What is exposure compensation - my first posting

[markjass]

Just trying to work my way around my camera a Canon Powershot G16. This is my first camera that is not a point and shoot. What is exposure compensation how and when do you know when to use it. I can get my head around under and over exposure. So I take a picture and say it is over exposed, why use exposure compensation rather than shutter speed or f stop? is it about not wanting to change the depth of field or? How many clicks up or down?

Thanks

[RichardTaylor]

Welcome to the forums.

Have a look at the last section of this tutorial, here on CIC.

https://www.cambridgeincolour.com/tu...a-metering.htm

[Colin Southern]

Hi Mark,

Normally before you take a photo the camera will meter the scene and come up with what it THINKS is the right exposure. Depending on the mode your camera is in it may choose all 3 variable (shutter speed, aperture, and ISO) or if you have it in a particular mode (typically Av mode where you select the aperture for DoF control) then it'll select the other two variables.

Camera metering follows certain rules; often the result is good, but certain types of scene will throw it off considerably -- and for those times you need to use Exposure Compensation ("EC").

Trying to compensate yourself by changing things like aperture only works if you're in manual mode where you're choosing the variables; if you change the aperture in an automatic mode (eg Av mode) the camera will simply change one or both other parameters "the other way" so the exposure that the sensor sees ends up effectively being the same.

Hope this helps.

[Mike Buckley]

why use exposure compensation rather than shutter speed or f stop?

You could use either method. Another alternative is to change the ISO.

Perhaps the biggest difference between a DSLR and a point-and-shoot camera is that the DSLR often provides many methods of accomplishing the same look. You have already come upon a good example of that. As you continue to take advantage of more and more capabilities of your camera, you will come upon many more.

[Manfred M]

Just to did a bit deeper into the explanations; there are two different types of light meters; an incident light meter, i.e. one that measures the light that is falling on a subject and a reflective light meter, i.e. one that measures the light reflecting off a subject. These are separate hand-held devices and generally used in portraiture work, especially in studios work.

The more common type of light meter is the reflective light meter, which is the type that built into your cameras. As mentioned, it is used to measure an "average" scene, and if the scene is too far off average, it gives readings that cause exposure issues. Typical examples where we see these meters fail are snow scenes or white sandy beaches, night time shooting or trying to take a picture of a bird or airplane that is flying, where the sky is the background. Because the light meter is built to assume an average scene, the snow or sky shots will be underexposed and will look dark when compared to what we actually see, while the night scene will look brighter than what we see.

Better cameras have an exposure compensation control that lets you brighten scenes that come out to dark and darken scenes that come out too light. Unfortunately, there is no way of using a set of rules or formulas to determine the appropriate amount of exposure compensation. Experience certainly helps, but bracketing your shots (i.e. changing the exposure compensation and taking more than one shot) is a good place to start.

Here things get a bit counter-intuitive; for a light scene, one generally has to increase exposure (as your camera has a tendency to underexpose these) and a dark scene needs reduced exposure (as your camera will tend to overexpose thes.

[chauncey]

Just to did a bit deeper into the explanations

Manfred...going to that depth with a neophyte just might make him pitch the camera.
I gave up on trying to learn exposure compensation years ago. A whole slew of images, under various conditions, will eventually point one in the right direction.
Richards link is a decent starting point.

[rpcrowe]

Of course, everyone above is correct. If you are using any of the automatic exposure modes (Av aperture priority, Tv shutter speed priority, P programmed exposure or A full automatic) the camera is locked into what it considers the best exposure. The camera is not always correct, especially as mentioned when you are shooting extremes like a white cat in the snow or a black cat in a coal bin, or when you are trying for the correct exposure of your subject against a background that is considerably darker or lighter than the subject. In this case you will need to add or subtract exposure.

"So I take a picture and say it is over exposed, why use exposure compensation rather than shutter speed or f stop?" The problem with trying to increase the total exposure by adjusting the shutter speed or f/stop or even ISO; is that when you change one variable the other(s) will change...

Say you were shooting outdoors on a bright sunny day with using an ISO of 100 and your camera was giving you an exposure of 1/100 second at f/16 and you were getting under exposed (dark images):

If you increased your aperture to f/11 (allowing twice the amount of light) the camera would choose a shutter speed of 1/200 second and you would get correspondingly under exposed images.

If you slowed your shutter speed to 1/50 second (allowing twice the amount of light) the camera would correspondingly select f/22 and you would still get underexposed imagery.

If you increased your ISO to 200 (twice the sensitivity) your camera would select 1/200 @ f/16 or 1/100 @ f/22 and the same thing would happen...

If you wanted to increase/decrease the exposure, selecting an exposure compensation of + (to increase) or - (to decrease) would be the way to go. Which of the parameters would be increased or decreased would depend on how the camera was set up (which exposure method you were using)...

Exposure Compensation is usually talked about in measured in EV or Exposure Value. We normally talk about our exposure in stops (whether or not the aperture is actually changed). One EV is the same as one stop of exposure.

Please remember that the above only holds true for automatic or semi automatic exposure. When shooting with manual exposure any increase or decrease of one of the three parameters is independent of the other parameters and will cause an increase or decrease in the total exposure package.

[nimitzbenedicto]

Simple and easy to understand.

Thanks

Of course, everyone above is correct. If you are using any of the automatic exposure modes (Av aperture priority, Tv shutter speed priority, P programmed exposure or A full automatic) the camera is locked into what it considers the best exposure. The camera is not always correct, especially as mentioned when you are shooting extremes like a white cat in the snow or a black cat in a coal bin, or when you are trying for the correct exposure of your subject against a background that is considerably darker or lighter than the subject. In this case you will need to add or subtract exposure.

"So I take a picture and say it is over exposed, why use exposure compensation rather than shutter speed or f stop?" The problem with trying to increase the total exposure by adjusting the shutter speed or f/stop or even ISO; is that when you change one variable the other(s) will change...

Say you were shooting outdoors on a bright sunny day with using an ISO of 100 and your camera was giving you an exposure of 1/100 second at f/16 and you were getting under exposed (dark images):

If you increased your aperture to f/11 (allowing twice the amount of light) the camera would choose a shutter speed of 1/200 second and you would get correspondingly under exposed images.

If you slowed your shutter speed to 1/50 second (allowing twice the amount of light) the camera would correspondingly select f/22 and you would still get underexposed imagery.

If you increased your ISO to 200 (twice the sensitivity) your camera would select 1/200 @ f/16 or 1/100 @ f/22 and the same thing would happen...

If you wanted to increase/decrease the exposure, selecting an exposure compensation of + (to increase) or - (to decrease) would be the way to go. Which of the parameters would be increased or decreased would depend on how the camera was set up (which exposure method you were using)...

Exposure Compensation is usually talked about in measured in EV or Exposure Value. We normally talk about our exposure in stops (whether or not the aperture is actually changed). One EV is the same as one stop of exposure.

Please remember that the above only holds true for automatic or semi automatic exposure. When shooting with manual exposure any increase or decrease of one of the three parameters is independent of the other parameters and will cause an increase or decrease in the total exposure package.

[Manfred M]

Manfred...going to that depth with a neophyte just might make him pitch the camera.
I gave up on trying to learn exposure compensation years ago. A whole slew of images, under various conditions, will eventually point one in the right direction.
Richards link is a decent starting point.

That really depends on the neophyte; I had a similar explanation when I was a neophyte and had no issues with the level of detail.

I had a converstation with a photographic neophyte (regarding how a flash works) who is a PhD physicist and we got into what was happening as photons were emitted when electrons changed orbitals. It all depends on the neopyte's background and interests. I'd rather give too much detail, than not enough.

[Mike Buckley]

Manfred...going to that depth with a neophyte just might make him pitch the camera.

If that's the case, just imagine how much worse the neophyte's reaction will be upon reading the first few pages of the camera's manual. By the time I get to page 5 of mine, it lists 65 parts and 63 of them can be seen without removing the camera cap.

[rpcrowe]

Manfred wrote: "Unfortunately, there is no way of using a set of rules or formulas to determine the appropriate amount of exposure compensation. Experience certainly helps, but bracketing your shots (i.e. changing the exposure compensation and taking more than one shot) is a good place to start."

I totally agree auto exposure bracketing is a great way to get a handle on exposure in all its variables...

With all Canon DSLR cameras and certain selected models of other brand DSLR cameras, selecting auto exposure bracketing AND burst mode will allow you to shoot at least three auto exposure bracketed frames every time you press the shutter button. The camera will then cease firing until the next time that you press the shutter button. Additionally, you can select the order in which the bracketed shots will be captured. I prefer to have the shot with the least exposure first, followed by the shot a the meter reads and then the shot at more exposure than the meter reads. Default is to have the shot as the meter read first.

You can in Canon cameras (I don't know about other brands) combine exposure compensation with auto exposure bracketing. When doing night shots of cityscapes, I will choose AEB at one EV increments combined with a -1 EV Exposure Compensation. This produces three shots with one shot as the meter reads, one shot at 1-stop less than the meter reading and one shot at 2- stops less than the meter reading.

Since over exposure is the bane of most night shots, this technique will almost certainly provide at least one shot that is well exposed and you can often, if desired, combine the three shots into an HDR composite image. This can be done especially, if the camera is tripod mounted or solidly supported some other way...

[RichardTaylor]

On any camera with a live histogram (like some Canon G series, I do own a G11) the amount of exposure compensation needed is relatively easy.
Just activate the histogram on and watch it as you adjust the exposure compensation dial.
In shutter priority the aperture will change, and in aperture priority the shutter speed will change.
You do know how to read a histogram and how to decide what is important or not (like bright light sources in a night scene)

If shooting in manual exposure just use the histogram as guide when adjusting the ISO, Aperture, and shutter speed.

[Stagecoach]

Mark (?), welcome to CiC.

In the least amount of words................

Exposure Compensation is a variable adjustment available to the user to 'bias' the output by increasing or decreasing the output value of the cameras light metering system.

Grahame

[jcuknz]

I have had exposure compensation for some time now with different cameras and never bothered to learn how to use it becuase I learnt about photography long before digital came on the scene with these inventions but I would suggest that the reason to use EC is becuase it is a simple knob which you can quickly rotate [ mine is anyway] one way or the other to make the changes suggested when the camera gets an incorrect reading off the scene as suggested above.

As if if you are to use EC or not very much depends on the camera and I have only seen Gs from afar but would ask "how easy is it to adjust aperture/shutter compared to using the EC knob?" Only you can provide that answer which is based on your preference and how you relate to the camera.

A side note on the G cameras ... they are an oddball design which does not fit into the usual classes such a P&S--Bridge--- Mirrorless-- DSLR. Being a sort of top of the line flagship for Canon in the small sensor field and in the right hands capable of excellent results with every model since I saw the G2 way back.

[markjass]

Thank you for your comments and help. I have began to get my head around it. I am a great reader around a subject. Technical posts do not bother me as long as I can find articles/postings that are written at a more basic level and read these at first. They just require a bit of thought and rereading. The only think that I find frustrating is jargon or abbreviations. At work I discourage the use of these as they can lead to confusion and it can be argued that they are exclusive.

[Colin Southern]

Thank you for your comments and help. I have began to get my head around it. I am a great reader around a subject. Technical posts do not bother me as long as I can find articles/postings that are written at a more basic level and read these at first. They just require a bit of thought and rereading. The only think that I find frustrating is jargon or abbreviations. At work I discourage the use of these as they can lead to confusion and it can be argued that they are exclusive.

You're welcome Mark.

In summery, just think of it as being a "manual override" over what the camera suggests. Unfortunately, we have a lot of abbreviations in photography -- if you're not sure what one is just ask. Case in points; you'll often come across EC for Exposure Compensation and FEC for Flash Exposure Compensation.