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Automate ETTR?

Discussion in 'X-Pro2 and X-Pro1' started by theselinskiest, Feb 12, 2018.

  1. theselinskiest

    theselinskiest Member

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    Hey QQ - is there a way to set the X-Pro2 to automatically ETTR (Expose to the Right)? Sure would be handy to have a custom function for this for landscape shots
     
  2. FujiMongol

    FujiMongol Premium Member

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    Specular highlights (reflections, the sun,...) should be blown out, whereas diffuse highlights (light section of the sky) should not.
    It is not possible for a camera to make that distinction easily.
    If it was programmed to never blow out any color, many pics would end too dark and not using the dynamic range at disposal.
    Though if it was an option to switch ON or OFF, it might have use in shots without specular highlights.

    Yet menu's and possibilities are already overwhelming, it would be one more thing to consider, or loose track of and skew your pic and wondering why.
    Then again, ETTR in the offered JPG histogram is not ETTR in the according (not-offered) RAW histogram, both can differ considerably, which one would you like to see respected?

    Secondly, what histogram to respect? The balanced one (the white one) or the color one (green, blue, red)? That goes for both JPG and RAW histogram. White balance and especially the scenes available color set drives them histograms apart.
    Which one to respect to tune ETTR against?
    Automating this would be very tricky.

    2cents
     
  3. ysarex

    ysarex Premium Member

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    That is an excellent synopsis of why an automated option is not an option.

    I would only add that given the bias of the camera manufacturer to pull back from a full sensor exposure you could leave the EC control on the camera set + as a default. On my X-T2 I keep the EC set to +1 by default; I often increase it from there and almost never decrease it from there. Close as you're probably going to get.
     
  4. theselinskiest

    theselinskiest Member

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    OK, that's a fair point about specular highlights - hadn't considered that. I suppose you could make it so that it recognizes specular as a percentage of the image, but probably not a good way to make it so it's reliable and therefore would just anger people. Probably myself included.

    But, you guys are blowing my mind in other ways...

    There's different histograms? I always shoot in RAW - I hope that means I've been looking at the RAW histogram in camera.

    What bias? What do you mean "pull back from a full sensor exposure"?
     
  5. bralk

    bralk Premium Member

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    Regrettably - there is only an 8 bit jpg histogram.
    Shooting "normal" scenes in RAW without dominant light or dark areas I dial in + 2/3 ev compensation.
    (to get near the ETTR level)
     
  6. ysarex

    ysarex Premium Member

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    To a greater or lesser degree all the camera manufacturers put a little spin on their system's metering and JPEG engines to bias them away from the risk of clipping the sensor. They've got their thumb on the scale so that if you use the camera to get a good looking JPEG then the raw file for that shot is typically underexposed by 1/2 to a full stop. From their perspective it makes sense and I'd do the same if I was them. Since clipping the sensor is an unforgiving error why not hold back a little -- slight sensor underexposure is a very forgiving error.

    fuji_jpg.jpg

    That's an unedited JPEG from my X-T2. Most people would look at that and say it's overexposed -- highlights are certainly blown out. If you look at the EXIF data you'll see I had the EC at +1.67 for that shot. The raw file is textbook nailed -- the sensor is fully utilized. If I had set the camera to produce a good exposure JPEG in that scene I'd have an underexposed raw file. The camera is engineered to work that way.

    Here's an interesting related question: What's the ISO of the sensor in your camera?
     
  7. theselinskiest

    theselinskiest Member

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    this is pretty interesting - gonna have to play with more positive EC.

    as for the question - I realize that Fuji's are "ISO-less", that's one of the reasons I went with Fuji.
     
  8. ysarex

    ysarex Premium Member

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    Fuji's are not ISO-less. Some of the camera's tend more ISO-less than others but none are fully ISO-less. The new X-Trans III sensors are not ISO-less because of the dual capacitance structure. But that's beside the point. Even if the sensor's were completely ISO-less they are still light sensitive and all have a clipping threshold or full-well capacity that can be used to determine their level of light sensitivity.

    To answer that question most people would say ISO 200 which is the base ISO of the camera. But that is not the ISO of the sensor. That rating is for the output of the JPEG processor which does not have to be (and is not) the same as the sensor.
     
  9. FORUM USER

    FORUM USER Premium Member

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    No there isn't.
     
  10. theselinskiest

    theselinskiest Member

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    Please login or register to view linksat the time of writing). I don't think that ISO-less means there's no clipping threshold

    Is ISO 100 on the X-Pro2 any different than ISO 200 but slower? Based on data I've seen, I don't think it is, but your comment spurred the question.
     
  11. ysarex

    ysarex Premium Member

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    I agree, the X-Trans II sensor is as close to ISO-less as you can get. Pragmatically you can come really close to treating it that way. And absolutely ISO-less does not mean there's no clipping threshold. The fact that there is a clipping threshold does mean it's legit to label an ISO-less sensor with an ISO value -- there are real limitations to the sensor's light sensitivity.

    On the X-Pro2 ISO 100 is indeed different than ISO 200. 200 is the camera's base ISO. 100 is an extended 100. When 100 is used the camera meter will deliver more exposure to the sensor; that's a difference. The Fujix EXR processor will then process the raw file differently.
     
  12. theselinskiest

    theselinskiest Member

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    differently = better? I've seen dynamic range data to suggest it's not really better. I'd expect that if it were better you'd get a longer dynamic range, but that doesn't seem to be the case.
     
  13. ysarex

    ysarex Premium Member

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    Dynamic range data for what? The raw file? I'm not certain what if anything Fuji may be doing with the ISO 100 prior to and/or during ADC. I assume the EXR processor has to treat the raw file differently in processing.

    Better? More sensor exposure is better and less sensor exposure is less better with the one caveat that exceeding the sensor clipping threshold is very bad. In terms of extended ISO and the fact that in the JPEG above I posted the EC was set to +1.67 (ISO set to 200) what was the ISO I actually exposed at if you factor in the EC value. Can I say I exposed the sensor at ISO 64? Remember that the camera ISO values do not actually apply to the sensor.
     
  14. adamjbonn

    adamjbonn adambonn.com

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    There’s not many cameras that offer a raw histogram... iirc the first gen leica monochrom does, but not live

    When we start talking about DR modes (which we haven’t here) and pull ISO 100, a big thing to consider is how our raw software will treat the info.

    The raw file will have info embedded into it from the camera, but the raw software must read and act on that info, and not all software does this in the same way.
     
  15. lawsofphysics

    lawsofphysics Premium Member

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    How about semi-automatic?

    In terms of exposure, my goal is to maximize exposure when the shutter is open.

    To me, this means letting unimportant highlights blow out while using the longest practical shutter times and widest useful apertures.

    I only use raw files.

    For the Trans III cameras:
    • When there is ampler high to normal light conditions, use ISO 200
      • choose appropriate, practical shutter ties and, or apertures
      • ignore underexposure
      • insure the sensor is not overexposed
      • auto bracket 3 exposures
        • typically by +/- 1/3 stops; but +/- 1/2 stops can be useful in very bright light
        • usually I bracket aperture;
      • during post-production rendering
        • keep the raw file with the best highlight region rendering; delete the other two
        • render with the appropriate global brightness (a.k.a the exposure slider)
        • selectively pull (darken) highlights
        • selectively push (lighten) shadows
    • In low-light light, use ISO 800
      • except for checking for over exposure, the steps are the same
    For the Trans I and II cameras I use ISO 200 unless light levels are very low.

    In very low light I might use ISO 400. However the improvement in shadow-region signal-to-noise ratios (a.k.a. perceived shadow-region image quality) is subtle.

    Otherwise the rest is the same.

    The main advantages for are me is exposure is maximized with a minimum of effort and distraction. I only have to worry about freeing subject and camera motion, DOF and avoiding over exposure.

    The disadvantages, in general are:
    • You must optimize image rendering during post-production
    • In-camera image review is often not possible, so you have be confident of focus and composition; others can't view in-camera images
    • As with any technique, it requires practice, the more you use it, the better you become. Eventually choosing shutter time, aperture and auto-brqkitng stop size becomes second nature.
    For landscape shots life is simpler. Since landscape senses are often static, you can auto-brqacket multiple sets of 3 exposures. The parameters can be chosen such that the exposures overlap without being redundant. Of course manual bracketing multiple exposures could be simpler. In the end you still choose the best raw file and delete the others.
     
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  16. theselinskiest

    theselinskiest Member

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    thanks for the process run-through, some things to think about there.
     

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