Fringing?? NOoooooooOOO!!!

Discussion in 'Photography Beginners' Forum' started by Aayria, May 23, 2010.

  1. Aayria

    Aayria TPF Noob!

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    Yesturday I was the photographer for a golf benefit/ fundraiser dinner for an amazing family and their father's battle with cancer.

    There were over 40 teams present, with four people on each team. (TONS of golf carts LOL!)

    I'll try to post more pictures from the event, but right now I'm just trying to sort through and do some basic edits in light room..

    In editing, I came across something on this picture that I'm a little worried about. If you zoom in on the lettering of these hats, it's really easy to make out distinct purple fringing around each letter! I've never noticed this with my lens or camera before, unless I was using the kit lens. This picture was taken with my 50mm 1.4 AF-S (the new one from Nikon.)

    Do you guys think this was caused by the lens, the light, or something else I"m not considering???

    Here's the picture, sorry for the size, I wanted to make sure you could see the purple:

    [​IMG]
     
  2. JasonLambert

    JasonLambert TPF Noob!

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    *bump* I would like to know the answer to this as well.
     
  3. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Yes, purple fringing. It is almost always caused by the lens.

    It's characteristic of fast primes and most notable in high contrast areas and at wide aperture settings. You have both in this image: White type on black and a wide aperture.

    Shallow DOF is to often way over done today or done with the wrong focal length for the subject, IMO.

    http://en.wikipedia.org/wiki/Purple_fringing

    Edit: I forgot to mention it's a quick and easy fix using ACR (Lens Corrections tab) in PS/CSx.
     
    Last edited: May 23, 2010
  4. Aayria

    Aayria TPF Noob!

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    Thanks so much for the reply! I understand what you mean about shallow DOF being used too often, and I fall into that trap quite a bite because I really love the effect, especially for candids with children or babies. (and cowboy hats apparently lol ;) )

    I'll keep a watch on my settings when shooting things with high contrast with such bright light and an open aperture in the future... I think the letters were probably blown out as well, but I couldn't tell because they were already white.

    Thanks again, you're always so helpful!
     
  5. sleist

    sleist Been spending a lot of time on here!

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    Well said. It's a lesson I've been learning the hard way. I've been forcing myself to learn the sweet spots of my lenses and think about whether a shallow depth of field is really the best presentation for my subject.

    I think it may be related in some way with this love afair people seem to have with the 50mm (not the same on a DX body as on FX). That and bokeh. I like a shallow DOF and bokeh, but I've screwed up more pictures chasing this than I care to mention - particularly when you consider I prefer natural light and use a tripod far less often than I ought to. I work hard at trying to remember how much I hate lack of sharpness and CA. Then, if I'm lucky, I might actually get out of my own way and make a decent exposure.

    ;)

    By the way - the green fringing on the lettering on the left side is caused by the same issue - in case you didn't notice that.
     
    Last edited: May 23, 2010
  6. Derrel

    Derrel Mr. Rain Cloud

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    erose86, chromatic aberration is divided into two types, lateral, which can be removed by software adjustment or by in-camera software processing in newer models of Nikon d-slr cameras, and longitudinal chromatic aberration, which can not be removed by software, in any form.

    Longitudinal chromatic aberration usually takes the form of green and purple color fringes, located in front of the plane of sharpest focus, and behind the plane of sharpest focus...because it often shows up in wide-aperture photos, this type of CA is often called "bokeh chromatic aberration" or simply "bokeh CA". Some lenses have pretty noticeable longitudinal CA at their wider apertures. Canon's 85mm f/1.2-L at 1.2 and 1.4 for example, have pretty notable longitudinal CA on some subjects. Nikon's 85/1.4 AF-D also shows this.

    On cheaper tele-zooms, like 70-300 lenses that cost $129-$199, there is often a pretty fair amount of lateral chromatic aberration at the longer focal lengths especially. On kit lenses like the 18-55 EF-S, lateral CA is quite present. Better, longer lenses will sometimes be designated "APO", like Sigma's 70-300 APO. APO stands for apo-chromatic, and apochromatic lenses are supposed to be able to bring light of the primary colors to the same,exact point of focus, thus eliminating CA.

    The best way to avoid CA is to buy lenses that do not suffer from it in the first place. Careful lens test reports will almost always have a section devoted exclusively to CA and its tendencies and type.
     
  7. dhilberg

    dhilberg TPF Noob!

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    Another way to remove the purple fringing is to add a Hue/Saturation layer, select blues from the drop-down menu, select the eyedropper tool, sample the area with the CA (blow it up to like 800% to make it easier to see individual pixels), then drop the saturation of that color down. Repeat with a new Hue/Saturation layer for any shades left over. The problem with this method is that it will desaturate all areas of the photos with similar color. But it would work perfectly on the image you posted above.
     
  8. gpardo64

    gpardo64 TPF Noob!

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