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Any automatic metering method that minimizes highlight clipping?

Discussion in 'Panasonic Cameras' started by New Daddy, Jun 23, 2012.

  1. New Daddy

    New Daddy Mu-43 Regular

    193
    Jan 24, 2011
    I get quite a few photos from my GF1 and GH1 in which the subject's skin is blown (most often the arms) on a bright day. When the scene is of high contrast, I think this is inevitable because the automatic metering will just try to even out the entire scene to achieve 18% gray.

    But if my objective is not overall 18% gray but preventing highlight clipping - especially if the clipping is taking place on the subject's skin - is there anyway to do it automatically without resorting on the histogram?
     
  2. TDP

    TDP Guest

    If you are in a situation where you expect the camera's metering to blow out highlights, reduce your ev to -1. While the entire image will be darker, it is quite easy to pull out shadows in post processing - but it is impossible to regain areas of an image that are completely blown out.
     
  3. Warren T.

    Warren T. Mu-43 Veteran

    338
    Mar 10, 2010
    San Francisco
    You need to experiment to see what works best for you, but you can try setting metering mode to center weighted, and exposure comp to -1/3 for starters. In extreme situations adjust exposure comp increasingly until you get the desired result.
     
  4. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    Use a spot metering mode.
     
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  5. New Daddy

    New Daddy Mu-43 Regular

    193
    Jan 24, 2011
    I think -1 EV is about the right amount to dial in to avoid highlight clipping in the subject's skin.

    Now, can you somehow build this into a custom mode or scene, instead of having to dial in -1EV every time you are out in the sun?
     
  6. New Daddy

    New Daddy Mu-43 Regular

    193
    Jan 24, 2011
    Not practical. I usually put the focus on the subject's face (or eyes). I don't know why but highlight clipping usually takes place in the subject's arms.
     
  7. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    You have never heard of AEL--Auto Exposure Lock?
     
  8. meyerweb

    meyerweb Mu-43 Hall of Famer

    Sep 5, 2011
    Let me guess, you're shooting jpeg? You'll find raw gives you dramatically more headroom to recover "blown" highlights, especially if you use LR 4.

    Otherwise, yeah, what people said. Dial in a little - EC and, for extra insurance, use exposure bracketing so you get 3 pics at (for example) -1.5 stops, -1 stop, -0.5 stops).

    While it would be possible, in theory, to design the metering system to automatically reduce exposure to eliminate blown highlights, the camera can't know whether the highlight is a face or an arm that you want to retain detail in, or a light bulb that's going to be blown no matter what you do, and that you don't want to try to save.
     
  9. fin azvandi

    fin azvandi Mu-43 All-Pro

    Mar 12, 2011
    South Bend, IN
    I would also spot meter in this situation as it's faster then mashing buttons on the E-PL1. Focus on the eyes, spot meter on the arm, then recompose and shoot. Simple if you've split the focus and exposure lock onto different buttons..
     
  10. TDP

    TDP Guest

    there are a bunch of techniques to get around this. one way is to focus/AEL lock on the subject's face (and eyes, pertaining to the focus), hold the button half way down and recompose - shoot. That is often done with either center weighted or spot metering. I like doing this with people shots when there is strong back light, the result is a very high key dreamy effect.

    another way, take a few test shots in P and either have the camera bracket or bracket it yourself. note the best shot that doesn't clip, set the camera to manual and dial in the best example from your P test shots. this works great as long as your lighting doesn't change. I like doing this for night time walk around shots. the camera meter always wants to make the shots too bright. I figure out what I want, set it to M and rock on taking shots.

    or....when you see a situation where you know your camera meter is going to not give you the results you want, spin the EV up or down to trick the built in meter to give you the results you want. I like to do this when I am in P or A mode and shooting a bunch of different lighting situations. when I see one I think the camera meter is going to screw up, I spin that dial 3 clicks...then spin it back.

    there may be other ways I haven't thought of.

    I'm the wrong guy to ask if there is a custom setting function button thingie that makes any of these three things a saved setting, I don't use those things. At most, I would like an idiot reset button that sets the camera to auto everything so when I'm all set up for plan A and behind me I see Bigfoot walking hand in hand with Elvis and they stroll up to the UFO being driven by JFK I can hit the idiot reset and snap a few money-makers. My 1990s Minolta 7xi had that.....
     
  11. TDP

    TDP Guest

    Me? I only shoot RAW.

    I thought a truly blown highlight contained no data? I think I read that in some Scott Kelby book years ago.
     
  12. New Daddy

    New Daddy Mu-43 Regular

    193
    Jan 24, 2011
    Try to visualize this: You take an exploratory shot first, play back the shot to examine where highlight was blown, go back to shooting mode, get the spot metering off of the blown part (more often the arms in my case), lock the exposure, recompose, lock the focus (this time on the eyes) and then shoot.

    AEL sounds plausible on paper, but, in practice, it's not really a robust, streamlined option for the circumstances I described.
     
  13. Lawrence A.

    Lawrence A. Mu-43 All-Pro

    Mar 14, 2012
    New Mexico
    Larry
    The rule for color slides in the old days was to meter the brightest highlight in which you wanted to retain detail, then give that area +2EV. The exact number will change depending on the sensor and jpeg engine in your camera, and you'll need to experiment to see what compensation is best, but the general principle of metering for the most important highlight and compensating appropriately remains valid. Unfortunately setting one, never changing variable into your auto exposure system is not going to work. Auto exposure is a system of averages, and on average you're going to lose some if you depend on it without vigilant use of compensation. That said, I found on many of my Olympus 4/3 DSLR's -1/3 gave me the best chance during careless shooting.
     
  14. crsnydertx

    crsnydertx Mu-43 Top Veteran

    995
    Dec 31, 2010
    Houston, TX
    Chuck
    You're right - a truly blown highlight has no data. What happens at times is that one of the three channels has some data, and the RAW processing uses that channel to restore some of the lost detail. I'm sure there's a better explanation; to me, like so many aspects of digital photography and processing, it's just magic.
     
  15. jloden

    jloden Mu-43 Hall of Famer

    May 15, 2012
    Hunterdon County, NJ
    Jay
    I'll preface this by saying that I'm an inexperienced shooter, but what I've been doing in situations where I need to spot meter for a better exposure is:

    1) Select desired focus area, hit Fn button (set to AFL only) to lock in focus where I want it, and/or adjust manually if desired.
    2) Spot meter on the desired location, half press shutter to lock exposure.
    3) Re-frame shot as desired, press shutter rest of the way down.

    I've experimented a little bit more lately in switching metering modes too. It seems to offer an improved exposure for me much of the time using center-weighted metering, especially indoors. I also found that with manual focus spot metering is more useful, since there's no added worry about auto-focus re-focusing if I have to reframe.

    Other than that... i t looks like this isn't available for the GF1 and GH1 but Panasonic has since added the Intelligent Dynamic Range setting which is specifically designed to try and reduce clipped highlights and and blocked shadows. I'm not sure how effective it is as I've not really experimented with it yet but it might offer some improvement in the situation you describe.

    There should be "Intelligent Exposure" on your GH1 but from what I read it's not the same thing as the later models' Intelligent Dynamic, and doesn't do as much for blown highlights. Might be worth trying though and see if it offers any improvement for you, since you have the option available.
     
  16. CUB

    CUB Mu-43 Veteran

    275
    Apr 19, 2012

    No, it is inevitable because the scene has a range of contrast from light to dark that is greater than the camera's sensor can record.

    The ability of the camera to record a range of brightnesses is defined by the dynamic range of the sensor. Micro Four Thirds sensors generally have a more limited dynamic range than larger APS-C and full frame sensors.

    Typically an m4/3 sensor will have a dynamic range of around 10 to 10.5 stops, where each stop represents a doubling of the light level. This is several stops short of the best APS-C and full frame sensors which manage around 13.5-14 stops.

    If the scene you are shooting has a contrast of 10.5 stops or less, the m4/3 sensor will record it without blowing out the highlights or filling in the shadows. If the contrast is greater than 10.5 stops, either the highlights will blow out or the shadows will fill in, or both.

    If you shoot JPEG only, the dynamic range of the image will be even more limited, by an additional 1.0 to 1.5 stops, leaving you with only 9.0 to 9.5 stops to play with. It is unlikely that you will find many scenes with this little contrast, so it is almost inevitable that the highlights will blow out or the shadows will fill in, or both.

    Several people have suggested deliberately underexposing your shots, and that is fine as long as you don't mind the shadow detail filling in. You can always bring up the shadows in post-processing.

    But I would strongly recommend shooting JPEG+RAW and then post-processing the RAW file. This will give you 1.0 to 1.5 extra stops of dynamic range which may be all you need. If it isn't quite enough, underexpose slightly and you will find you have lost much less shadow detail than if you shot JPEG.

    Don't take my word for it - shooting both RAW and JPEG will give you a chance to compare the two and see the difference for yourself.
     
  17. New Daddy

    New Daddy Mu-43 Regular

    193
    Jan 24, 2011
    As the OP, I just wanted to make it clear that I shoot RAW. The problem I described still lingers even when shooting RAW.
     
  18. AnttiV

    AnttiV Mu-43 Regular

    91
    Apr 19, 2012
    Finland
    Considered getting a Panasonic body? Those tend to have the Panny's "iA" button, which is essentially what you described. No matter what mode/setting you are in currently, pressing that button sets the camera in full-automatic mode. (including image settings in the "iA+" mode.) Press that again and you're back wherever you left.
     
  19. MexicoMik

    MexicoMik Mu-43 Regular

    195
    Mar 19, 2012
    I have never found - in all the years they have been made - that any sort of matrix metering works satisfactorily. Center weighted is what I use 90% of the time and spot maybe 10 percent. I only use matrix-type metering when I want to be sure that NO part if the image will be properly exposed! :)

    Using center weighted, you can move the camera around and observe in the VF/screen as the "exposure" changes. When it looks like what you want, lock the exposure and recompose/shoot.

    It's important to understand that if the scene is sufficiently contrasty, it will be impossible to capture the shadows and the highlights equally well. You have to decide which is the important part of the image. Digital works almost identically to slide film so exposing for the highlights works best. You can bump up the shadows in post though if done more than just slightly, it usually results in a flat, unsatisfying image.

    Digital Raw is still not even close to covering the dynamic range of print film so expecting a current digital image to match what a $10 throw-away camera with some kodak/fuji 400 or 800 can do dynamic range-wise is unrealistic.
     
  20. jloden

    jloden Mu-43 Hall of Famer

    May 15, 2012
    Hunterdon County, NJ
    Jay
    I don't want to derail the original thread, but I'm curious - where do you find numbers for dynamic range capability of a camera? Is there a site that offers that information easily? I've had a hard time finding useful comparative data looking at D.R. for two given cameras, and I haven't found any digital cameras with a D.R. in the 13-14 range. Not sure if it depends on how it's measured or who does the measuring though.