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  1. #1
    BetterSense's Avatar
    Join Date
    Aug 2008
    Location
    North Carolina
    Shooter
    35mm
    Posts
    2,872

    Where to place IR filter in the optical path

    I basically have a camera, and I want to take the IR-blocking filter from a digital camera sensor, and use it to filter out all IR from the image-forming light. Since I'm making an extreme small-angle spotmeter, image sharpness and flare matter. My question is, does it matter, in regards to image quality, flare, and IR-blockage effectiveness, where I put the filter in the optical path? Digital cameras put the filter right over top of the CMOS sensor, but is there a reason for this? Would putting the filter several mm away from the image plane, or even right behind (or in front of) the lens, be better in terms of contrast, sharpness, flare, or IR blocking effectiveness?
    f/22 and be there.

  2. #2

    Join Date
    Jan 2006
    Shooter
    Multi Format
    Posts
    905
    why not just use a hot mirror filter? smaller sizes are available relatively inexpensively. Some earlier digicams (as well as the Leica) put it on the lens, so I would say that it really doesn't matter where in the optical chain you put it.
    Last edited by epatsellis; 08-11-2010 at 01:39 PM. Click to view previous post history.



 

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