oldtool2 Loc: South Jersey

An interesting question with a lot of answers. If you error on the side of overexposing and you have white in your photo you take a chance of blowing out the details. If you have white you are better off to underexpose and then bring out the detail in your post processing. Once you blow your details out by overexposing you can never recover them. Blown details are just that, gone forever. I try to never overexpose if possible but I do a lot of nature photography, especially birds, and they tend to have a lot of white or very light colors.

It is true that by overexposing you will cut down on some noise. There are a lot of programs out there that can help you eliminate noise but there's not many programs, if any, that can recover blown details.

Jim D

ole sarg Loc: south florida

This one really caught me off guard. I was going to suggest that when exposing never wear a red rain coat!

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Actually, it is not really considered overexposure - you are maximizing and optimizing exposure as much as you can, without "over" exposing. Once you learn your camera's characteristics, you get a sense for the upper limit on the histogram, and how that translates to a raw file's highlight clipping threshold.

GregWCIL Loc: Illinois

There is a practical side of this discussion. First you have to recognize there is only so much light. Thus if you add exposure you have to subtract something else. One choice is to use a higher ISO but that defeats what you just did in terms of graininess. The second is aperture - probably your best bet but isn't ideal is some situations. The third is shutter speed which can lead to other problems.

For example, a week ago I was shooting monkeys (ok, photographing) in dense jungle in Panama. I has my ISO cranked up, aperture wide open and still had trouble keeping shutter speed high enough. There was simply no room to get more exposure even though I needed it for the black monkeys backlit by mid-day sun.

If you are doing a static landscape shot from tripod, then you have much more freedom. Often you can use a longer shutter speed so you can keep your ISO in the optimum range. Then the ettr concept becomes easier to use.

jrushphoto Loc: Flint, MI

Absolutely true, exposing correctly to start does trump all, but even Ansel Adams knew you can't always get all areas of an image exposed correctly in-camera. With his incredible Zone System he "exposed for the shadows and developed (modern day post processing) for the highlights." He did pretty well with that and it still holds true in todays digital world.

marki3rd Loc: Columbus, Indiana

You are confused. Exposing to the right brightens the image, not darkens the image.

studavis

Shoot HDR

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Actually the opposite is true. You needed to record minimum shadow detail, if that was important to the image - below a threshold, which was different for different films, developers, development times and temperatures - you simply could not record enough information above the fog and base density of a film emulsion. Highlights would have tons of information but often it was too dense on the negative to be of any use, unless you "burned in" the highlights by exposing them longer to the enlarger's light than the rest of the image. Adjusting the parameters of your developer - formula, concentration, temperature and developing time - you could control the final result in terms of contrast and ability to render shadow detail while not allowing the highlights to "block up."

Digital is the reverse. If you overexpose an image where the highlights are "blown" there is no getting them back. On the other side of the histogram, your threshold is a lot lower, so you have more room to work with, particularly if you shoot raw - there is just more information recorded in the shadows, even if you underexpose them as much as two stops.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

That is not necessarily true - ETTR just means that you concern yourself with getting as much information as possible, without overexposing important highlights. You focus on the right side of the histogram - not the middle. If you have high contrast, your unprocessed image will be darker - beach and snow scenes, sunset/sunrise, etc. If you have low contrast (4-6 stops), what you say will be true - by increasing exposure to move the middle of the histogram to the right, your resulting image will be brighter.

DaveHam Loc: Reading UK

The exposure on a digital camera should be weighted to the light / fully exposed side while avoiding clipping.

The reason is the way a sensor captures information. Half the total data is captured in the most exposed stop, then half of what is left is captured in the next stop, and so on. So if you have a sensor capable of a five stop range, 50% of the data is in the light stop zone, and less than 5% in the darkest stop area.

Post processing requires data - by exposing towards the light area you retain more data and can produce better images.

MtnMan Loc: ID

By definition there are no programs that can recover blown details. Blown means there are no details to recover.

DavidPine Loc: Fredericksburg, TX

Absolutely correct. ETTR doesn't mean you blow out the highlights. The histogram plays a vital role and you need to learn to read what it is telling you. I just try to get my histogram as far right as possible without blowing it out. It isn't nearly as complicated as some try to make it.

camerapapi Loc: Miami, Fl.

I am going to give you my version. Others may differ.
Overexposure with color film was alright due to the wide dynamic range of film. Overexposure with slide film was a disaster.
Digital is different to film because the image is captured by a sensor, not recorded on film. Underexposure of a subject with digital and depending on the camera may bring about noise in the dark areas. I am sure you are aware that underexposure or overexposure is not correct exposure.
Sensors are better than ever. In the beginning there was a serious problem with their sensitivity not reproducing very well overexposed areas. It was recommended then by experts to expose for the bright areas of the subject and to compensate accordingly. It was also recommended to overexpose in low light precisely to reduce the amount of noise and let me repeat it again, those old sensors showed different sensitivities to light but that to a great extent has been corrected with the new sensors.
In my case I seldom use matrix metering. I was educated using spot and center weighted metering because I know what they do and I know what I have to do to control the exposure. I also seldom look at the histogram, so confident I am with my exposure meter.
I tend to take a meter reading of the most important bright part of the subject and compensate accordingly. This way I make sure that my bright areas will be properly exposed.
Modern files allow an easy 2 stops more of light in the shadow areas without significant deterioration to the image which is easily accomplished opening the dark areas.
Correct exposure is the way to go and the histogram is there to help you.
I hope this helps you understand your concerns.

boberic Loc: Quiet Corner, Connecticut. Ex long Islander

A warning here. Don't ever expose yourself. Either over or under exposure can get you in trouble. Sorry! I just couldn't resist.

BebuLamar

ETTR is the reverse of exposing for the shadow.
Exposing for the shadow you watch your shadow make sure it has enough exposure and don't care for the highlight. You fix it in the darkroom.
ETTR you watch the highlight make sure it's not overexposed and don't care for the shadow which you can bring it up in post.