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Thread: purple highlights

  1. #51
    Jamesmd
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    Re: purple highlights

    Thanks so much Eoin . I'll do exactly all you said and , practice , practice and practice .
    Cheers .

    James

  2. #52
    Senior Member douglasf13's Avatar
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    Re: purple highlights

    Eoin is right on. Longitudinal CA isn't uncommon in wide aperture lenses, and overexposure can be the culprit. However, remember that most scenes require the overexposure of specular highlights in order for the rest of the scene to be exposed correctly, so you'll probably have to except some CA lots of times in those areas, and hopefully it is either unnoticeable or removable if it bothers you. You don't want to get into the practice of not blowing any of your speculars, or you'll end up with really dark, noisy pics. Jeez, that's a lot of double negatives. Sorry.

    The UV filter thing may be an interesting development.
    Last edited by douglasf13; 17th June 2009 at 11:23.

  3. #53
    Jamesmd
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    Re: purple highlights

    for the tests I'm doing , the thing is avoid great dynamic range under F 2 and everything seams ok .

    Thanks guys .

    James

  4. #54
    Senior Member Braeside's Avatar
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    Re: purple highlights

    There is a good test of this (and other lenses) at this site

    Note the Long CA they show.
    David Anderson

  5. #55
    Super Duper
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    Re: purple highlights

    Quote Originally Posted by Jamesmd View Post
    I've just done the same shot with and without VU and its worst with.

    Ill send pics right now .

    Can you do similar test to se if you have it ?

    its 100 ISO , 1,4 F .
    This proves nothing. The two photos are different. Look at what is in focus and is not between the two images.

    LoCal shows up in the OOF Bokeh ... and the second shot is more OOF which has nothing to do with the filter.

  6. #56
    Jamesmd
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    Re: purple highlights

    Fotografz , you are right .I'll do them propperly with tripod and manual focus for conditios to be the same .

    Thanks braeside .

    Cheers

    James

  7. #57
    Senior Member douglasf13's Avatar
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    Re: purple highlights

    Yep, that's why I said "maybe" I'm not crazy Tripod test with the same lighting conditions needs to be done on multiple scenes.

  8. #58
    Jamesmd
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    Re: purple highlights

    ok , here is the test .

    the pics on the left without VU it says anyway .

    I think it means that filter doesn't change things and that CA disappears at f 5,6 +/-.

    Hope its any good .

    Cheers

    James

    PDF to big !!! ill have to do something

    just a sec

  9. #59
    Jamesmd
    Guest

    Re: purple highlights

    lets see now
    Last edited by Jamesmd; 13th October 2009 at 05:21.

  10. #60
    Jamesmd
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    Re: purple highlights

    Hi , so , its not very useful I see.

    cheers

    james

  11. #61
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    Re: purple highlights

    The ZA 85 has more LoCA than the 135 1.8.
    Photozone.de site review for the 85 1.4 has white ruler test shots showing the LoCA at different apertures.

  12. #62
    Senior Member Eoin's Avatar
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    Re: purple highlights

    Quote Originally Posted by Jamesmd View Post
    Hi , so , its not very useful I see.

    cheers

    james

    James the problem is the images are to small for me to even see purple fringing in them (could just be me and my Laptop).

    Wayne, I think the 85 is more prone to purple fringing wide open compared to the 135, but one has to consider it's also a stop faster and twice the light hitting the sensor.

    But I do think they are about the same for LoCA when the apertures are the same in the Photozone test. But in real world situations, I haven't come across it.
    A7II, FE 35, 55 C/Y 18, 28, 85, 100, 28-85

  13. #63
    Jamesmd
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    Re: purple highlights

    [QUOTE=Eoin;110011]James the problem is the images are to small for me to even see purple fringing in them (could just be me and my Laptop).

    Hi Sir , I think you can download the PDF , its bigger

    Cheers

  14. #64
    Super Duper
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    Re: purple highlights

    Quote Originally Posted by Eoin View Post
    James the problem is the images are to small for me to even see purple fringing in them (could just be me and my Laptop).

    Wayne, I think the 85 is more prone to purple fringing wide open compared to the 135, but one has to consider it's also a stop faster and twice the light hitting the sensor.

    But I do think they are about the same for LoCA when the apertures are the same in the Photozone test. But in real world situations, I haven't come across it.
    I've seen it a lot in real world conditions while shooting weddings. White dress against darker backgrounds producing more cyan fringing than purple. No huge deal since C1 deals with it pretty well in most, but not all, situations.

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