Nikon 50mm 1.8d purple fringing

Discussion in 'Nikon' started by peterkp, Apr 27, 2017.

  1. Hi, does anybody else have horrendous CA or fringing on their 50mm 1.8d? And how do you fix it? I can't seem to find anything mentioned in comparisons etc. I've tried to upload an image but the site won't let me.
    Thanks,
    Peter P.
     
  2. No visible fringing on images made with my copy of 50mm f/1.8D. But then again recent cameras might have more resolution than mine.

    Some raw converters are very good at reducing fringing, even free Capture NX-D has tickbox for it in processing settings.

    Some gopro images have heavy blue fringing on high contrast edges, older Capture NX2 was very good at taming them.
     
  3. Almost every lens show a degree of CA; I don`t remember the 50/1.8AFD to be the worst in this respect (instead, I remember it for its bokeh rendition).
    I`m pretty obsolete in equipment and techniques, but if shootingt NEF, my Nikon editing software have some tools to help in this respect.
     
  4. SCL

    SCL

  5. SCL

    SCL

    Not sure why this repeated.
     
  6. I have the plain old AF version, not D, and it doesn't show "horrendous" CA at all on my D800. Of all its faults CA is perhaps the least.

    Overall it's not a bad lens at all. Maybe you have a bad or damaged sample?

    Images posted inline can only be up to 1000 pixels wide/high, and under 1megabyte in file size.
     
  7. Hi All, thanks for the replies. I've managed to upload a sky that I shot with the lens and my D800E (and yes, I know there's some dust spots). When I'm in ACR or photoshop, the tick boxes seem to do very little, if anything, to reduce the CA. When I look at tutorials online to reduce fringing they seem to deal with very narrow fringing on edges, not the large amount I have. Maybe rodeo_joe's right, I have a dud lens? Quite like it otherwise.
    Peter P.

    skyCA.jpg
     
  8. There is possibility of fungus. You could open the aperture and check lens outer rim against white light and UV-light.
     
  9. Ok. So the corners have a magenta tint. CA fringing only appears around edge detail, not as a colour cast. I see no sign of fringing on the white clouds. This has to be something other than CA.

    Did you use a polarizer by any chance?

    Small amounts of fungus that aren't immediately obvious by looking through the lens would have almost no effect on the image. It certainly wouldn't turn the corners purple.
     
    Last edited: Apr 30, 2017
  10. Thanks hapien and rodeo_joe|1.

    I'll have another close look at the lens. No, no polarizer used. I called it CA, for want of a better description, because as you say CA is normally around edge detail. I'll see if I can get a response from Nikon.

    It's only a problem when I shoot something like this, but then it's a big problem.
     
  11. Mine has quite a bit of fringing wide open, but it goes away quickly a stop or two down. Is near wide open where you are experiencing this? The solution is, I guess, to stop down or get a better lens?
     
  12. What I see in the image above is not "purple fringing," rather a color cast which increases from the center to the edges of the image. From what I have read, this is related to the increasing angle of incidence away from the center of the image, based on the position of the exit node of the lens. The closer the node to the sensor, the greater the angle of incidence at the edges. It is due to a combination of factors, including refraction in the cover glass and filter, and parallax between the Bayer filter and sensor, and vignetting. The last is probably the most significant, since the color gradient (and vignetting) decreases as the aperture is closed.

    Vignetting can be corrected in Lightroom based on the lens profile, or manually.

    I'm surprised to see it in a DSLR, since there is so much distance between the lens and sensor, It is a bothersome effect in mirrorless cameras, including digital Leica M cameras. Leica corrects the image in firmware, based on a library of lenses in the menu. The lens type is detected from dot codes on the mount, or entered manually.

    "Purple fringing" was a problem a few years back, and appears as a purple flag on bright objects toward the edge of the image. This was supposedly due to Bayer filter parallax, and was more pronounced in Canon cameras at the time.

    Neither phenomenon is related to chromatic aberration, which is seen as a narrow band of color on edges, red on one side and purple on the other.
     
  13. Have a look at any vignetting auto-reduction settings in the camera and LR. It looks to me as if the edge/corner darkening, seen with this lens at wider apertures, is being lightened, but turned magenta in the process.

    The lower corners actually look lighter than the centre, which is odd and not what I'd expect to see at all.

    Turn off any vignetting correction you can find and see if that cures the purpleness.
     
  14. thanks for the comments and suggestions. I'll play with vignetting controls.
    Peter p.
     
  15. thanks Michael. But the image was shot at f8 and 1/500. I'll pay some more attention to f-stop and see how/if it varies.
     
  16. thanks again to everyone for their thoughts. I've had a look at the image in photoshop (don't use LR) and playing with the amount and midpoint in the "Custom" "Lens Correction" sort of helps. "amount" just turns the purple to white after a point, but midpoint helps as well. I had the vignette control on "normal" on the camera. It's off now and I'll see how I go.
    Peter P.
     
  17. Question : Are you using a lenshood ? And if not could you try again in similar circumstances if a lenshood helps reducing thuis effect ?
     
  18. no, I don't use a lens hood for this lens as the front element is well recessed.. I use one for all other lenses. I'll see if I can find one locally and try.
     
  19. Hi, for those interested, I did eventually get onto Nikon support. After harping on about the fact that I don't use a lens hood for this lens, I asked why they had no other suggestions and if they had seen this before. They then seemed to think it does look like there's a problem with the lens. Maybe with the coatings. They didn't suggest if it was damage or a problem in the manufacturing process.
    I did take a series of shots, and told them, of the sky at different angles to the sun at all stops - f22 to f1.8 - and the fringing was evident at all f stops. I can't replicate the problem with other lenses I have when used without a hood. I was a bit annoyed that they initially offered no other suggestions and implied it was my fault for not using a hood. I thought this was nonsense. Don't know what you guys think about that.
    Anyway, happy shooting.
    Peter P.
     

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