Differences Between Low-Key and Underexposed

I know this has been discussed before but the terminology has been bugging me so I just wanted to clarify this. I looked up some definitions too but it's still not quite what I'm looking for.

Often in the critique threads, I'll see people disagreeing about whether an image is "low-key" or just plain underexposed. I guess I've always thought of it as a low-key image being one with predominantly dark tones but with some "correct" exposure in areas of the photos. I also think in terms of studio lighting when I'm picturing low key and high key lighting, even though I know the principles applies regardless of what the light source is.

How about just shots taken in dark room, like at a bar or a restaurant with low ambient lighting? If I take a picture that is very dark overall, but shows the scene as it appears to someone in the room, would that be a "correctly exposed low-key" shot or just "underexposed". If it's not a correct exposure, then how would I determine what the "correct" exposure is?

I'm not asking this in terms of what makes a good image or what to strive for when shooting, I'm just asking in terms of clarifying the terminology.

This might not be right, but to me low key is a picture that has softer contrast and colors that are less saturated or vibrant, but everything including shadows are properly exposed. Not the same with an underexposed picture where the shadows will be clipped resulting in a loss of detail.

A lowkey image has most of the tones in the bottom register. The subect itelf is properly exposed, with a portrait for example, the skintones must be properly rendered. Underexposing the skin tones will lead to an underexposed image.

Quite often, the lighting is quite harsh with well defined shadows. Also, there must be parts of the image that are white to give the image some lift and contrast.

When shooting a lowkey, have your histogram leaning towards the left.

The best way I can describe a lowkey is a model in black clothes/dark hair aginst a black background. There should be detail in the shadows, skin tones correctly rendered and some whites.

Any definitions/examples I've ever come across of those styles would be that low key is predominantly dark tonal values while high key mostly higher ones. The operative word is predominant. Also properly exposed...under or over exposure is not what makes them.

Being in the realm of studio still life photography, low or high key images are designed that way

Here are a couple

HOSTED PHOTO
please log in to view hosted photos in full size.

HOSTED PHOTO
please log in to view hosted photos in full size.

I think GtrPlyr's last sentence sums it up. Low key is a conscious choice, whereas underexposed is an unintended result. You can certainly try to pawn off an underexposed image as "low key", and if by dumb luck it works for the photograph, then you'll get away with it. The term "properly exposed" is rather subjective as it's entirely dependent upon your vision of the final photograph. If the photograph turned out as you envisioned it, then I say it's properly exposed. All else is artistic preference.

That all makes sense. I guess that's about what I had thought but I just kind of confused myself I think.

Basically, it sounds like the lighting and scene have to be designed in a specific manner to create it in order to really call it low-key, you can't just underexpose a scene and try to say that it's low-key. And as pointed out, that doesn't mean that you can never get a good photo by underexposing, it just means that it's not true lowkey

elogical wrote in post #12788318
That all makes sense. I guess that's about what I had thought but I just kind of confused myself I think.

Basically, it sounds like the lighting and scene have to be designed in a specific manner to create it in order to really call it low-key, you can't just underexpose a scene and try to say that it's low-key. And as pointed out, that doesn't mean that you can never get a good photo by underexposing, it just means that it's not true lowkey

Not to throw a monkey wrench at you but try and get away from thinking underexposed/overexpos​ed. Think or plan ahead what you'd be exposing for if your intention is to create a low or high key image.
Remember, low or high key simply means either a predominance of low or high tonal values respectively.

Take the above photo of the welder for example. If I've preconceived a shot like that as wanting to create a low key image, then my exposure...my proper exposure... would be for tonality and texture in the highlights.
As far as dynamic range goes, in that I want a low key image, I now know much of the lower tones are going to be pushed towards underexposure.

But, this is what is planned! Its not accidentally underexposing then printing it down! Its knowing what film/photography does, how to manipulate it and get the result you pre-visualized.

Low key doesn't necessarily mean large areas of black either. Imagine a color image (we've all probably seen this particular photo 'motif') of, say, a snowy landscape at nightfall with also a small cottage in the scene.
The overall shot has a dark and subdued blue cast and then there are the solitary bright orange warm tones coming through the cottages windows.

GtrPlyr wrote in post #12788525
Take the above photo of the welder for example. If I've preconceived a shot like that as wanting to create a low key image, then my exposure...my proper exposure... would be for tonality and texture in the highlights.
As far as dynamic range goes, in that I want a low key image, I now know much of the lower tones are going to be pushed towards underexposure.

The problems with exposing for the highlights in an image like this is, is the brightness range. If I would have metered for the actual oxycutting (he was oxy cutting not welding) the main subject, the cutter would have been grossly underexposed.

Now,, this was shot on Tri-X 400 film many years ago.Tri-X, if exposed and developed carefully has an incredibly long brightness range,, up to 6 to 7 stops. Even with Tri-X, a scene like this it would be absolutely impossible to get both detail in the highlights and detail in the shadows.. Looking at the image, a brightness range of 10- 12 stops would be present.. The sparks and highlights were so bright. Also,the sparks etc were the only source of illumination.

What I did was, expose for the shadows and decreased my exposure by -1EV, then pulled the development back by about 30%-40% in the soup. This gave me some detail in the shadows, but still blew out the highlights, absolutely nothing I could do about it. Also, it's impossible to lift the shadows by development alone.

I'd love to try this again, but this time digitally.. I would sill have the same problems with the dynamic range of the scene. I would still expose for the shadows at -1EV and allow he highlights to blow out to gain some exposure in the guy's face.

Just to add,, if you check out the EXIF in the image,, you'll see it was imaged by a 20D.. What I did was, I re-photographed the original 16-20 inch print with a 20D and Tamron SP 90mm f/2.8 Macro..

yogestee wrote in post #12789076
The problems with exposing for the highlights in an image like this is, is the brightness range. If I would have metered for the actual oxycutting (he was oxy cutting not welding) the main subject, the cutter would have been grossly underexposed.

Now,, this was shot on Tri-X 400 film many years ago.Tri-X, if exposed and developed carefully has an incredibly long brightness range,, up to 6 to 7 stops. Even with Tri-X, a scene like this it would be absolutely impossible to get both detail in the highlights and detail in the shadows.. Looking at the image, a brightness range of 10- 12 stops would be present.. The sparks and highlights were so bright. Also,the sparks etc were the only source of illumination.

What I did was, expose for the shadows and decreased my exposure by -1EV, then pulled the development back by about 30%-40% in the soup. This gave me some detail in the shadows, but still blew out the highlights, absolutely nothing I could do about it. Also, it's impossible to lift the shadows by development alone.

Very cool! I was thinking about explaining film/development with the OP but then I thought, what if he doesn't know film, plus my post would start going very long.

Btw, I used to do a lot of b&w film night shooting. I got into using rodinal something like double the normal dilution ratio of 1:100 if I recall. (its been a long time). Managed to get detail in the darkest areas without blowing the highlights.

Sure, the torch flame and sparks would be treated as pure specular highlights. What I meant was more of exposing for the facial highlights in this case.