Exposure Compensation

musicaleCA

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Edit: I think Bitter here just illustrated the virtues of trusting our histograms.

I haven't used histograms yet. One thing at a time :)

Ahaha. Fair enough. But I would suggest you put that on the list of things to do next; a histogram can really be a life-saver sometimes.
 

Henry Peach

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I understand from reading that some camera light meters just don't get the exposure right and compensation is needed.

The camera always gets it right. It's a dumb machine that does exactly the same thing every time: it tries to make the world middle gray tone. If the world was a perfect mix of tones this would work great, but there are some parts of the world that are brighter or darker. The photographer must make the decision as to whether the scene before them is best represented by an exposure that goes for middle gray or not. In the normal meter setting if the scene is very dark the meter is going to try to brighten it, and if the scene is very light the meter is going to try to darken it.

For instance you are at the beach or in the snow or shooting a bride in white. On it's own the meter wants to make all of those things gray, which would mean underexposing; you have to dial in +1 or so comp/flash comp so that it isn't fooled by all the brightness.

Going the other way, if the scene in front of you is black earth or a dark bar or a groom in black you have to advise the meter not to overexpose (once again trying to make the scene mid gray), by dialing in -1 (or so) comp/flash comp.
 
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Crosby

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I understand from reading that some camera light meters just don't get the exposure right and compensation is needed.

The camera always gets it right. It's a dumb machine that does exactly the same thing every time: it tries to make the world middle gray tone. If the world was a perfect mix of tones this would work great, but there are some parts of the world that are brighter or darker. The photographer must make the decision as to whether the scene before them is best represented by an exposure that goes for middle gray or not. In the normal meter setting if the scene is very dark the meter is going to try to brighten it, and if the scene is very light the meter is going to try to darken it.

For instance you are at the beach or in the snow or shooting a bride in white. On it's own the meter wants to make all of those things gray, which would mean underexposing; you have to dial in +1 or so comp/flash comp so that it isn't fooled by all the brightness.

Going the other way, if the scene in front of you is black earth or a dark bar or a groom in black you have to advise the meter not to overexpose (once again trying to make the scene mid gray), by dialing in -1 (or so) comp/flash comp.

Thanks Henry and everyone else, this seems to be a good topic for everyone. I'm at work so I'll have to duck and check back later.
 
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Its not always a good idea to slightly underexpose, though it is an inherent habit of mine too, coming from a background of shooting a lot of slide film.

There are those who say that with digital it's better to overexpose slightly. And it makes a whole lot of sense when you look at the reasoning and the facts. You'll enjoy reading this: Expose Right

Otherwise, because the camera's light meter is calibrated to read 18%, or mid gray, it tends to underexpose bright scenes and overexpose darker scenes. These are the times when you want to consciously and carefully compensate, i.e. slightly overexposing a bright scene (such as a snowy landscape), and slightly underexposing a dark scene, or subject.

Good post, Thanks Rich. I've been shooting underexposed because it looks warmer and more comfortable but I still post process so I might as well save more info by slightly overexposing.

I have to admit that some of that article was a bit over my head, but I'll get there some day... hopefully.;)
 

Bitter Jeweler

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Edit: I think Bitter here just illustrated the virtues of trusting our histograms.

I haven't used histograms yet. One thing at a time :)

Ahaha. Fair enough. But I would suggest you put that on the list of things to do next; a histogram can really be a life-saver sometimes.

OK, I started reading and playing. Well first I had to figure out how to get the histogram on my camera. It will only show it after the pic is taken.

I have done some playing around while reading about how it works. I took a pic of this tree. I initially felt that the first image below, looked more like what I saw, The second image I just let Photoshop do AutoLevels. Side by side I am not sure. I lean to the first one though. This was shot just after sunset, I did nothing in post except auto levels in the second image.

To me, the first one matches the sundown overcast/rainy light, and the second looks more like a brighter day. Was I right in thinking in low light, I wanted more info on the left side of the histogram to keep more detail in the dark aread? Is my goal, using the histogram, to try to get even(ish) data across the board? An example in one of the links posted here, the author shot a snowy tree scene, and exposed so that nearly all the data was on the right side of the graph.

I will keep reading and testing, I am actually finding this interesting, and no longer "afraid" of it.
*note, these were shot on a tripod, and I was trying various ISO and Aperture values (Ap Priority), and this was the least oof image of them all. The wind seemed dead calm, but my front porch is "bouncy", so I tried mirror lock up, MF, timer, so I could step away and try to stand perfectly still. Still the images aren't that sharp, but thats probably more because I was at 250mm on a cheap lense, right?

#A
IMG_A.jpg


#B
IMG_B.jpg


EXIF.jpg


Histo.jpg
 
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Well first I had to figure out how to get the histogram on my camera. It will only show it after the pic is taken.

True, I don't know of any camera that shows a live view histogram. All it tells you is the exposure level of the picture. Extreme right is blown out and extreme left is complete black.

Was I right in thinking in low light, I wanted more info on the left side of the histogram to keep more detail in the dark aread?.

Not really, the left side of the histogram just says the picture is dark rather than light. Its up to you if the picture looks right or good and consequently the histogram is shifted to the left. I've read some that say you should slightly overexpose and pull back in post processing to keep detail because there is more information in the right side of the histogram. Don't ask me to explain that! That is one of the things that was over my head, and still is...:er:

Is my goal, using the histogram, to try to get even(ish) data across the board?

An even spread across the board would mean that there are some very dark areas, complete black, shown on the histogram as touching the left 'wall' or side and some complete white or blown areas shown as touching the far right wall or side. The vertical range tells you how strong or intense that particular part is. The Histogram is only a guide to give you an idea of the exposure. I use it mainly to check for blown areas.

Also, the link RICH placed in his reply says that you really need an RGB histogram for color digital pics. Apparently some colors can be blown and you won't know it if you are only using the gray scale histogram. (if that is what it is called.)
 

DScience

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I almost always shoot in manual. Often times I am shooting during the mid day sun, and my max shutter speed is 1/4,000. With a f1.4 lens, it's not uncommon that my max shutter speed is not fast enough to get a correct exposure, and so I put my ISO on it's lowest setting, and sometimes it's still not properly exposed, then i'll use my last resort, the exposure compensation. :)
 

Steph

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I almost always shoot in manual. Often times I am shooting during the mid day sun, and my max shutter speed is 1/4,000. With a f1.4 lens, it's not uncommon that my max shutter speed is not fast enough to get a correct exposure, and so I put my ISO on it's lowest setting, and sometimes it's still not properly exposed, then i'll use my last resort, the exposure compensation. :)

This does not really make sense or maybe I am missing something. If you shoot in manual mode there is no point in using exposure compensation (you usually use exposure compensation if you are unhappy about the camera's decision in auto modes). If you get over-exposure at 1/4000 (fastest shutter speed) and f/1.4, just stop down the lens. No need for exposure compensation.
 

NateS

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(my camera only compensates in 1/3rds)

Not sure what you have, but there's usually an option to change it to 1/2 stop increments via custom function.


Personally, I don't use it much. I cases where I would want to use it, I just go to M and do it manually.

I am the same way. I'll either let the camera have control (aperture priority or whatever) or I will take over full control. If I don't like what the camera is doing then I just take over completely.
 

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