CHG_CANON Loc: the Windy City

Agreed, where I define 'underexposed' as muddy (soft) and noisy (grainy) PP adjustments to an image purposefully underexposed in a false fear of blowing critical highlights when slightly exposing to the right vs the 0-mark of the camera.

rehess Loc: South Bend, Indiana, USA

Exactly - you want to avoid 'bleaching' out areas.
With negative film that meant avoiding underexposure.
With slide film and digital that meant/means avoiding overexposures.

With Kodachrome I learned to underexposure white New England churches and similar structures, because exposing according to the meter would wash away the markings on and between boards; unfortunately, that would leave me with a very deep blue sky and deep green grass. Today, I can use the same techniques with digital, then gently raise the left side of the curve to 'fix' the darker colors.

Ysarex Loc: St. Louis

But the OP didn't ask about false fears. Ultimately it's a setup question; which mistake is better? The question assumes that you are screwing up. You're trying to say don't make a mistake. But that's not what the OP is asking. The OP is asking pick one:

1. Blown highlights
2. Noisy mushy shadows.
3. There is no option three.

Joe

Ysarex Loc: St. Louis

STOP.

Define: for SOOC JPEG (OP's choice):

1. What constitutes overexposure.
2. What constitutes underexposure.

Joe

rehess Loc: South Bend, Indiana, USA

Yes, I understood the OP to be asking which side to 'favor' since often you know the exact answer only when you get home.

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

Slight is the operative word. Either way, if the error is slight you will be able to fix the problem. But slight underexposure may need more help with noise and contrast in the shadows. I prefer slight overexposure, as long as important highlights still have some detail in them after adjusting. It's all relative. Shooting raw will provide a little extra headroom on both ends.

burkphoto Loc: High Point, NC

There really isn’t one, once you factor in scene dynamic range and ISO...

selmslie Loc: Fernandina Beach, FL, USA

If in doubt, bracket. Nobody is going to confiscate your camera. After doing this for a while the OP can answer his own question.

ggenova64

Under Exposure. but try to get proper exposure in Camera. results in less photo processing.

MagicMark

I usually get the exposure exactly right but if for some reason I can't then I underexpose by 1 or 2 tenths of a stop. I never overexpose the shot, not even by 1 tenth of a stop. Why? Because you lose details in the highlights and your color starts to diminish and, of course, you also lose some of the dynamic range. See image. I shot this in studio and although I often have my subject turn one shoulder to the camera, I had this subject turn both shoulders parallel with the camera. In my opinion I would like this image more if I had feathered the light upwards more but, alas, my little studio has a moderate amount of floor space but the ceiling is low (7 feet Yikes!). I usually have to put my subject in a chair or on a stool so I can get my key high enough.

Canisdirus

I always underexpose my images.....
You can bring back details from the shadows fairly easily, unlike overexposed areas.
Plus, you can isolate a subject in broad daylight sometimes.... like this.

(Download)

SuperflyTNT Loc: Manassas VA

Although really with slides it was definitely more important to nail the exposure.

jcboy3

Slightly overexposed will have slightly better dynamic range and noise performance. But that assumes that the image is not overexposed to the point where highlights are blown. And that assumes that the aperture is not too large that DOF is sacrificed, or that the shutter speed is too slow that the image suffers from motion blur. And if the overexposure is simply due to ISO setting, then since most sensors are ISO invariant (for the most part), then it doesn't matter much at all.

Slightly under or over exposed is easy to fix in post editing.

However, if the image is grossly over or under exposed (highlights blown or shadows crushed), then I would opt to process the under exposed image. And that is because the brighter part of the image is usually what is critical, and it will be acceptable in the underexposed image but blown out in the overexposed image.

Finally, if you have problems with getting proper exposure, then learn to bracket exposures and pick the proper exposure later.

scubadoc Loc: Sarasota, FL

Depending on how many FPS your camera can shoot, and whether or not you are using a speed light with a relatively long recycle time, I bracket most all my shots, using the histogram to find the “best” exposure to start with. 1/3 or 1/2 step bracketing should almost always nail the correct exposure.

camerapapi Loc: Miami, Fl.

Before modern digital cameras all we had was a hand held meter and eventually meters became incorporated into the cameras. I remember when Nikon introduced the center weighted metering that photographers received with lots of enthusiasm. Then spot metering to make our meter readings more precise but the latter required and still requires experience on the part of the photographer for best results. Exposure errors have always plagued the photographer specially when shooting slide film but today with digital things have turned 180 degrees around because we have a histogram and instant feedback as a guide.

It is hard to argue that underexposure with digital does better with exposure compensation than trying to fix a clipped highlight. The main principle when exposing with digital is to make sure that important highlights are not overexposed so metering for those important highlights is most important. Opening shadows poses no problems except that in many cases the ugly face of noise will show up. By the way, noise is not always objectionable but that I will not discuss today.

So, regarding your question, it is better with digital to err on underexposure than to have clipped (overexposed) highlights.