28-70 misbehaving

Discussion in 'Lens Lust' started by Beezle, Sep 29, 2005.

  1. I've been using a 28-70 for a couple of months now. Quite happy with it though a few problems:

    - strong blue CA in images with bright blown out edges. Hasn't happened in a shot that mattered, so not a big deal. But I am surprised to see this. I have never seen this with the 17-55 or 70-200. Normal CA removal didn't seem to clean it up either.

    - the focusing ring became really stiff yesterday in use. Not so stiff I thought I might break something turning it, but pretty darned stiff. I am a rather burly man, so it isn't a mild muscles thing. I left it be and AF worked fine. After a while I tried gently using it again and it resumed its normal amount of tightness and smoothness.

    So far as I know, nothing drastic has happened to this lens. It was sent to me directly by Nikon, and it gets the normal treatment for such expensive things.

    Has anyone else seen the latter? I'm not figuring on sending it in for that, but I wonder if it just needed breaking in or if it will end up needing servicing. These days I manually focus quite a bit (yay DK17M).

    Thanks,

    Ed
     
  2. JeffKohn

    JeffKohn

    Apr 21, 2005
    Houston, TX
    I haven't seen much of this with the 28-70 (just finally got it back from Nikon Repair today), but I have seen it some with the 85 1.4. There was a discussion about this on DPR a while back, I believe somebody said it's actually spherical aberration, not CA. Unless we're talking about two different things. What I'm referring to only tended to show up along high-contrast transitions in out-of-focus areas.
     
  3. Thanks for the reply. Here are a few examples of it:

    [​IMG]
    [​IMG]

    If you don't mind my asking, what as yours in for?
     
  4. That seems like extremely severe CA. I dont think even my 70-300 ever exibited that much CA. I'd bet there's something wrong with the ED element. The ED element is there to eliminate this exact problem, isn't it?
     
  5. Looks strong to me, but many of the images I've taken with it with similar highlights and contrast show none of this.
     
  6. Hmm... that looks more like blooming than CA, given the brightness of the highlights involved.
     
  7. Perhaps we should call it BLUEming? :biggrin:
     
  8. Hi, Ed! I'm back east on holiday right now, but I'll check in with you when I return next week. If we can get together, I'll let you try my 28-70, and compare results with yours on identical compositions. That should determine if you have a problem with your lens, or if it's a generic problem. But from the stiffness of the focusing ring you described, I'm thinking you have an alignment problem with your copy.
     
  9. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Dear Ed,

    this maybe dirt inside the lens, some defect in lens assembly, or problem with raw conversion. It does not look like CA at all. Is any of raw files available for analysis to rule the conversion problem out?
     
  10. JeffKohn

    JeffKohn

    Apr 21, 2005
    Houston, TX
    That doesn't look like the problem I was talking about, I agree with the others that looks more like sensor blooming or CA. As Frank said given the fact that you also have a potential problem with zooming, maybe your lens needs checked out. Comparing to another 28-70 is a good idea if you can arrange it.

    Being the klutz I am, I dropped it and mucked up the zoom mechanism at the very least. Repair bill was $450 but fortunately the lens was only a few weeks old so AMEX will cover the repair.
     
  11. I have seen it happen in a JPEG. I also tried three converters (CS, NC and another) and the color remains.

    I could put a file on my server if you would like to see one.
     
  12. That would be nice. I appreciate the offer. Would be nice to meet you too.

    I will come up with a reliable way to reproduce it.
     
  13. Just tried the lens on my D70 just to see (usually used on a D2X or a D50).

    I can reproduce it reliably shooting the shutters you see in the example above. But I also was able to get a shot without any of the blue color. Not sure why.

    The lens' inner barrel has had a rattle to it since day 1, as well as the focus ring and these odd blue highlights. I am thinking I will just send it off to Nikon.

    Oddly enough, a new 17-55 arrives from KEH today. While I like the 28-70, I missed having the wide end and something about the DX just made me buy a 2nd one (the 28-70 was a swap for a 17-55, which I had focusing problems with).

    I really need to move closer to Nikon service. :rolleyes:
     
  14. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Yes, please - I really want to see the NEF. The good test for this types of the effects is scrunched aluminum foil under flash
     
  15. Thanks for the help everyone.

    It just so happens I noticed a young man in a bathtub wearing a foil hat...

    [​IMG]

    But I do not see the effect! I will try some other subjects. Perhaps something is loose in this lens?

    Also, I am putting the NEF that the above leaf crop came from on my server and PMing you the URL to it.
     
  16. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Lovely! But try overexposing that foil :) I got your PM, thank you.
     
  17. Here is a 100% crop of one I shot overexposed. The NEF is on its way to that directory on my server.

    [​IMG]
     
  18. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Sorry to say this, but the captured data indeed contains blooming. Specular highlights around sharp bends having bluish tint usually is the result of lens/aperture misalignment or reflections from dust inside the lens. I would suggest trying other lenses and maybe another sample of the same lens in the same test.
     
  19. Thanks for looking at that.

    This lens is only about a month old, and with the other symptoms it is exhibiting, I have to conclude that it needs mechanical repair of some sort.

    It looks okay, but I suppose it could have been abused during shipment. Or perhaps something just came loose. In any case, it is off to Nikon for a look.

    I did try the same test with a 17-55 DX, and I saw none of this. Also happy to say this new 17-55 focuses quite differently from the original I had.
     
  20. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Ed,

    You can burn the nef with blue foil and jpeg from NC to CD to accompany the lens.