Strange optical defect on new Nikon 50mm 1.8

Discussion in 'Nikon' started by james_smith|55, Nov 6, 2011.

  1. I purchased a Nikon 50mm 1.8 a few weeks ago and I've shot a few rolls of film with it. After shooting an IR roll I noticed a strange streak of light in the upper left hand quadrant of numerous frames on the negative. It was always in the same place and varied with intensity with exposure. Regardless of my orientation to the sun the streak of light appeared in the exact same place. I did not notice any hot spots with the lens. I thought it was perhaps a defective IR filter. A few weeks later I did some shooting with a deep red contrast filter from another company. The IR filter was one of those cheap ones from ebay but the deep red contrast filter was an expensive coated filter purchased from B&H. The same streak of light appeared in the exact same place again. I haven't tried shooting a roll with another lens yet. I guess that is the next step. Has anyone seen anything like this before?
    The IR film was efke IR 820. The B&W film was efke ISO 25. The efke IR film was sent out to be processed. The efke 25 was processed in a school darkroom by a friend. I'm baffled. I don't see the streak when I'm shooting without a deep red filter or IR filter.
    00ZZDF-412983584.jpg
     
  2. Here is the deep red filter version.
    00ZZDQ-412985584.jpg
     
  3. Does it appear if you shoot in 'portrait' orientation?
     
  4. If this is only in IR, certain lenses are well known for having 'hot spots' or flare for IR that don't show in non-IR work (for example, an old list at http://dpanswers.com/content/irphoto_lenses.php where the Nikon 50mm f/1.8 G AF-S is mentioned as having "poor IR" qualities).
    Otherwise:
    Not on other lenses with the same camera? No chance that your camera has developed a modest light leak?
    Any shiny debris in the lens when you look into it?
     
  5. Les Berkley,
    I haven't shot any subject matter in portrait mode that would have a sufficiently dark and smooth background in that area to show the light streak. Frankly after the first roll of IR I thought it was the IR filter. I only happened to notice the same thing happening with the regular B&W film using a deep red filter by chance. I had already exchanged the IR filter and assumed my problem was solved.
     
  6. von Weinberg,
    Thanks for the reply. No my Nikon 50mm 1.8 AF is the one that is shown as being good for IR. Plus that light streak doesn't appear to be in the "hot spot" pattern. Plus if you look closely at the second picture taken with efke 25 you can still faintly see the streak.
    I thought about the light leak possibility but the streak appears in every frame in the exact same place if there is a fairly uniform dark subject in the right place. It also varies with length of exposure. The longer the exposure the more intense the streak. I don't know about debris in the lens. It's new and I thought it just wasn't clean, but I inspected it and couldn't see a thing. I thought perhaps there is some kind of optical flaw
    I haven't tried the camera with other lenses. I suppose that is the next step.
     
  7. Looks nearly identical in both photos. I'd look for a cause other than the lens or filter.
    What camera body are you using? Also, check the leader and tail of the roll, if you kept 'em. Check to see whether the same artifact appears on parts of the film that weren't exposed in the camera.
     
  8. Jenkins,
    The camera is a Nikon FM10. I am not sure how old it is because it was purchased used from Ebay. It doesn't appear to be too old or abused.
    I kind of ruled the filter thing out because the light streak appeared in the same place with two different filters. I don't know about the light leak possibilities. I remeber when I first saw the light streak I examined the whole roll of film very carefully and the parts of the negative that weren't intentionally exposed were pristine... leader, rebate, everything. Actually I used pretty much the entire roll of IR film because I loaded it in a dark bag. There were no unexposed frames and only a small leader. I don't recall what the leader looked like on the non IR B&W film. I'm going to have to do a test roll with a different lens. I'll be sure to check the leader and rebate.
    I'll get back to you guys after I have test results. It may be a little while. I'm busy with work.
    Thanks for the suggestions.
     
  9. This video is interesting. Although the construction of that lens looks very different from the Nikon 50mm 1.8. The 50mm 1.8 that I have does not have a focus finder window.
    [​IMG]
     
  10. I just thought of something. Maybe I should cover up the eye piece when I am doing longer exposures. Maybe there is a light leak from there.
     
  11. The easiest way; place a cheap film, and point a strong torch light to every hole in your camera, with or without lens.
    You can test it in different frames, isolating different areas with the cap, blackout tape, film changing bag or whatever.
    If you suspect from the eyepice area, isolate the rest of the camera and point the torch to this area, thoroughly.
    Don`t mess with it; once you receive the developed film, you´ll exactly know where is the problem.
     
  12. Wouldn't a light leak show up as a dark streak ?
     
  13. I still incline just a bit to the IR flare explanation
    --wondering how much the red filter on the Efke 25 is getting some IR sensitivity in the B&W film to show up? Anybody have any info on how IR sensitive regular films are?
    Maybe try a ND filter and see what happens?
    Certainly hope you'll keep us informed as you test the options. Thanks.
     
  14. Do you not simply have another lens you could try?
     
  15. As a first step, I would try the lens on a different camera, and the camera with a different lens. This will isolate the problem. Then you can work from there.
     
  16. My money is on a problem with the camera, not the lens.
     
  17. i have this lens and i've never seen that kind of flare, though i shoot digital with a nikon D5000 still no flare whatsoever, im going for a problem with the camera too, or a leak
     
  18. Bill: You had me going there for a while.
    No, a light leak would produce a dark streak on the negative, which would become a light streak when converted into a positive.
     
  19. Jaime Ordonez,
    I shoot on a 35mm film camera (ie full frame). Most of the anomaly probably wouldn't show up on the cropped sensor of a Nikon D5000. Secondly the anomaly doesn't show up on the vast majority of my pictures. It only appears in certain situations. As the attached images illustrate it was most intense when I was shooting IR film through a lens filter that is visibly opaque (ie 760 nm cut off). I would hazard to guess that 99.9% of people that own this lens do not use it in this fashion and would not get those results. The other place where I see the anomaly but much more faintly is when shooting ISO 25 film with filters resulting in 3-4 stops of exposure compensation. It is no where near as intense as the results when shooting through an visibly opaque filter but it is visible if you know what to look for. Also the type of scene and camera orientation seem to play a role. The anomaly is probably still present but if that part of the scene is busy and I'm shooting visible light then I can't really make it out. I am also concerned about my copy of the lens and my camera. My results don't necessarily have any implications for your equipment. The lens is a 50mm prime. I'm pretty sure Nikon has worked all the bugs out of the design ;)
    I am going to try and stress test the camera and lens as other have suggested in this thread. I wish I had another Nikon film camera to test the lens out on. Hopefully sometime next week I will have some new scans to upload and I will let you all know how the detective work is going.
     
  20. No need to throw away your Nikon 50mm AF 1.8. I finally did the stress test and in every scenario the light streak appeared. I tried a different lens. I tried covering up the eye piece. I even took a shot with the lens cap on. In every single scenario the light streak was present. Apparently something somewhere on the camera body is leaking. I did not take the advice on one of the posters and shine a strong light on various parts of the body to find the leak. Where ever it is it is tiny and only shows up under extreme conditions. Thanks for all your help guys.
     

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