Should this be done using image processing software like Photoshop or with the camera's built–in function?

It seems to me a program like Photoshop could use much better algorithm than what is available in the camera; or does the camera do something else before taking the image?

Note—I'm asking about standard shooting mode, with HDR (High Dynamic Range), Exposure Bracketing, ADL (Active D-Lighting) modes turned off.

Isn't the logic here the same as the logic with digital zoom, which is useful only when shooting in a compressed format as the zoom is done before compressing. Or is there something else?

Related questions:

  • 2
    \$\begingroup\$ Here you can find the answer: photo.stackexchange.com/questions/8142/why-do-it-in-camera \$\endgroup\$
    – asalamon74
    Jul 13, 2011 at 17:20
  • 1
    \$\begingroup\$ @asalamon74 - Whoa! O.O Few days ago, I asked question like this (mine), where I ask for several settings. Them moderators/members here advised me to separate them into different questions.. Noone said, that there's such(similar) question :\ I'll take a look at the other question later. But I'm not sure, that duplicates mine - as mine is specific. Anyway, thanks for the reference! \$\endgroup\$ Jul 13, 2011 at 17:26
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    \$\begingroup\$ Especially the question of exposure is adressed in the answers photo.stackexchange.com/questions/8142/why-do-it-in-camera/… and photo.stackexchange.com/questions/8142/why-do-it-in-camera/…. \$\endgroup\$
    – Leonidas
    Jul 13, 2011 at 17:41
  • 3
    \$\begingroup\$ I don't think there's a problem at all in having focused questions where the answer happens to be already there in a reply to more general question. There's also no problem with linking to those answers in comments here. Everyone is right, so let's all be happy. :) \$\endgroup\$
    – mattdm
    Jul 13, 2011 at 20:09
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    \$\begingroup\$ @Kiril: I think I actually recommended that you either search for existing answers, or, if none were available, ask new ones. I am not sure if this specific question has actually been answered, but there were a couple that you asked in your original question that we have existing topics for. \$\endgroup\$
    – jrista
    Jul 13, 2011 at 23:23

3 Answers 3


Exposure-Compensation affects how the camera takes the photo.

No matter what you do later, you cannot get what was outside of the captured dynamic range back.

So, the answer is YES and it is probably the most commonly used setting of all.

  • \$\begingroup\$ Just one more thing - does it affect a RAW photo? I guess so, but just in case.. \$\endgroup\$ Jul 14, 2011 at 9:26
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    \$\begingroup\$ Yes, it does affect RAW. Remember that exposure is basically determined by a combination of aperture, shutter speed and ISO. Therefore, unless you're shooting manually, a camera has to make decisions automatically based on what it thinks is the "correct" exposure. When faced with, say, a high contrast scene, a camera can become easily confused, so exposure compensation allows you to override what the camera thinks is a "correct" exposure. It's always better to get an exposure "right" at the time that you shoot rather than hoping that RAW contains enough data to fix it in post (it might not). \$\endgroup\$
    – Nick
    Jul 14, 2011 at 12:31
  • \$\begingroup\$ @Kiril - Yes. Refer the first sentence of my answer ;) \$\endgroup\$
    – Itai
    Jul 14, 2011 at 14:02
  • \$\begingroup\$ What do you mean by "most commonly used setting of all"? Is there some data supporting that? I read it as "most commonly fiddled", for which there are other good candidates, like focal length ("zoom" in compacts), mode, aperture, ISO. \$\endgroup\$
    – Imre
    Jul 14, 2011 at 16:18
  • \$\begingroup\$ Well, every digital cameras has EC (even my phone actually). They may not have zooms, controls over aperture (etc) and beginners do not generally know what to do with ISO. My data is based on what my photography students say and what I teach them! \$\endgroup\$
    – Itai
    Jul 14, 2011 at 17:17

Do a little experiment - set your camera to Av (or A) mode and choose an appropriate middle-of-the-road aperture for your situation, half press the shutter and look at the shutter speed - now dial in -1 stop exposure compensation and half press the shutter again - see what happened? the exposure compensation function changed the shutter speed - it's not using digital processing at all.

You can also repeat the same experiment in Tv (or S) mode and you will see the aperture change.

The exposure compensation function changes the aperture and/or shutter speed - two values controlling real physical parts inside the camera that can't be changed in post processing.

So, what is that exposure compensation slider in your raw processor? it's a feature used to add noise, sorry, I meant it's used to recover details from shadows or highlights that are blocked/blown in the jpeg but still have data in the raw or to change the brightness of the picture.

Depending on your camera it's possible there's a little or a lot of data in the raw that is outside the "jpeg range" but that data is always closer to the dynamic range limits (so it's noisy) and it's limited to what was captured (unlike the in-camera setting that changes what's captured).

Also, changing the exposure in post will have different depth of field and motion blur than using the in-camera exposure compensation - so it's entirely possible both methods will give you completely different images.


Once you've blown those highlights, or underexposed the dark corners you are never getting them back. Sure, there are some things that get blown in the JPEG version that really wasn't blown in the RAW, ad then you can get it back, but you use EC on the analogue end before the ADC, and that means that EV changes the parameters that control not only exposure, but DOF, noise and motion blur, depending on the priority mode.

Yes, I agree that EC is one of the most used settings.

ISO I normally set once and for all when I start (to get the shutter speed in the right ballpark).

Focal length can only be fiddled when I use a zoom lens, which is rare.

Aperture I set to accommodate the characteristics of the scene, and don't change that when it's just right.

But I will still be tweaking EC between each shot; it is actually the major reason why I decided to change from the rebel series to the semi pro range of Canon (with its 2 dials) because it was very annoying to press and hold +/- and use the single dial on the rebel all the time, which added stress in the long run.


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