When to Use Exposure Compensation

[bleeblu]

Amateur here.

I understand the basics of aperture, shutter speed and ISO. I know that a stop (correct term?) of one of them in either direction will either allow more or less light into your exposure. And if you increase a stop in aperture and decrease one in ISO, technically, it will be the same image. Am I right?

I hope I haven't lost anyone, yet.

So I'm considering buying the Finepix X10. I noticed the two dials on the top of the camera are for shooting modes and exposure compensation. I know what exposure compensation does to an image. I think. It, essentially, allows your exposure to be brighter or darker. So here comes the questions.

Why would you want to change the exposure compensation when you can alter the aperture, shutter speed or ISO to alter the image the way you want it to? And when would I want to change the compensation rather than the aperture, shutter speed or ISO?

It has to be important to have as a dial on the Finepix X10. I just don't see how it's more important than, say, maybe a dial for the shutter speed. Something you would be playing around with a lot more.

Can anyone clear this up for me, please?

 

[radiorickm]

First off, you are correct that you can alter the exposure when in MANUAL mode by changing either the ISO, Shutter speed, or the Aperture.

The exposure compensation dial works with the camera in any of the "semi-automatic" modes, such as Program, Shutter Priotity (TV), or Aperture Priority (AV).
When shooting in these modes, the EC dial allows you to "change" the exposure to your liking.

Here is an example of how it would work:
If in shutter mode, you pick 1/125, and the camera picks F8 to go along with it.
When you look at the picture, you decide that it is under exposed.
So you move the shutter down to 1/60 to let in more light: problem is, the camera will just pick f11 to put the exposure back to the same.
So, you use the EC dial to tell the camera that you want (what ever amount you choose on the dial) the exposure changed.

I hope this makes sense. there are many times that the light meter is fooled, or is just plain wrong. This EC dial allows you to deal with it while remaining in one of the auto modes.

Good luck

 

[dots]

Instead of the shutterspeed the in-camera meter would otherwise select for that aperture, you are instructing the camera to 'compensate' with a faster or slower shutterspeed...equating to +/-EV you dial-in.

 

[joealcantar]

Keep it simple, that microchip has thousands of possibilties in it programmed so it gets everything right. In certain light conditions the camera does not read things right and one has to give it a little help in the thinking process. So we tweak to get our desired results.
-
Shoot well, Joe

 

[bleeblu]

So most people use EC when in a priority mode and not full manual?

 

[dots]

Not in manual mode.

 

[Overread36]

Here is how I'd explain it;

In the semi automatic modes such as aperture or shutter priority mode you give the camera control over one setting, whilst you retain control over the other two. Exposure compensation is used to tell the camera to under or overexpose the photo, but using the setting it has control over based upon the meter reading.

So for example if you are in aperture priority mode and have set an aperture of f8 and an ISO of 100 and then metered the scene.
The camera might give 1/800sec as the shutter speed.

However, past experience in such lighting conditions or creative control might well mean that you know that the meter is being fooled* and that you want to adjust the exposure. Therefore you dial in to tell the camera to overexpose the scene by one stop. This results in the camera now selecting 1/400sec as the shutter speed (the aperture and ISO remain the same as they are in your control).


Now if you are in manual mode most cameras don't have exposure compensation enabled here, and instead you have to adjust the settings to over or underexpose as needed. Some, eg Nikon, however do show exposure compensation; but instead of changing the settings it biases the meter - so the 0 middle point is no longer 0, but might be an under or overexposed value; so whilst you're still lining the meter point up on the 0 mark it is now representing an under or overexposed value.



* a good example would be shooting a snowy scene where the meter will try to make the snow grey and thus underexposes.

 

[bleeblu]

Thank you. This makes much more sense. Do people usually shoot in a priority mode over manual?

 

[Overread36]

It really depends what and how you shoot - some people never leave manual and others never leave priority modes. In general many of the people I know will typically shoot in aperture priority mode; whilst those who shoot with flash dominated lighting (eg studios) almost always shoot in full manual (since the camera can't meter for the flashlight that is going to be added and thus is not able to give good results with the priority modes).

In the end it really comes down to what works best for you - so learn the priority modes and manual mode and then you can make the choice on what you find works best in the situations you shoot in.

 

[Derrel]

I use EC mostly when photographing PEOPLE who are in front of dark backgrounds....usually dialing in some Minus compensation to prevent over-exposure. In backlighted situations, I will often dial in some over-exposure if I want to see more detail in the shadows and a brighter background. THe only mode I typically use EC in is Aperture-priority Automatic, when I am setting the f/stop I want for background control, and am allowing the camera's meter to pick an appropriate shutter speed.

 

[BlairWright]

I use EC mostly when photographing PEOPLE who are in front of dark backgrounds....usually dialing in some Minus compensation to prevent over-exposure. In backlighted situations, I will often dial in some over-exposure if I want to see more detail in the shadows and a brighter background. THe only mode I typically use EC in is Aperture-priority Automatic, when I am setting the f/stop I want for background control, and am allowing the camera's meter to pick an appropriate shutter speed.

Same thing here. The other thing EV comp allows is 1/3 step increments. It's really good (in manual also) to correct blown highlights where many times you don't need a full stop.