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Thread: Exposure Compensation

  1. #21
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    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    Agree. But can I say that with the setting that I got using aperture or shutter priority mode, I can use manual mode to tweak it +/-EV, using shutter speed for Av mode, and using aperture for Tv mode..So I can also says that exposure compensation is not necessary for manual mode?
    can say that, but you need to know what you are doing

  2. #22

    Default Re: Exposure Compensation

    Let me try to make it simple - if I could.

    Exposure compensation is a devise to allow one to make exposure adjustment over or under what the camera meters. Meaning, you had, by choice, allowed the camera to make metering decisions for you using a variety of metering mechanisms - such as centre-weighted metering, matrix metering or evaluative metering, to name a few. And now you suspect that the metering will be incorrect, and you want to make "compensation" to reduce or increase exposure.

    Whether you are using aperture priority or shutter priority is a separate issue, and depends on whether aperture or shutter speed is more important. Or even program or automatic mode.

    Whether there is -1, -2/3, -1/2, -1/3. +1/3, +1/2, +2/3, +1, etc is again another issue. This only allow you to decide on the decremental or incremental adjustment you want to have over the camera's metering "decision".

    There are different types of "manual cameras". Some have aperture priority built-in, some maybe with shutter and aperture priority built in.

    Some totally manual cameras have no metering built in at all, and will have to depend on an external light meter.

    But most manual (meaning with no aperture or shutter priority built-in) SLRs and rangefinders will have a metering system built-in. In such cameras, the exposure will be determined solely by the photographer with the assistance of the metering values given by the built in meter. There is NO exposure compensation mechanisms.

    Let me give some examples.

    1 My Leica R6, is a totally manual camera with a "big-spot" or some may call a "centre-weighted" metering. When I use this camera, having set the ISO, I decide on an important area to meter. This may be the shadows or the the highlights. Here it is important to know a little of the "zone system". Let me say that I meter the shadows. Knowing that the meter will give what is called the zone 5, I will proceed to "reduce" exposure by one to two stops, because if I do not, there might be too much exposure.

    2 My Contax 645. I often use my Contax 645 in manual mode. So I meter the scene exactly the same way I use my Leica R6. However, sometimes I use aperture priority mode - and set the metering to a "matrix/evaluative" type of metering. Most of the time the exposure will be OK. But occasionally there might be strong backlight. Under such circumstances, I usually change to manual metering. Or if I still wish to use aperture-priority metering, I will set the exposure compensation to +2 or even more. Basically, I am telling the camera "hey, Use your meter - but on top of what your meter says, give two or more stops".

    3 My Canon 1V. Sometimes I set my camera to progam mode when I am really lazy - and set the metering to "evaluative mode". Again, most of the time the exposure will be OK. But again, in tricky situations, I will direct the camera to make exposure compensation by decreasing exposure or increasing exposure using the exposure compensation device.

    Needless to say, in my opinion, when I use my camera in the totally manual mode, my exposures are always better than when I rely on the camera's "What-you-call' metering system with or without exposure compensation - because in totally manual mode, I know exactly how much light I am giving to where I want it.

  3. #23
    Senior Member creampuff's Avatar
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    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    Yes agree. But with current technology..aperture and shutter speed settings and even ISO settings comes in a third stop..so is it still necessary for exposure compensation?
    Yes I believe there is still a need for exposure compensation to be in 1/3 stop increments. It may not be much but it is sometimes the case where the effect of a 1/2 stop increments is too obvious.

    What is the "correct exposure" for any given situation? When cameras determine the exposure, it's calibrated to a value based on the reading off an 18% grey card. Whether one's camera is fully manual, in aperture priority, shutter priority or programmed, if the exposure for a given scene is say 1/125 sec at f8, the camera meter reading should be that. Obviously the meter can be "fooled" or thrown off by extreme lighting conditions to give either an over exposed or under exposed shot. So obviously there are many occasions where one needs to make exposure compensation to override what the camera's meter suggests.

    Exposure compensation in 1/3 EV is necessary especially if one shoots with slide film which have a narrow exposure latitude. It is a common practice to underexpose slide film by 1/3 stop to increase colour saturation. So if one were using ISO 100, one could shoot at ISO 100 with -1/3 EV compensation or just set ISO to 125. In B&W, I used to overexpose and under develop the film as a matter of course. I could use Kodak Tri-X (rated at ISO 400) at ISO 200 and adjust development time accodingly to get a less contrasty image.

  4. #24
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    Default Re: Exposure Compensation

    Quote Originally Posted by student
    Let me try to make it simple - if I could.

    Exposure compensation is a devise to allow one to make exposure adjustment over or under what the camera meters. Meaning, you had, by choice, allowed the camera to make metering decisions for you using a variety of metering mechanisms - such as centre-weighted metering, matrix metering or evaluative metering, to name a few. And now you suspect that the metering will be incorrect, and you want to make "compensation" to reduce or increase exposure.

    Whether you are using aperture priority or shutter priority is a separate issue, and depends on whether aperture or shutter speed is more important. Or even program or automatic mode.

    Whether there is -1, -2/3, -1/2, -1/3. +1/3, +1/2, +2/3, +1, etc is again another issue. This only allow you to decide on the decremental or incremental adjustment you want to have over the camera's metering "decision".

    There are different types of "manual cameras". Some have aperture priority built-in, some maybe with shutter and aperture priority built in.

    Some totally manual cameras have no metering built in at all, and will have to depend on an external light meter.

    But most manual (meaning with no aperture or shutter priority built-in) SLRs and rangefinders will have a metering system built-in. In such cameras, the exposure will be determined solely by the photographer with the assistance of the metering values given by the built in meter. There is NO exposure compensation mechanisms.

    Let me give some examples.

    1 My Leica R6, is a totally manual camera with a "big-spot" or some may call a "centre-weighted" metering. When I use this camera, having set the ISO, I decide on an important area to meter. This may be the shadows or the the highlights. Here it is important to know a little of the "zone system". Let me say that I meter the shadows. Knowing that the meter will give what is called the zone 5, I will proceed to "reduce" exposure by one to two stops, because if I do not, there might be too much exposure.

    2 My Contax 645. I often use my Contax 645 in manual mode. So I meter the scene exactly the same way I use my Leica R6. However, sometimes I use aperture priority mode - and set the metering to a "matrix/evaluative" type of metering. Most of the time the exposure will be OK. But occasionally there might be strong backlight. Under such circumstances, I usually change to manual metering. Or if I still wish to use aperture-priority metering, I will set the exposure compensation to +2 or even more. Basically, I am telling the camera "hey, Use your meter - but on top of what your meter says, give two or more stops".

    3 My Canon 1V. Sometimes I set my camera to progam mode when I am really lazy - and set the metering to "evaluative mode". Again, most of the time the exposure will be OK. But again, in tricky situations, I will direct the camera to make exposure compensation by decreasing exposure or increasing exposure using the exposure compensation device.

    Needless to say, in my opinion, when I use my camera in the totally manual mode, my exposures are always better than when I rely on the camera's "What-you-call' metering system with or without exposure compensation - because in totally manual mode, I know exactly how much light I am giving to where I want it.
    Thank you student. Your explaination is very comprehensive.

    So exposure compensation is tweaking of the metering system in order to give the exposure you desire. Hence, exposure compensation is not necessary if shooting in full manual mode, because this tweaking can be done manually by setting to the desired shutter speed or aperture.

    So does it mean.
    In Av mode f/5.6, shutter speed is 1/125 metered by the camera.
    And I want to -0.7EV, then I think aperture is not so important, I can also change the aperture to f/7.1

    In Tv mode 1/125, aperture is f/5.6 metered by the camera.
    And I want to -0.7EV, then I think shutter speed is not so important, I can also change the aperture to 1/200
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  5. #25
    Senior Member creampuff's Avatar
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    Default Re: Exposure Compensation

    Quote Originally Posted by ExplorerZ
    if at f5.6, 1/125 and f7.1, 1/125 is not equivalent. f7.1, 1/125 will give you -1.3EV since the aperture is 2/3stop slower than at f5.6. the same goes for f5.6, 1/200. (1/200 is 2/3stop faster which in terms give you lesser exposure)
    1/125 to 1/200 sec is not -1.3EV but -0.7EV.
    If it was -1.3EV it would be 1/320 sec.

  6. #26

    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    So exposure compensation is tweaking of the metering system in order to give the exposure you desire. Hence, exposure compensation is not necessary if shooting in full manual mode, because this tweaking can be done manually by setting to the desired shutter speed or aperture.
    This is correct.

    Quote Originally Posted by blazer_workz
    So does it mean.
    In Av mode f/5.6, shutter speed is 1/125 metered by the camera.
    And I want to -0.7EV, then I think aperture is not so important, I can also change the aperture to f/7.1

    In Tv mode 1/125, aperture is f/5.6 metered by the camera.
    And I want to -0.7EV, then I think shutter speed is not so important, I can also change the aperture to 1/200

    Please see creampuff's explanation in post #28.

    But I think that in situations where lighting is tricky (especially with strong backlight), it is better to use manual mode, because it is difficult to know exactly how much compensation to apply.
    Last edited by student; 28th August 2006 at 12:13 PM.

  7. #27
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    Default Re: Exposure Compensation

    Quote Originally Posted by creampuff
    1/125 to 1/200 sec is not -1.3EV but -0.7EV.
    If it was -1.3EV it would be 1/320 sec.
    oopz, must be thinking of something else

  8. #28
    Senior Member creampuff's Avatar
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    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    Thank you student. Your explaination is very comprehensive.

    So exposure compensation is tweaking of the metering system in order to give the exposure you desire. Hence, exposure compensation is not necessary if shooting in full manual mode, because this tweaking can be done manually by setting to the desired shutter speed or aperture.

    So does it mean.
    In Av mode f/5.6, shutter speed is 1/125 metered by the camera.
    And I want to -0.7EV, then I think aperture is not so important, I can also change the aperture to f/7.1

    In Tv mode 1/125, aperture is f/5.6 metered by the camera.
    And I want to -0.7EV, then I think shutter speed is not so important, I can also change the aperture to 1/200
    In metered manual one doesn't really need exposure compensation as the parameters of aperture and shutter speed are determined by the photographer. The camera's meter reading serves merely as a guide to the optimum exposure.

    However in your example in aperture and shutter priority, in changing the selected aperture or shutter speed the camera will merely compensate but you'll get the same exposure. That's not exposure compensation.

    By your example, f5.6 at 1/125 works out to EV12. If you set your camera to f7.1 in aperture priority mode, the camera will still expose at EV12 (f7.1 at 1/80 sec).
    Likewise if in shutter priority mode, if you change to 1/200 sec, if the camera measures exposure at EV12, it will compensate the aperture to f4.5.

    If you set exposure compensation to -0.7EV, you are telling the camera to override the camera's recommended exposure of EV12 (f5.6 at 1//125 sec) to EV12.7, or a 2/3 underexposure.

  9. #29

    Default Re: Exposure Compensation

    Quote Originally Posted by creampuff
    However in your example in aperture and shutter priority, in changing the selected aperture or shutter speed the camera will merely compensate but you'll get the same exposure. That's not exposure compensation.

    By your example, f5.6 at 1/125 works out to EV12. If you set your camera to f7.1 in aperture priority mode, the camera will still expose at EV12 (f7.1 at 1/80 sec).
    Likewise if in shutter priority mode, if you change to 1/200 sec, if the camera measures exposure at EV12, it will compensate the aperture to f4.5.

    If you set exposure compensation to -0.7EV, you are telling the camera to override the camera's recommended exposure of EV12 (f5.6 at 1//125 sec) to EV12.7, or a 2/3 underexposure.
    Thank you!

    What was I thinking? You corrected my mistakes in #26. I will change that.

  10. #30
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    Default Re: Exposure Compensation

    Quote Originally Posted by creampuff
    In metered manual one doesn't really need exposure compensation as the parameters of aperture and shutter speed are determined by the photographer. The camera's meter reading serves merely as a guide to the optimum exposure.

    However in your example in aperture and shutter priority, in changing the selected aperture or shutter speed the camera will merely compensate but you'll get the same exposure. That's not exposure compensation.

    By your example, f5.6 at 1/125 works out to EV12. If you set your camera to f7.1 in aperture priority mode, the camera will still expose at EV12 (f7.1 at 1/80 sec).
    Likewise if in shutter priority mode, if you change to 1/200 sec, if the camera measures exposure at EV12, it will compensate the aperture to f4.5.

    If you set exposure compensation to -0.7EV, you are telling the camera to override the camera's recommended exposure of EV12 (f5.6 at 1//125 sec) to EV12.7, or a 2/3 underexposure.
    Ok..thank you. I got what u mean here.

    Because in Av or Tv even though if we tweak the aperture or shutter speed respectively, the metering system used is still fixed at 0EV compensation..hence by changing aperture by -0.7EV at Av mode the shutter will be auto corrected..

    So can I also say that if in manual mode. Assuming my metering marking stays in the middle marker at f5.6, 1/125 with 0EV compensation. I can compensate -0.7EV by stopping down my marker 2 steps to the right, by changing aperture to f/7.1, assuming each marking is +/-0.3EV. And if I use -0.7EV exposure compensation on the camera body, I will have to achieve the marking in the middle, by changing the aperture or shutter speed?

    +3 +2 +1 0 -1 -2 -3
    :..:..:..|..:..:..:
    Last edited by blazer_workz; 28th August 2006 at 01:17 PM.
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  11. #31
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    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    Ok..thank you. I got what u mean here.

    Because in Av or Tv even though if we tweak the aperture or shutter speed respectively, the metering system used is still fixed at 0EV compensation..hence by changing aperture by -0.7EV at Av mode the shutter will be auto corrected..

    So can I also say that if in manual mode. Assuming my metering marking stays in the middle marker at f5.6, 1/125 with 0EV compensation. I can compensate -0.7EV by stopping down my marker 2 steps to the right, by changing aperture to f/7.1, assuming each marking is +/-0.3EV. And if I use -0.7EV exposure compensation on the camera body, I will have to achieve the marking in the middle, by changing the aperture or shutter speed?

    +3 +2 +1 0 -1 -2 -3
    :..:..:..|..:..:..:
    yes. like what i said, the way of input is slightly different but end result are the same.

  12. #32
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    Default Re: Exposure Compensation

    Thank you to all who have contributed. A lesson on exposure compensation learnt. Thanks!
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  13. #33

    Default Re: Exposure Compensation

    Quote Originally Posted by blazer_workz
    Agree. But can I say that with the setting that I got using aperture or shutter priority mode, I can use manual mode to tweak it +/-EV, using shutter speed for Av mode, and using aperture for Tv mode..So I can also says that exposure compensation is not necessary for manual mode?
    Exposure compensation only affects the metering. It has nothing to do with you choosing the shutter speed you want to use. It just bluffs the camera that there is more light or less light that what is actually available so that the meter can tell the camera the shutter speed and/or the aperture to use, for example, in P, A, and S modes. In the fully manual mode, the meter reading given to you by the camera would be skewed by the amount of compensation you put in. Hence, it only affects the information given to you but not what you eventually dial in as the shutter speed or aperture.

  14. #34
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    Default Re: Exposure Compensation

    For Q2, in manual mode, you cannot use Exposure Compensation....its not available. the reason is, you are in control of the Shutter speed and aperture. Do you own setting for compensation.....

    For Q3, Mechanical Manual cam change exposure by changing the shutter speed or aperture. If both not feasible, change the film to a faster/slow film (higher/lower ISO # film).

    Hope these are ok for you. In digital world, the exposure compensation is just an automated program to do the calculation for you...just automated, the principles are still the same.

    Quote Originally Posted by blazer_workz

    I still don't get it..kind of confused. I will re-phrase my questions.

    Q1.) Is exposure compensation equivalent to tweaking the aperture or shutter speed in steps of a third stop depending on what you have set?
    e.g. -0.7EV (-2/3 stop) exposure compensation:
    In Av mode f/5.6,1/125 -> f/5.6,1/200
    In Tv mode f/5.6,1/125 -> f/7.1,1/125
    In P or M mode f/5.6,1/125 -> f5.6,1/200 or f/7.1,1/125 or f/6.3,1/160

    Q2.) So if I shoot in manual mode: to get -0.7EV
    I can just select the necessary combination to drop by -0.7EV and not needing to set the exposure compensation value?

    Q3.) How does the old type of cameras achieve exposure compensation?
    Aperture is fixed by aperture ring
    Shutter speed is fixed mechanically
    ISO is fixed by film loaded into it


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