Exposure Compensation question

[m_h20]

<p>I have a Nikon D90, and I was wondering what the difference between using exposure compensation and adjusting the shutter or aperture...for example, if I am in aperture priority mode and I want to change the EV to a (-) value to make the exposure darker, is this the same as increasing the shutter speed by rotating the dial? If so, when should I use EV compensation and when should I manually change the shutter speed when shooting in A mode? Thanks!</p>

[mendel_leisk]

<p>If you're Aperture Priority mode and change your shutter speed, you're not changing exposure. You change the shutter speed, the camera will follow suite and adjust the aperture. The net result will be (roughly) the same amount of light coming through, albeit via a different combination of shutter/aperture.</p>

<p>On the other hand, if you use exposure compensation, both aperture and shutter speed will be adjusted by the camera, depending on the exposure compensation you've set.</p>

[CoryAmmerman]

<p>As Mendel said, if you're in one of the priority modes and you adjust either the aperture or the shutter speed, the camera will adjust the other to keep the same amount of light hitting the sensor according to what the meter "thinks" is right. By using exposure compensation, you are basically telling the meter that you want more or less light, depending on what compensation you set. This comes in handy when you are in a situation where you know that the meter will most likely give you an incorrect reading, such as when you have composed a picture with a lot sky in the frame and you know that this will cause the subject to be underexposed. By dialing in a +1 or +2 compensation the meter will adjust the exposure so that the subject is correctly exposed, but the sky might be blown out a bit. </p>

<p>Personally, if I use exposure compensation, I tend to do things the other way around. On an overcast day, for example, I usually dial in -1/3 or -1 compensation to maintain detail in the sky. Then I lighten the subject in post processing. I rarely ever use + compensation because I don't want to run the risk of blowing the highlights.</p>

[tommyinca]

<p>"If I am in aperture priority (A) mode and I want to change the EV to a -(1) value to make the exposure (1 stop) darker, is this the same as increasing the shutter speed by rotating the dial?"</p>

<p>Lets say you are currently at f4 and the shutter speed is at 1/125 second and you are metering in A mode. If you then set exposure comp to -1, the camera will increase the shutter speed to 1/250, there by the picture will be one stop darker. You can also achieve the same -1 EV (one stop under) by setting both the aperture and shutter to f4 and 1/250 using the manual mode, manually. The different is that, if you use exposure compensation, when you change aperture, camera will follow by adjusting the shutter again. Verse, if you use manual mode, you have to remember to meter again and apply the one stop under manually.</p>

<p>BTW: If you are at aperture priority your can't change the shutter speed via the shutter control dial directly.</p>

[lachaine]

<p>Exposure compensation is the same as adjusting the meter in the camera to be more or less sensitive, if you could do that.</p>

<p>In Tv or AV modes, when you change one, the other one will be also changed by the camera to keep the same exposure as before - so that's not exposure compensation. For example, if you close down aperture by one stop, say from 8 to 11, that's one stop. So, the camera will simply go ahead and slow the shutter speed correspondingly by one stop the other way. You end up with different aperture and shutter speed than before, but still the exact same exposure. In that mode, if you want the camera to underexpose by one stop, you have to tell it by setting -1 exposure compensation.</p>

<p>I would recommend using the camera in full manual mode first, to get a good understanding of shutter speed and aperture relationships. In manual mode, you don't need automatic exposure compensation from the meter, since you are choosing the exposure yourself. If you want to under or overexpose, you just do it.</p>

[kerry_grim]

<p>The easiest way to under or overexpose is to use manual and like Pierre said, you just do it. Generally I will choose my shutter speed first, then set the aperture. Or, often I will take a reading toward a neutral area in manual, then recompose the shot.</p>

<p>I would imagine someone came up with the idea of automatic exposure compensation to make things easier. It doesn't! Just additional buttons or menus to look at.</p>

[dbcooper]

<blockquote>

<p>"when should I use EV compensation and when should I manually change the shutter speed when shooting in A mode?"</p>

</blockquote>

<p>You cannot change the shutter speed in Aperture-priority mode. In Aperture-priority mode, you select the aperture, and the camera selects the shutter speed based on the camera's light meter reading. If you change the aperture setting, the camera will change the shutter speed accordingly to agree with the camera's light meter (the overall exposure remains unchanged). If you want the image lighter or darker than what the camera's meter is giving you, use Exposure Compensation.</p>

[alfredo orihuela]

<p> Right on Cooper! your just about the only person to nail it. <br>

Thats it, why use expo-comp? for all auto settings; because the camera determines the setting for that frame based on the light meeter, so, the way to "help" the camera's judgement for the correct exposure is by altering it's light meter(in form of exposure compensation); or if maybe one needs reassurance(when in manual) on seeing the exposure settings dead on centre knowing that such settings are corresponding to the given compensation alteration.<br>

This is to say that if you know for sure how much a particular frame would need compensating Eg.±1/3 or ±2... then making the adjustments by using exposure compensation is always far more accurate than merely "speculating" manually alone. Not as fun though... ; )<br>

Try, try, try. Good luck!</p>

[iliafarniev]

<p>The meaning and use of EC is simple. If your camera is in any AUTO mode and you want to shut the motive in average different brightness compared to <em>standard grey card</em>, say scene with much of bright white snow, you can override AUTO exposure in accordance with your judgement without going into MANUAL mode.</p>

<p>In case of bright snow: if you shoot AUTO with 0 EC you get darkish, dull snow but if you set EC to +1eV or +2eV you get briliant snow. Correspondently, in case of coal pile compensate -1eV to -2eV if you want blacks black.</p>

<p>If your AUTO mode is on apperture priority EC value will deal with shutter speed only.</p>