Focus issue with 9-18mm f/4.0-5.6 (Four Thirds) - faulty lens...?

Discussion in 'Adapted Lenses' started by jamespetts, Sep 21, 2016.

  1. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    I have noticed a rather curious thing in one of my photographs taken with the E-M1 and the Four Thirds 9-18mm f/4.0-5.6:

    29550470520_312e174a6e_h.jpg Hills and stream by James Petts, on Flickr

    The rocks in the foreground and the valley/trees in the background seem to be more in focus than the rocky outcrop/hilltop to the centre left. I am not quite sure how this can be: the focus, I think, was on the rocks, but this was taken at 9mm and f/5.6, so there should be a reasonably decent depth of field. Camera shake seems to me extraordinarily unlikely at 1/125 at 9mm with 5-axis stabilisation.

    Could this be a sign of a faulty lens? I bought it secondhand some years ago when I first got the E-M1. It has never been as good as some of the higher end lenses (I have to add quite a lot of sharpening in post usually), but it can give decent results sometimes.
     
  2. SVQuant

    SVQuant Mu-43 Top Veteran

    998
    Sep 20, 2015
    SF Bay Area, California, USA
    Sameer
    There were a couple of threads about generic 43-m43 adapters being a little off-plane and this effect being most visible in wide lenses. If you are using a generic adapter, that may well be the case here.
     
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  3. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    Thank you for your reply. I am actually using a genuine Olympus MMF-3 (as I also use it with the weather sealed 50-200mm f/2.8-3.5 and MC-14), so it is probably not the adapter.
     
  4. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Try a brick wall... make sure you're lined up and level.

    Could still be an issue with the adapter btw, wide angle lenses are much more susceptible to being off -plane.
     
  5. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    I have now had a chance to take some brick wall pictures with this lens. I have no idea how to be sure of being absolutely perpendicular, but here are the results at at both ends of the zoom range at maximum aperture with no sharpening in post:

    29926208525_99a05d7e2a_h.jpg Brick wall by James Petts, on Flickr

    29299510023_98a36ad237_h.jpg Brick wall by James Petts, on Flickr

    29299523323_caa8c5c65a_h.jpg Brick wall by James Petts, on Flickr

    29299537713_9fc46950d1_h.jpg Brick wall by James Petts, on Flickr

    29891508926_e0ba9fa790_h.jpg Brick wall by James Petts, on Flickr

    Do any of you see anything significant in these?
     
  6. PeHa

    PeHa Mu-43 Veteran

    234
    Nov 12, 2013
    Uppsala, Sweden
    I also have the FT 9-18 and two Oly adapters where I've noticed that one is better than the other. It's true as stated above that wide-angle lenses is much more off-plane sensitive than tele which explains why you haven't seen it with the 50-200. I've tried with AF-adjustments in the E-M1 to see if there's a point where it's acceptable alla over the image though it's not a real solution. If you have access to a FT camera you can check if the lens itself is ok (I have an E-620 on the shelf). Otherwise, of course, get another adapter...
     
  7. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    Do you think that this is a faulty adapter?
     
  8. PeHa

    PeHa Mu-43 Veteran

    234
    Nov 12, 2013
    Uppsala, Sweden
    Well, the images look weaker on the left side, typical for off-plane caused by the adapter...
     
  9. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    I see. I shall have to look into that. Thank you.
     
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  10. jamespetts

    jamespetts Mu-43 Top Veteran

    805
    May 21, 2011
    London, England
    After having read some articles on lens decentring, suggesting that ultra-wide angle lenses, zooms, and lenses with plastic bodies were particularly susceptible to this phenomenon (and noting that this lens is an ultra-wide angle zoom with a plastic body), and that this can cause exactly these symptoms, I took the lens into the London Camera Exchange on the Strand (where I bought the adapter) to see whether anything could be done (and also to try to test the lens with a Four Thirds body, if they had one in stock, to check whether the adapter was the problem).

    They did not have a Four Thirds body in stock, but the assistant noted that the front of the lens seemed to wobble slightly, and noted that even a tiny movement could cause problems with image quality (as indeed I had read in the articles). We managed to get the plastic ring around the outside of the front of the lens off (cracking it in the process; this was my over-enthusiastic removal of it rather than the assistant's; happily, this is only a cosmetic issue) and the assistant found a screwdriver that fitted the tiny little screws that were revealed by the removal of this ring. He found one screw that was a little loose, and tightened it. However, the front of the lens still seemed to wobble. I put the plastic ring back on, and looked at some other of the ultra-wide angle zoom lenses that he had in stock. I did not buy anything immediately, as I wanted to give the matter further consideration, but I did try out the PRO 7-14mm f/2.8 and the m.Zuiko 9-18mm f/4-5.6.

    On returning home and checking my pictures taken in the shop, I was surprised to find that the problem with my own lens did not seem apparent on the one photograph that I took with it (of a display cabinet with filters and boxes of film). It actually appeared sharper at the edges than the photograph of the same scene than I had taken with the 7-14mm PRO lens, but looking at that photograph carefully, it seems to be affected by motion blur at the edges (implied by a directional ghosting in high contrast areas rather than consistent blur, although it is somewhat odd to have had that at 1/60th of a second with the lens at 9mm and 5-axis stabilisation enabled, with the camera resting on the counter). Further photographs taken of my bookshelf just now seem more or less consistent: there is no significant blur on the left hand edge that I can find, although I am not equipped to test this with precision (albeit any problem that can only be spotted by testing with precision is not the most serious of problems in the first place).

    I wonder whether the screw tightening might have helped after all...?
     
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