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Tuesday, April 12, 2011

Exposure: What does the camera see?

I post photos at two or three sites on the web. At one of those sites, Iain asked me:

William, how did you control the exposure on those shots?

Here's referring to shots like these two:

IMGP7573rd

IMGP7629rd2

The question arises because the light is very bright. I'm shooting in the direction of the sun, it's early morning, so the sun's low in the sky. Here's my response:

I don't, Iain. I let the camera does what it 'wishes' to do. One thing I will do for some shots, however, is that I will regulate just how close the sun is to the edge of a shot. I may shoot with the sun just off the edge, or slightly over the edge. And take several shots that are more or less the same except for just where I pointing with respect to the sun. You can, to some extent, control lens flare by just how close you edge the lens toward the sun.

But then, most of these shots aren't directed such that that's a consideration. I'm shooting generally toward the East, and that's where the sun is at that time of day, but the lens is generally 10, 15, 30 or more degrees away from the sun.

Now, I do have to do some photoshopping. The shots tend to be yellowish to orangish just out of the camera, but the sky may not have been like that at all. It may have been more whitish or light bluish. So I have to decide what to do. Do I keep the yellowish-orangish cast or do I back off from it? I'll often try several versions. Some very interesting this will show up in Photoshop by using Image > Ajustments > Auto Levels, Auto Color, or Equalize. I almost always fade the results of whatever Photoshop gives me in that way. And, of course, I'll use the various options in combination with one another.

I wouldn't say I do a lot of adjusting in Photoshop. But I certainly some. And I generally do more with these intense light shots than I do with 'regular' shots.

One general principle is to try to get something your eye might have seen directly. But there are problems with that. If I'm shooting close to the sun, or even into it, then I'm taking a shot that the eye can't look at for more than split second without some form of protection. So what's the scene REALLY look like? Does it have a real appearance? Otherwise, the eye is constantly adjusting as you scan the scene and compensating for variations in light flux. What you're looking at 'naturally' is always a 'composite' of several glimpses, each at a different focal point in the scene. The eye adjusts its 'settings' for each glimpse. Thus the overall scene looks well-lit in a way that's impossible for just about any optical system.

The fact is, the sense in which the camera records just what's there is, of course, straight-forward physics and engineering. But what the eye and visual system do are not straight-forward physics and engineering. Something more subtle's going on. The relationship between these two – what the camera registers and what the eye-brain sees – that is subtle as well. And is subject of manipulation and regulation through image processing.

ADDENDUM: 1) When you shoot into the light, every bit of dust in your camera's optical path is likely to show up in the photograph, magnified. My camera happens to be a tad dusty at the moment, so I had to touch-up those dust spots in Photoshop. 2) I've been doing this for awhile and so have developed a feel for what I can get away with. 

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