF.
     
  11. letsgofishing

    letsgofishing Mu-43 Veteran

    352
    Nov 21, 2012
    South Africa
    Mike Kaplan
    Out of interest, did you try a hand-held shot?
     
  12. budeny

    budeny Mu-43 All-Pro

    Mar 4, 2014
    Boulder, CO
    It's not clear what was the size of focus point on your shots.
    It also would be helpful to provide original, full sized jpegs, with full EXIF info, so we won't guess what other settings could cause such issue.
    Providing other parameters, like distance from lens to subject will help even more, as it looks to me 12-40 lens was on its limit of how close it can be to subject.
     
  13. PowerHawk2015

    PowerHawk2015 Mu-43 Regular

    35
    Mar 8, 2015
    Australia
    That isn't back focusing. The camera can't backfocus with a CDAF sensor, but can with a PDAF sensor.
    Are you using a single focus point? Reducing the size of the focus point helps placing the focus point on your subject more accurate, make it small. The focus point is probably just catching on the rear pecans. The AF system can be fooled by a challenging/unusual/tricky subject.
     
    • Agree Agree x 1
  14. pake

    pake Mu-43 All-Pro

    Oct 14, 2010
    Finland
    Teemu
    I've never switched off the E-M5's IBIS when shooting on tripod. No problems ever. Even the Finnish Olympus-expert Pekka Potka says you can leave it on.
     
  15. Drdave944

    Drdave944 Mu-43 Top Veteran

    697
    Feb 2, 2012
    I always get better results with manual focus for macro shots. The focus box is kind of dumb and likes sharp green lines, for some reason. I don't bother to turn off Image Stabilization. That is old hat.
     
  16. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    With detail work it may be best to go with the smallest Focus point. When you engage the focus point (either by selecting it in the quick menu or just tapping a direction on the navigation pad) you will see the focus point light up green. Then tap INFO and use the rear dial up top to adjust the size of the focus point to smaller then the perceived 'default' size. You will be able to choose more accurate focal points in this setting.
     
    • Informative Informative x 1
  17. Tapper

    Tapper Mu-43 Regular

    184
    Mar 12, 2013
    Please note: "On both cameras I used the small focus point, and the focus was set to the middle pecan piece."

    Thanks everyone for the ideas.

    It seems the camera is just somehow fooled by this subject. But after many tests it usually does well so I am not too worried.
     
  18. DigitalD

    DigitalD Mu-43 Top Veteran

    505
    Jan 10, 2014
    Miami
    David
    Oops. Sorry! :blush:
     
  19. stardealer

    stardealer New to Mu-43

    1
    Mar 14, 2015
    Yes it is fooled. If the small Focus point is the size you draw on the Pictures, your EM5 decided to focus on the cake slightly at the upper side of the pecan because of higher contrast. Remember that Olympus has coded CDAF in a way that it always searches for highest contrast in the area marked by the Focus Point and not for the nearest subject in this area.
    Therefore you could get pictures with focus sometimes at the cake and sometimes at the pecan, depending on the detected contrast in the specific moment right then.

    Your Sony decided otherwise.