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Thread: Image Discoloration

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    Image Discoloration

    Hello!

    I had a quick question regarding a discoloration in the center of my images. I had a shoot yesterday and noticed when I got home that some of my pictures had a blueish discoloration right in the center. Some of my shoots were inside, the only reason I can imagine is one of my strobes was pointed slightly at the lens. However, some of my shots were at the beach and had the same effect. I have never delt with this problem before, and it has nearly ruined my images.

    I did realize that I left my UV Filter on under my Polarizing Filter, possible conflict? Any help, or more info is greatly appreciated!

    This is causing me a ton of hours in post production trying to eliminate the discoloration!

    - Joel

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    Re: Image Discoloration

    it would be helpful if u posted a pic

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    Re: Image Discoloration

    Thanks. I didn't think about that.

    It stuck out like a soar thumb to me! In the center of the photos, you'll notice a circular blueish distortion.

    bad1.jpg

    bad2.jpg

    bad3.jpg
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    Last edited by Colin Southern; 3rd June 2009 at 04:56 AM.

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    Re: Image Discoloration

    Quote Originally Posted by jamays View Post
    I had a shoot yesterday and noticed when I got home that some of my pictures had a blueish discoloration right in the center.
    Hi Jamays,

    I can't explain why, but my gut instinct tells me that the UV and CP filters have something to do with it.

    This is more in to William W.'s territory than mine - I'll pop him an eMail for you to see if he'll take a look.

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    Re: Image Discoloration

    Thanks I appreciate that!

    Some more info: I am shooting with a Nikkor 50mm f/1.4 D on a D80

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    Re: Image Discoloration

    Hi Jamays,

    I'd say it definitely looks like a flare to me, as you guessed, with strobe or daylight.

    Apologies if this is stating the blinking obvious, but in my experience, to be this bad, there's usually a ruddy great blob of gunk on the filter, or lens front (or back?) element, might be a finger/thumb print or something else. Have you checked for this?

    I can't see it giving this distinct a pattern if both filters are the flat screw on type, I don't think they interact like this.

    And of course ALWAYS use a lens hood, not just outdoors in sunshine - because unless you are at the end of a long, dark tunnel, obtuse light will always be hitting the filter(s) and lens front elements (more in a zoom at wider angles, not relevant in this case I know) and this will contribute to vieling flare, even if it is only a little.

    BTW if you have a minute, please drop by the welcome thread and leave an intro - ta.

    Hope that helps,

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    Re: Image Discoloration

    Thanks Dave,

    The lens, UV, and CP filter were defintitly all clean. The lens hood is a good point I need to carry it around more! But what gets me is the flare is so distinct, circular and centered. It also did not show up on all the images.

    The filters are both screw on.

    - Joel

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    Re: Image Discoloration

    Are you able to reproduce it at all? If you can, then it should be a fairly straight-forward process to eliminate the various possibilities.

    Out of interest, what brand and model were the UV and CP filters?

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    Re: Image Discoloration

    Hi Joel,

    One other thought, is the lens 'new', or an 'oldie' being put to good use - if the latter, have you held it up to the light (not sun ) and looked through it? I am wondering if there is a patch of mould inside it. By now I'm clutching at straws, as you can probably tell

    Another straw: it hadn't been kept somewhere cold and brought to somewhere warm for the shoot and had condensation in (probably gone by now)?

    Obviously, do give Colin's idea a go too, this is additional.

    To be continued (I expect) ....

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    Re: Image Discoloration

    Quote Originally Posted by jamays View Post
    I had a shoot yesterday and noticed when I got home that some of my pictures had a bluish discoloration right in the centre. Some were inside, one of my strobes was pointed slightly at the lens. Some of my shots were at the beach and had the same effect. I did realize that I left my UV Filter on under my Polarizing Filter, possible conflict?
    What is the make and model of both filters?

    Is it on ALL of the images from that day with that lens?

    I am assuming it is not on all images from the wording of the question, but I am clarifying this point . . . because it could be important if specific images do NOT have this effect:

    It looks like Veiling Flare to me. It looks like there is a bounce of light into the rear of one of the filters: most likely from the front face of the UV into the rear of the PF.

    I suggest you eliminate this theory first.

    Were any of the inside shots taken without any Flash being pointed towards the lens, but with both filters on – even if is was not of this subject? i.e. same lens same filters with all the light sources essentially behind the lens / camera?

    If you have any shots on that day with that lens and filters attached, with a basically a front lit subject and there is no blue patch in those images, then I think you have your answer.

    If not, we need to look further . . .

    Looking forward to the answer.

    WW

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    Re: Image Discoloration

    Colin: "Are you able to reproduce it at all? If you can, then it should be a fairly straight-forward process to eliminate the various possibilities.

    Out of interest, what brand and model were the UV and CP filters?"


    - I was able to reproduce a flare similar to the problem before, if I have the camera at a 45 degree angle from the sun it seems a flare discolors the image in a similar way. See below.

    - The UV is a Tiffen and the CP is my back up, Promaster


    Dave: "One other thought, is the lens 'new', or an 'oldie' being put to good use - if the latter, have you held it up to the light (not sun ) and looked through it? I am wondering if there is a patch of mould inside it. By now I'm clutching at straws, as you can probably tell

    Another straw: it hadn't been kept somewhere cold and brought to somewhere warm for the shoot and had condensation in (probably gone by now)?"


    - The lens is old, and I have inspected it but can't see any sign of mold.

    - The moisture issue is a good point, but no the room my camera/lens is kept in is room temp, same as the studio.


    William: "Is it on ALL of the images from that day with that lens?

    I am assuming it is not on all images from the wording of the question, but I am clarifying this point . . . because it could be important if specific images do NOT have this effect:

    It looks like Veiling Flare to me. It looks like there is a bounce of light into the rear of one of the filters: most likely from the front face of the UV into the rear of the PF.

    I suggest you eliminate this theory first.

    Were any of the inside shots taken without any Flash being pointed towards the lens, but with both filters on – even if is was not of this subject? i.e. same lens same filters with all the light sources essentially behind the lens / camera?

    If you have any shots on that day with that lens and filters attached, with a basically a front lit subject and there is no blue patch in those images, then I think you have your answer."


    - No it was not on all the images fortunately, but was on some with only a slight angle toward the flash.

    - Yes with no light even remotely pointed toward the lens there was no discoloration which is why I leaned toward the flare answer - also with a black back drop there was no flare, even with the flash angled slightly at the lens.

    ----

    I had time today to do some trouble shooting. What I found was the lens seems to pick up the same bluish flare when at an angle (45 Degree) from the sky. This happened with all the filters on, off, or one at a time. I am assuming then that the filters aren't responsible.

    All your clarifying questions helped! I've attached some photos during my trouble shoot...

    My question now is why is my lens so sensitive? It seems that it will pick up a flare from all sorts of angles, which seems to limit my shooting options. I have done a lot of natural light shooting but have never come across this problem before. Any reason why this would appear to be an issue suddenly?
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    Re: Image Discoloration

    Hi Joel,

    If it is an oldie lens, I am now wondering if it has any multicoating (left on) at all?

    An uncoated lens would flare like this (I had one once).

    Quick test; when you look at the reflected image of a light source off the front or rear elements, do you see colours, green and/or magenta typically?

    Cheers,

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    Re: Image Discoloration

    Quote Originally Posted by Dave Humphries View Post
    If it is an oldie lens, I am now wondering if it has any multicoating (left on) at all?

    An uncoated lens would flare like this (I had one once).

    Quick test; when you look at the reflected image of a light source off the front or rear elements, do you see colours, green and/or magenta typically?
    Dave beat me to it. My thoughts too.

    Technically speaking most likely it is still predominately Veiling Flare - the direct light (more than 45 degrees front on), is bouncing around the front elements of the lens – and at different wavelengths, too.

    The other issue with an old lens is the quality of the light baffle - the fact that the inside of the lens is matt black - might be worn, or of poorer quality than what is now available: that might be compounding the effect of the assumed worn / damaged / poorer quality multi-coating.

    As to why it appeared so suddenly, if it is worn multi coating . . . I think we have to look at it this way:

    As things get old, there is a point in time when that age is noticed because of inferior performance, i.e. there has to be a “first”. The point is, there might be other images where the problem is present but the subject did not highlight the issue easily or the scrutiny was not as severe.

    I think the fact that the result is isolated and able to be repeatedly reproduced by a set of controlled conditions now puts the problem to bed, whatever we might like to define it as technically.

    The “up side” I see is, if it is the multicoating gone; the lens is not the most expensive in the Nikkor line-up.

    I know you haven’t asked this, but if it were me, and it proves to be the multicoating issue, I would be replacing the lens rather than juggling and guessing when and in what situations it can or cannot be used.

    Thanks for the precise feedback Joel, good luck.

    WW
    Last edited by William W; 3rd June 2009 at 09:48 PM.

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    Re: Image Discoloration

    Thanks for all the help! William, Dave, and Colin!

    I've arranged to borrow a good friends Nikkor 50mm f/1.4d so I can do the same shots and see if its the coating. I'll let you know how it turns out.

    - Joel

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    Re: Image Discoloration

    Quote Originally Posted by jamays View Post
    Thanks for all the help! William, Dave, and Colin!

    I've arranged to borrow a good friends Nikkor 50mm f/1.4d so I can do the same shots and see if its the coating. I'll let you know how it turns out.

    - Joel
    No worries Joel, although I wasn't much help on this occasion!

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