Lenses for infa red.

Discussion in 'Native Lenses' started by Petrochemist, Mar 11, 2015.

  1. Petrochemist

    Petrochemist Mu-43 Top Veteran

    Mar 21, 2013
    N Essex, UK
    I do quite a bit of IR photography with my µ4/3 kit & have access to a spectrometer at work, so have measured the lens transmission across the available spectrum (200nm in the UV to 1100nm in IR).
    I've tabulated the data for all the lenses I've tested on an infra red dedicated forum (http://global-infrared.freeforums.net/thread/80/lens-transmission-wavelength-repost-forum) but thought the plots of the native (& c-mount) lenses might be of use to some here too.

    I suspect the short focal length lenses spread the spectrometers beam from the detector somewhat but the relative transmission should be close to being correct. (The 45-200 gave similar shapes at both ends of the focal range but lower measured transmission at the wide end).
    Most of the native lenses I tested had very significant reductions in transmission at UV & IR wavelengths - unlike my older adapted lenses, which show little or no reduction at IR wavelengths. I suspect the lens on the 9mm BCL is too small for me to get a meaningful result.
    mu4-3 lens spectra -256.gif
    Last edited: Mar 11, 2015