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Bad copy or decentered

Discussion in 'Native Lenses' started by a_hit_of_meth, Sep 12, 2016.

  1. a_hit_of_meth

    a_hit_of_meth Mu-43 Veteran

    243
    Jan 7, 2012
    I picked up a used 25 1.8 yesterday which I really like, but I noticed on a few of the images the left side seems to be a bit softer compared to the right side at 100%. I couldn't be sure where the focus points were on my initial images that I took so I went back out and in between errands, I did some not so scientific tests shots on my E-m1 with a single focus point set in the middle, which is the only way I know how to test for this sort of thing.

    From what I can see it seems to be more noticeable with subjects further away and mostly under f5.6. It wasn't so bad when I first looked at the left side, I thought it was just normal oof blur, but when I compared it to how sharp the right side of the image is, I started to wonder if something might me a little off.

    I can't be sure what this is, or if I'm doing something wrong. I don't have time to post crops but I've uploaded some images on dropbox if anyone wants to have a look.



    Dropbox - P9122394.JPG
    Dropbox - P9122403.JPG
     
    Last edited: Sep 14, 2016
  2. christofp

    christofp Mu-43 Regular

    135
    Jul 21, 2012
    I had three 25/1.8 samples. Two from three samples were bad.

    The first was a very early sample, very good, better than the 20/1.7 I owned at that time, but unfortunately I had to sell it to fund my 40-150 PRO.

    One year later I bought a second one, very very decentered. Looked similar to your samples. Sent it back as "defect", no need for a prime lens that is inferior to a cheap kit lens.

    The lens in exchange was better than a kit lens but still much worse than my 12-40. I sent it back too and gave up.

    I bought a 15/1.7 instead.
     
  3. a_hit_of_meth

    a_hit_of_meth Mu-43 Veteran

    243
    Jan 7, 2012
    No chance I'll be getting my money back on this trade so I'll have to suck it up and cover the cost of repair. I just sold my second 25 1.4 earlier this year hoping to save some money while I considered switching to Fuji. I ended up buying an E-m1 instead which is why I went for this lens as a good, cheap prime. I wasn't really even planning on keeping this lens for more than a few months but now it will end up costing as much as a used 25 1.4, possibly more.

    I haven't read much about this issue, apart from the fact that one of the elements isn't lined up right which causes the problem, so I don't know what kind of repair it will require. Whether I will have to take it to the actual Oly service for specialist equipment like lasers and gauges, or if I can use a 3rd party repair service that costs a third of the price.

    For now I guess I'll just have to stop down most of my shots. It's not as obvious to me and most of the shots I have that show it, scenery and landscape type shots shouldn't be taken wide open anyway. The effects begin to ease up, but not disappear completely at around f4 and shots taken with the focus points on the left side are pretty sharp but I need to do more tests to determine the best way to make use of this lens.
     
  4. christofp

    christofp Mu-43 Regular

    135
    Jul 21, 2012
    Repair might be possible.

    When I bought the 15/1.7 in my fourth attempt, I got a lemon again.

    This time I did not give up but sent it for repair as it was under fresh warranty. The returned lens got a new optical assembly and this time, the lens was nearly flawless and at f1.7 as sharp as the 12-40/f2.8 .

    Happy end, finally!