Auto-exposure

Since Phil took the bait, here's a simple test you can do to find out whether automation is homogenizing your photographs. Take one of your photos and open it in Photoshop. Then do this:

Filter > Blur > Average

Image > Mode > Grayscale

Now use the Eyedropper tool to sample any point in the image.

Finally, look in the Color Palette and see what percentage of gray is "average" for your picture.

If the answer is about 50%, you probably used auto-exposure. Phil likes aperture-priority automation. He justifies its use this way:

"I don't think the automation in the camera makes a great deal of difference. Once you have decided what you want to take a picture of, compose the shot and focus on the topic of interest there are only two real choices you can make on a camera; aperture and shutter speed. And the choice of one strongly constrains the other"

This is true - if you want the average density of your photo to be 50% gray. Your camera wants the average density of your photo to be 50% gray, because that's the average for a photo with a "full range of tones" more or less evenly distributed (for example, a picture of a human subject outdoors in the daytime on a grass lawn.)

Here's a photo I took at Reed's late last year. I saw some shadows on the wall in a dark corner and thought they looked interesting in a brooding, film-noirish way. The corner was very dark, and I wanted the picture to look dark, the way my eye saw it. If you run the Photoshop action I've described above on this picture, you'll see that its average gray percentage is 95%.

When I took the picture, I knew that the normal exposure for ambient light in Reed's is about 1/60 of a second at f/2 on 400 speed film. In dark corners, there's much less light. I shot this picture (manually) at 1/30 at f/2. If I'd used aperture-priority automation at f/2 (assuming my camera did that, which it doesn't), the camera would have noticed that the wall wasn't lit, and it would have set a shutter speed of either 1/4 or 1/2 second - resulting in a picture with an average gray percentage of about 50%, which would have looked like this:

I like my picture a lot better than the one an automatic exposure meter would have generated. I could have tricked my F-100's auto-exposure system into producing the picture I wanted by setting "exposure compensation" to tell the F-100 that the scene was supposed to be dark. But then what good is the automation? I already know the scene is dark, and it's no harder to set the exposure values manually than it is to set exposure compensation manually - so all the automation does is make it more likely that I'll get lazy and end up with a bad picture.

Automation won't hurt your "average" pictures (photographs of people in daylight, for example), because those are the pictures it was designed to produce. It is much more likely to hurt dark or light pictures, or anything else "out of the ordinary".

Open up a bunch of your pictures and try the Photoshop experiment I've described above. If your highest gray density is only 10% higher than your lowest, turning off autoexposure will probably improve your photography.

How I Take A Picture 1: Take Responsibility

I have a Nikon F-100. It's a great camera. It has lots of advanced functions. It winds the film onto the takeup spool as soon as I close the camera back. It reads the ISO sensitivity of the film off the film cassette and sets it automatically. When it gets to the end of the roll, it automatically rewinds the film. I can set it to leave the film leader out of the cassette, or to wind the film all the way into the cassette with no leader sticking out. The F-100 has aperture-priority and shutter-priority automatic exposure, and a program mode, and a "flexible program" mode, which lets me change the aperture or the shutter speed and automatically compsenates for the exposure difference by changing the setting I haven't touched. The F-100 has spot metering, center-weighted average metering, and "matrix metering". It has autofocus. It has TTL auto-flash with distance sensing, which measures the light as it hits the film and closes the shutter when just exactly the right amount of light has gotten in. It has exposure compensation and flash exposure compensation. It shoots 5 frames a second. It fits my hand like a glove.

I never use it.

I got tired of turning all those features off.

I turned them off because I realized after a while that my first step in taking a picture should be to take responsibility. Taking responsibility was hard with the F-100. It was always whispering to me. It would say things like "The light just changed. I could handle that for you - why don't you just let me set the exposure while you worry about more important things?" or "It's really dark in here. Why don't you just let me add a little flash?" And since I'm lazy and weak, I'd sometimes give in and let the F-100 take some of the responsibility I should have been taking.

The F-100 handled those responsibilities beautifully. It made far fewer mistakes than I did.

You're wondering why I wanted to take responsibilities away from a machine which handled them better than I did. Here's why: because the F-100 was a slut. Everything it did for me, it would have done for you too. It was homogenizing my photography.

Imagine this. You and I are standing in front of Kilauea. There's a Pacific cyclone a hundred miles offshore, and the biggest thunderhead either of us has ever seen is towering over the ocean behind the volcano, showering lightning bolts like Steven Spielberg on a $200 million budget. The volcano itself is erupting spectacularly, and to top it all off, there's an incredible sunrise behind us spraying orange and pink light all over the clouds and casting a huge rainbow over the volcano and in front of the storm.

The light's changing fast, so I have the F-100 on Program auto-exposure, in matrix metering mode and autofocus. I take a picture. You forgot your camera, so you ask to borrow the F-100 and you take a picture too.

We just took the same picture. Of a once-in-10-lifetimes scene. Not only that, we both took the same picture as all the other tourists standing around looking at the scene through the viewfinders of their auto-everything cameras. We all took the pictures our cameras wanted to take, not the pictures we wanted to take.

If I were using the all-manual Leica IIIf shown at the top of this blog entry instead of the F-100, I would have to make a bunch of creative choices. I would have to choose a shutter speed and an aperture setting, for example. The combination of the two would determine whether the scene in the picture looked "normal", "dark", or "light". But each individual choice has implications beyond darkness and lightness. A slow shutter speed would give me more lightning bolts, but it would blur the lava spewing out of the volcano. A wide aperture would blur the foreground, and would slightly decrease the overall sharpness of the picture. If I want a slow shutter speed and a wide aperture, I get a lot of light. That's OK if I want the picture to look lighter than the scene looked in real life - but if I don't want that, I'll need to put some filters in front of the lens to block some of the light.

When I use the IIIf, I have to think about what I want the picture to look like before I push the button. It has no automation, so it can't whisper the siren song of automation in my ear. It doesn't want me to take average pictures - pictures just like yours and everyone else's - because it doesn't want me to take any particular kind of pictures at all. All the creativity and intelligence stay in my head, where they belong.

If you want to take pictures just like everyone else's, set your camera to automatic.

If not, take responsibility. Set your camera on manual.

If that sounds scary, don't worry; in the next entry in this series I'll tell you what to do next.