DIGITAL PHOTOGRAPHY AND UNDERSTANDING EXPOSURE

Monday, January 02, 2006

To sum up the essence of this post, my ability to get the exposure correct has improved considerably since going digital due to instant feedback, and I notice I am making fewer errors when I take a picture and re-shoot to correct it.

In the years that I was using film, I worked very hard to get the exposure right. I used to take notes occasionally so that I can get some feedback on the exposure once I get the film developed. And each time when shooting, if I found the need for exposure compensation, I would think hard to get the right value. Despite all that, there were always errors. And with slide film, any small exposure error was a serious problem. I used to get it wrong pretty often despite all the care and effort I took to get it right.

Come digital and we had the instant feedback system. You could check the image in the LCD to verify if everything is ok, and there was the histogram to give you more accurate feedback. But when you are doing action photography or shooting birds, you can't afford to shoot first, look at the histogram and make another attempt to get proper exposure. So I had to learn to get it right the first time. I started observing the subjects, the light pattern and the camera's ability to get the metering right on a particular scenario. Continuous observation of this kind helped me understand the camera’s metering better, and hence make the correct exposure compensation on the first shot.

I still do make lot of mistakes with exposure, but I am getting it right more often. Images discarded due to bad exposure have come down to as much as 75% of what used to be six months ago. I have found that same improvement was difficult in film since I would not get the much useful instant feedback. Here are a couple of things I did which helped me improve.

1. I kept studying the histogram after each shot wherever possible, even if I am fairly sure that the image will be fine. It is also important to study the image on the LCD to get a feel of the exposure.

2. I studied the lighting condition of the subject and each time, and I made an attempt to check how the camera's light meter behaves for such a lighting condition. For example, I now have a better understanding of metering when I shoot a bird with sky in the background. If there is blue sky, I don't need to compensate. If it is bright sky, I need to compensate by +1EV(0.5 to 1.5 depending on how bright it is). In case of overcast sky(when photography is better not done), I need to compensate up to +2.0 EV and I may still not get a good image. There can be other factors - such as how much of the frame is covered by the subject and how much by the sky and take takes time to perfect it. So I still end up changing exposure by -1/3 to +1/3 when processing the RAW image. But it is important to note that I used to discard images six months ago because the exposure error used to be worse.

3. Similar to previous point, I also started studying the compensation needed depending on the color of the object. For example, the camera meter never gets it right if you are shooting a bird that is completely black(or white), or if your subject is bright snow. I haven't worked much with such subjects since going digital, I am yet to make more improvements on it. But I have noticed that I can expose a black colored bird much better than I used to do earlier.

It may be possible to fix exposure problems during post processing, but obviously, best results are obtained when the image is exposed properly. I usually do not expect very good final image if I need to make a compensation of more than 0.5EV in during post processing.