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Thread: Infrared and hotspots

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    Super Duper
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    Infrared and hotspots

    I am looking to collect information on lenses that give "hotspots" while shooting in infrared. Among the lenses I use, I know which ones do this and which do not. I am not looking for a lens list but the possible contributing factor(s)

    There are theories on lens' coatings affecting their IR performance, particularly when it comes to "hotspots".

    Are there any other reasons/possibilities that contribute to this? Your thoughts, please.


    Sigma 30/1.4 @ f/1.4, D200-IR, ISO640

    The Sigma 30/1.4 shows no image degradation at all from f/1.4 to f/8. After that (when stopped down) things get mushy.

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Infrared and hotspots

    On the Leica M system all of the ASPH lenses seem to create hotspots. So i would assume this would be the case with others as well.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: Infrared and hotspots

    Thanks for your thoughts, Guy.

    It is a different world with a dedicated IR cam.

    I have used my Epson R-D1s for IR (and my old D70) but without the AA/IR cut filters on the CCD, it is like getting brand new eyes.

  4. #4
    diglloyd
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    Re: Infrared and hotspots

    Quote Originally Posted by Vivek View Post
    I am looking to collect information on lenses that give "hotspots" while shooting in infrared. Among the lenses I use, I know which ones do this and which do not. I am not looking for a lens list but the possible contributing factor(s)

    There are theories on lens' coatings affecting their IR performance, particularly when it comes to "hotspots".

    Are there any other reasons/possibilities that contribute to this? Your thoughts, please.
    It is a combination of factors. I assess over 50 lenses in my Guide to Digital Infrared eBook at diglloyd.com (not free).

    But a large factor is the lens coatings, which is unequivocally true; see my (free) review the Zeiss ZF Prototype Lenses for Infrared.

    Zeiss has still not made a decision as to whether to produce versions of the ZF lenses for infrared (industrial) use. I hope they do, because the prototypes I used were fantastic.

  5. #5
    diglloyd
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    Re: Infrared and hotspots

    Quote Originally Posted by Guy Mancuso View Post
    On the Leica M system all of the ASPH lenses seem to create hotspots. So i would assume this would be the case with others as well.
    Probably even the non-ASPH do as it is related significantly to lens coatings. But still they can be quite usable with the right lighting.

    Leica M8 Infrared Imaging

    The Zeiss ZM lenses show hot spot issues as well. But most are quite viable down to f/11 if some care is taken.

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    Re: Infrared and hotspots

    Quote Originally Posted by diglloyd View Post
    It is a combination of factors.
    ..
    But a large factor is the lens coatings, which is unequivocally true; see my (free) review the Zeiss ZF Prototype Lenses for Infrared.
    Hi Lloyd, Thanks for your post.

    What makes you to say that the coatings is the largest factor? Sure the transmission may be reduced a bit but uneven illumination? That is what the Zeiss transmission charts indicate.

    What are the "other" factors? Would you care to elaborate?

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Infrared and hotspots

    I find all my ASPH have hot spots on my M8. The 21 elmarit, 28 cron, 50 lux asph. The only lens that did not was my 35 cron version IV non asph. We actually have a list posted from Jim Collum in the M8 section
    Photography is all about experimentation and without it you will never learn art.

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