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Thread: adjusting exposure

  1. #21

    Default Re: adjusting exposure

    Quote Originally Posted by aungzawwin View Post
    hi,
    i'm still confused

    in M mode, once aperture, shutter speed and ISO are set, and if camera meter supposed to be showing -.....l.....+ (no bias at all), adjusting EV compensation can change the exposure?

    if i need -EV, i'd adjust faster shutter speed or smaller aperture(let's keep ISO constant); in that case the camera meter will show, say,
    -..l..l.....+

    if i'd need +EV, i'd do the opposite..

    i don't think tweaking EV to - or + will change the exposure of your final image unless you change the shutter, aperture or ISO in M mode..

    please enlighten me why there is a need of EV compensation in M mode(let's not say about using flash)..

    thanks
    My understanding is that the EV will allow you to have the effect you want without affecting the exposure. Read my other reply here
    Last edited by two200; 20th October 2009 at 04:37 PM.
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  2. #22
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    Default Re: adjusting exposure

    Quote Originally Posted by two200 View Post
    My understanding is that the EV will allow you to have the effect you want without affecting the exposure. Read my other reply...

    don't we use EV for simpler control over "exposure(brightness)" in P, S or A modes?
    can it be used to manage any form of "effects" of the image?
    thanks for the link to your post..it was about different characteristics of A or S(Tv)..right?
    but i'm looking forward to learn more about using EV function in M mode..thanks

    if i want control over DOF or something like that, i'd use P*(program shift) which also does not affect the exposure in different combination of aperture & shutter speed..
    Last edited by aungzawwin; 20th October 2009 at 06:14 PM.

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    Default Re: adjusting exposure

    Quote Originally Posted by aungzawwin View Post

    please enlighten me why there is a need of EV compensation in M mode(let's not say about using flash)..
    EV compensation in M mode is similar to shifting your ruler forward or backwards the same amount each time you measure something.

    Sometimes people want "systematic errors" such as when you measure the dimensions of a spot on your floor where you want to place some near furniture. You should be adding at least a few centimetres to your readings as allowance for some extra space so that you can place that new furniture in comfortably.

    Likewise in photography, people (me included) tend to shoot with some offset (+0.5 EV in my case) to meter such that it gives them allowance in the shadows/highlight details due to limited dynamic range (as compared to the human eye), but ultimately you decide which end to sacrifice if you have no filters in a single exposure of a over-contrasty scene. (I tend to sacrifice the highlight with 0.5EV setting)

    Actually, the answer can be inferred from the other replies already. Again, basically, it's just a matter of how you want to measure as ultimately, the control is up to you in M mode. YOU control the exposure. In the same way, YOU control the "effect".

  4. #24
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    Default Re: adjusting exposure

    Let's not forget that Exposure Compensation in Manual mode (as in offset of the exposure meter) works on Nikon, but not on Canon. Canon does not have this function, when in M mode the respective button gets a different purpose.
    Not sure about the other brands.
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    Default Re: adjusting exposure

    hmm.. i guess many are confused abt the EV compensation in M mode..

    for Av (A) mode, u set the aperture value. assuming that ISO is already fixed, that leaves the camera to decide on the shutter speed based on its meter (what it sees as a "proper exposure" for that particular scene.

    When u adjust the EV compensation either + or -, you are telling ur camera to over or underexpose the scene by that amount of stops compared to the "proper exposure" decided by the camera. this results in the adjustment of the shutter speed to match whatever exposure compensation u've set.

    Same goes for Tv (S) mode. just that the camera adjusts the aperture value for u when u provide the shutter speed and ISO of ur preference.


    However, in M mode, u set all the 3 variables that affect exposure. Aperture, shutter speed and ISO. The EV bar will tell u the difference between what u set(the 3 values determined by you), and what the camera meters.
    Eg, if it shows -1, the exposure of the resulting image captured by the settings made by you is 1 stop underexposed compared to what the camera meters as "proper exposure".


    Therefore, i don't suppose u can actually adjust the EV compensation in M mode since u are in control of all 3 settings (aperture, shutter speed, ISO).
    the bar merely shows u how is the exposure compared to what the camera "sees".


    Correct me if im wrong.
    Last edited by Fragnatic; 20th October 2009 at 10:56 PM.
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  6. #26

    Default Re: adjusting exposure

    Quote Originally Posted by aungzawwin View Post

    don't we use EV for simpler control over "exposure(brightness)" in P, S or A modes?
    can it be used to manage any form of "effects" of the image?
    thanks for the link to your post..it was about different characteristics of A or S(Tv)..right?
    but i'm looking forward to learn more about using EV function in M mode..thanks

    if i want control over DOF or something like that, i'd use P*(program shift) which also does not affect the exposure in different combination of aperture & shutter speed..
    the link is to explain the difference between exposure and effect

    Maybe put another way.
    the effect is like applying powder on the model's face. This is dependant on the tone and thickness of the colour (akin to Tv and Av). Once the application is completed the effect of the powder on the face remains the same no matter what the lighting condition is.

    Now the exposure to light is akin to changing the EV. If the lighting is brighter then the face looked brighter (+EV) with the effect (powdered face) not changed. If the lighting is poor (-EV), the face will looked darker, again without any change with the powdered face
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  7. #27
    Moderator Octarine's Avatar
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    Default Re: adjusting exposure

    Don't come to close to your camera with all that powder
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    Default Re: adjusting exposure

    Quote Originally Posted by Fragnatic View Post
    ........
    However, in M mode, u set all the 3 variables that affect exposure. Aperture, shutter speed and ISO. The EV bar will tell u the difference between what u set(the 3 values determined by you), and what the camera meters.
    Eg, if it shows -1, the exposure of the resulting image captured by the settings made by you is 1 stop underexposed compared to what the camera meters as "proper exposure".

    Therefore, i don't suppose u can actually adjust the EV compensation in M mode since u are in control of all 3 settings (aperture, shutter speed, ISO).
    the bar merely shows u how is the exposure compared to what the camera "sees".
    .................
    yes, that's what i understand about the "exposure bar" in M mode..in this case, i'm not that dumb i guess..phew!

    since i'm in control of all parameters(A, S & ISO), i can know if my exposure is "in line with" or "how much deviated" from camera's recommended(metered) exposure by seeing the exposure bar, rite?

    so, if i liked to underexpose, i'd adjust either A or S (let's keep ISO constant) so that the exposure bar will show like this -..l.......+ (-EV)

    if i want overexposure, i'd open up the A or slow down the S..rite? in such case, the EV bar will show like this..
    -.......l..+ (+EV)

    what i still don't understand is "why we want to tweak EV compensation" in M mode..we can set 0EV, -EV or +EV by adjusting several combinations of A, S or ISO..rite? so..once you have set the exposure for the scene, do you tweak EV compensation for what?

    since i read catchlights' post and thought there might be other usefulness of adjusting EV compensation after having set the exposure in M mode..


    Quote Originally Posted by catchlights View Post
    to get correct exposure, set your exposure according to the camera meter show at 0.0 when you meter the scene.

    so if you see ....|...., this is the recommended exposure setting for this scene.

    if you dial -2.0EV, the meter will show overexposed for 2.0 stop (.|...i....) at the same scene with the same exposure setting.

    and when you dial your camera shutter speed, aperture and ISO to get meter showing ....|.... again, take a shot, you will get this scene at -2.0EV exposure

    that is what you ask for, -2.0EV
    Last edited by aungzawwin; 21st October 2009 at 03:39 PM.

  9. #29
    Moderator catchlights's Avatar
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    Default Re: adjusting exposure

    I think these two parts video can help you understand better.



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  10. #30
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    Default Re: adjusting exposure

    From my D40 manual page 47 -

    "Exposure compensation is used to ...... It is available only in P, S and A modes and is most effective....."

    So EV adjustment is intended for P, S and A modes. Nikon seems to know that EV in M mode is confusing.

    If we want to use EV in M mode, just remember to adjust the camera meter to Zero as what catchlights has demonstrated.

    Is EV useful in M mode? Up to the individual really.

  11. #31

    Default Re: adjusting exposure

    No. when using M mode, u don't always adjust the meter to zero. It all depend on which part in the subject u r metering. u may need different compensation for diff. things u meter.

    Confusing?

    Ok. u must understand this: for all Digital cams, say, if u take a picture on a white object, it'll turn out greyish. Similiarly, If u shot a black subject, It'll also turn out greyish. That's where u need to compensate so that white turns out to be white & black turns out to be black. So, u only adjust the meter to zero when u meter at 'midtone' object. otherwise, u need to compensate according...

    That goes to Av/ Tv mode..
    Last edited by SamPaul; 21st October 2009 at 06:11 PM.
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  12. #32

    Default Re: adjusting exposure

    I think the confusion comes from the area that the camera actually down or up shutter to compensate according to EV instead of changing sensor power.

    Unless there is a camera that compensate by sensor, shutter speed will auto varies with EV in all modes.

    Quote Originally Posted by aungzawwin View Post
    hi,
    i'm still confused

    in M mode, once aperture, shutter speed and ISO are set, and if camera meter supposed to be showing -.....l.....+ (no bias at all), adjusting EV compensation can change the exposure?

    if i need -EV, i'd adjust faster shutter speed or smaller aperture(let's keep ISO constant); in that case the camera meter will show, say,
    -..l..l.....+

    if i'd need +EV, i'd do the opposite..

    i don't think tweaking EV to - or + will change the exposure of your final image unless you change the shutter, aperture or ISO in M mode..

    please enlighten me why there is a need of EV compensation in M mode(let's not say about using flash)..

    thanks

  13. #33

    Default Re: adjusting exposure

    Quote Originally Posted by SamPaul View Post
    No. when using M mode, u don't always adjust the meter to zero. It all depend on which part in the subject u r metering. u may need different compensation for diff. things u meter.

    Confusing?

    Ok. u must understand this: for all Digital cams, say, if u take a picture on a white object, it'll turn out greyish. Similiarly, If u shot a black subject, It'll also turn out greyish. That's where u need to compensate so that white turns out to be white & black turns out to be black. So, u only adjust the meter to zero when u meter at 'midtone' object. otherwise, u need to compensate according...

    That goes to Av/ Tv mode..
    to further illustrate this:

    Imagine u r shooting an object consisting of pure black,pure white & mid grey. U use M mode & meter at the black, u shd adjust the aperture or shutter speed setting so that the meter is -2EV (so the the black will be black & not greyish). if u meter at the white part, +2EV or grey, 0EV. You will also notice that if u meter -2EV on the black object (in M mode) then u shift to meter on the grey object, the meter will automatically move to 0EV, & to white, It'll move to +2EV.

    However, if u r using Av or Tv mode, u hv manually adjust the compensation dail according to the object u meter.

    Of course, u may not always see these three colors in your object. Hence, u need to recognize what color belongs to which zone in order to get the correct color & exposure..
    Last edited by SamPaul; 21st October 2009 at 07:04 PM.
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  14. #34
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    Default Re: adjusting exposure

    akagi07, pls excuse me for the hijack

    pls correct me if i'm wrong..

    in matrix metering mode, my EV bar(camera meter) shows 0EV when i manually expose a scene with both shadows & hilights..
    when meter for the shadow, it bias to -EV, rite? if i'm correcting it, i might blow the hilights..
    when meter for hilights, it bias to +EV..and shadow details will be lost if i corrected it..

    does it mean the blacks (in the scene) are not black-enough and whites (in the scenes) are not white-enough if i don't follow one of those metering bias?

    i expect there is no definite yes-or-no but i'd like to make sure my doubt is gone by one(or several) of your kind inputs..

    coz, i usually bias my exposure to -EV (meter directly for bright part of a scene) and lift the shadows with a little help of flash when possible..
    but i never tweak again the EV compensation when i see the EV bar mentioning that my setting is "underexposed for the scene"
    thanks

  15. #35

    Default Re: adjusting exposure

    yes feel free.. I'm listening to all comments with my eyes (learning mode)

    at the same time as well, when shooting landscape in sunset or bright background, I tried with these methods (kindly correct me if my method is wrong)

    1) take metering when focusing at the sky bright spot (half shutter), adjust till the metering balanced, set -EV to ard 2 stops on my D90 (shooting in RAW), re focus my subject in foreground, overall pic is dark. Learnt from tips that use PS to adjust the exposure in later part.

    2) take metering when focusing at the sky bright spot (half shutter), apply AE-L, still half shutter, move the focus onto my subject at foreground, shoot.

    i find opt 2 gave me no diff, pic still dark.
    Last edited by akagi07; 21st October 2009 at 10:39 PM.

  16. #36

    Default Re: adjusting exposure

    Quote Originally Posted by aungzawwin View Post
    akagi07, pls excuse me for the hijack

    pls correct me if i'm wrong..

    in matrix metering mode, my EV bar(camera meter) shows 0EV when i manually expose a scene with both shadows & hilights..
    when meter for the shadow, it bias to -EV, rite? if i'm correcting it, i might blow the hilights..
    when meter for hilights, it bias to +EV..and shadow details will be lost if i corrected it..

    does it mean the blacks (in the scene) are not black-enough and whites (in the scenes) are not white-enough if i don't follow one of those metering bias?

    i expect there is no definite yes-or-no but i'd like to make sure my doubt is gone by one(or several) of your kind inputs..

    coz, i usually bias my exposure to -EV (meter directly for bright part of a scene) and lift the shadows with a little help of flash when possible..
    but i never tweak again the EV compensation when i see the EV bar mentioning that my setting is "underexposed for the scene"
    thanks
    It is normal that when u meter for the shadow, it bias to -EV whereas highlight bias to +EV.
    The thing is -EV or +EV by how many stops is consider as 'correct' exposure? U have to understand which part of the scene u first meter for 0EV. If it's like a green field, yes, maybe 0EV but if it like metering a scene of a ski resort covering with snow, u might need to start with maybe +1.5EV..then u check by metering into, ex. a wooden hut, the meter should bias to maybe, -2/3EV. As I mentioned, u must have some ideas about some color tone, what color should falls into which meter zone.

    I once bought a CD explaining very detail on this..it's called 'Perfect Exposure' by Tim Cooper. Watch it & you'll know what I mean...
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  17. #37

    Default Re: adjusting exposure

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    eh sir, please do not spam in our forum

    back on the exposure discussion i think some camera don't allow you to EV compensate on Manual mode.

    But in anycase that can be done manually like what was mentioned.

    in metering scenes under difficult lighting situation like snow , harsh background or composition with little mid tones , compensation is needed . and like what the bros mentioned , we need to consider which part of the scene that we would to prioritise.

    i once read a book that says that there isn't a perfect exposure , but only the exposure you want to create or have. But then , this is coming from someone who has mastered his craft and definitely knows what is exposure at his fingertips heh ,

    so for ordinary folks like me , still important to know the basics
    Last edited by Dream Merchant; 8th September 2010 at 09:26 PM.
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  18. #38
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    Default Re: adjusting exposure

    Quote Originally Posted by aspenx View Post
    Likewise in photography, people (me included) tend to shoot with some offset (+0.5 EV in my case) to meter such that it gives them allowance in the shadows/highlight details due to limited dynamic range (as compared to the human eye), but ultimately you decide which end to sacrifice if you have no filters in a single exposure of a over-contrasty scene. (I tend to sacrifice the highlight with 0.5EV setting)
    In other words bro, you are "Exposing to the right"? I do that too.

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