• JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    Here's a graphic that displays the light levels recordable at various ISOs in a camera with a base ISO of 100. It ignores read noise.

    image.png

    Comments?

    image.png

    PNG, 37.5 KB, uploaded by JimKasson 2 years ago.

  • finnanhelp_outline
    322 posts
    2 years ago

    HAND.

  • JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    Or 13, 14, or 16 bits of precision.

    That's a myth, measured with respect to full scale. I've only tested one camera with significant highlight nonlinearity before clipping, and that camera only did it at one ISO setting. I think the myth got started because of the different ways that camera's metering systems are set up.

    As I said in the OP, I'm ignoring read noise here. And precision doesn't play a part in this graphic if the ADC precision is12 bits or more, so I'm not understanding what you're getting at here.

  • SrMipanorama_fish_eye
    457 posts
    2 years ago

    I wonder if that myth was started by including highlight reconstruction, i.e., the camera’s behavior after clipping of at least one channel. I have observed different amount of highlight reconstruction potential with different cameras (Leica M), but have not looked into it in more details. Highlight recovery is a game of luck as one never knows whether color will be preserved or not. Nonetheless, it is very helpful when exposing incorrectly.

  • JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    As I understand it, highlight reconstruction is affected in the camera design mainly by the compromise matrix, and thus the CFA. But highlight reconstruction is not performed in camera, but by the raw developer.

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    Does photo diode-specific highlight headroom make sense?

  • DeletedRemoved user
    2 years ago

    Maybe ...

    kronometric.org/phot/sensor/diodeSat.gif

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    Shoulder is what I see ;)
    Even more interesting in photo-voltaic mode (used in some technical sensor applications, I use one of those to shoot welding).

  • SrMipanorama_fish_eye
    457 posts
    2 years ago

    Any highlight headroom comparison and analysis that I have seen, evaluated how clipped raw files are handled by raw developer :(.

  • finnanhelp_outline
    322 posts
    2 years ago

    HAND.

  • SrMipanorama_fish_eye
    457 posts
    2 years ago

    Can you elaborate? Jim's graphic is not related to DR, as I understand it.

  • finnanhelp_outline
    322 posts
    2 years ago

    HAND.

  • JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    With one exception at one ISO setting, all the cameras I've tested are designed so that the ADC clips before the curve above bends over far enough to be photographically useful.

  • JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    In order to relate the graphic to DR, I'd have to bring in read noise and photon noise, and also pick a SNR threshold. That would make it camera specific. I didn't want to do that. DR is full scale over mean at some threshold SNR, so you can't read DR off the graphic. What the graphic does show is the effect of ISO setting on full scale with full scale measured in lux-seconds of exposure.

    For camera-specific DR vs ISO curves, see Bill Claff's PDR charts.

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    Same here.

  • finnanhelp_outline
    322 posts
    2 years ago

    HAND.

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    "above arbitrary base".

  • finnanhelp_outline
    322 posts
    2 years ago

    HAND.