As I mentioned on my tutorial "make mine extra crispy", proper exposure is probably the most important factor in the quest to obtain clear, sharp images. Okay, so how do you properly expose an image? The answer is to make sure that you Expose To The Right (ETTR). ETTR means that you are exposing your images higher than what your camera's meter considers "correct" (i.e. you are slightly overexposing your images). This captures the most image data your camera's sensor can record. In practice, that means adjusting your exposure on your subject so that your histogram goes as far to the right of the chart as possible without blowing out (clipping) your subject. Notice that I say "subject", because blowing out the background usually isn't a problem for most portrait situations. Many emerging photographers take pains to avoid blowing out any part of an image, and that's a mistake. Who really cares if that light fixture contains any highlight detail? It's more important that your subject is properly exposed. Here is an example (from a b&w image) of what I mean by making sure your histogram goes all the way to the right. This is proper exposure:
And here's an example of an underexposed image - the chart falls far short of the right edge:
Yes, the image can be "fixed" by moving the exposure slider to the right in Lightroom or adjusting levels in Photoshop, but when you do so the image quality is degraded and the final results much less pleasing than if the image were properly exposed in the camera. The more you need to move the exposure sliders on the computer, the more muddy (noisy) your image will become. Here are a few principles to consider first: (1) DO NOT trust the image in your camera's LCD screen as a judge of proper exposure. Even when shooting raw, the image on your LCD is an in-camera jpeg that has been processed by your camera's computer. If the image is underexposed, the algorithm in the camera's jpeg processing will boost the levels. This may make the image look fine on the LCD screen, while being dramatically underexposed in practice. Only use your camera's histogram to judge exposure. (2) Think about your metering mode. Over the years I've found that I get my most reliable results using the evaluative metering mode (known as matrix metering for you Nikon users). This averages out the exposure for the entire scene. I'm not saying this is the only way to go - there are many photographers who successfully use the center-weighted or spot metering mode. However, I shoot lots of weddings, corporate events, and small children. In all of these situations, I have to move quickly with not a lot of time to set up shots. Evaluative metering gives me the most margin for error. If you are even slightly off with spot metering (or your camera gets fooled) you could end up with an unusable image. (3) Know how to use your exposure compensation (EC) dial. When using automatic metering such as aperture-priority, using EC will override the camera's metering. When using manual metering, EC means setting the exposure so the needle is not in the center of the grid, but either left or right depending on your judgement. Now I'm going to run through my decision making process from some actual shoots (you may recognize some of the images from some recent blot posts). In this image, I'm using aperture-priority mode and Evaluative metering. The camera is a Canon 30D with a 24mm f1.4L lens. ISO 400, f1.8, 1/100 sec, +1.33 EC:
(1) The first thing I do before I shoot is to set my camera's ISO. In this image I used ISO 400. From experience I pretty much know exactly what ISO I need to be at. When shooting indoors, I never go below ISO 400. I usually start at 400 and see what my settings are. Most often I'm shooting at 800 or even 1600. Don't be afraid to boost your ISO. A little noise in an image is okay, but getting a blurry image from motion blur or camera shake is not. With today's cameras, noise at ISO 800 is pretty much a non-issue. (2) The next thing I do is to set my aperture. In this image I used f1.8. At ISO 400, I needed a fast (wide open) aperture to get an acceptable shutter speed. I also like shooting with large apertures due to the limited depth of field it gives me. It's a look that clients can't get themselves with their point and shoot cameras - or even with their consumer SLR cameras with kit lenses. (3) Okay, here's the key part - setting the exposure compensation. In this image, you'll notice light coming in from behind and to the left of my subjects. The walls are also white. So the bulk of this scene is much brighter than the subjects themselves. I know that I'm going to need +EC. I moved my EC dial to the right until I was at +1.33 EC. In other words, I overrode my camera's evaluation of the scene by 1 and 1/3 stops. In practice, this means that the aperture setting I selected, the camera reduced its shutter speed from about 1/250 to 1/100. As it turns out, even this wasn't enough. I ended up having to increase the exposure by yet another 1/2 stop in Lightroom, so I really needed about +2 EC. However, a half-stop move in Lightroom produces quite an acceptable image, while a 2 stop correction would definitely have resulted in a muddy image. I could have taken a few test shots to dial-in the exact exposure, but in this fast-moving situation, it was more important that I capture the moment, so setting the camera at +1.33 EC was just a quick estimate that worked out well in practice. (4) Is any part of this image "blown-out" because I exposed to the right? Yes, the light reflecting off the floor in the bottom left corner of the image is blown out. Do I care about that? Not at all. Here's another example from a wedding I shot last Saturday. Canon 5D w/24mm f1.4L lens, ISO 1250, f1.6, 1/100 sec, +1.67 EC:
(1) ISO was set to 1250. Despite the bright light coming from the window, this hotel room was very dark - particularly in the direction the bride is facing. I needed at least ISO 1000 or more in order to have a fast enough shutter speed to get a sharp image. (2) Using aperture priority mode, aperture was set to f1.6. Again, because of the very dark room I needed a fast aperture to get an acceptable shutter speed. (3) EC was set to +1.67. With the very bright windows behind the bride (and thus greatly affecting the camera's exposure reading) I knew I needed to compensate with adding plenty of positive EC. As in the previous example, I needed to make a half-stop move to the right in Lightroom, so the correct EC would have been +2.33. However, in this fast-moving environment getting it within a half stop was quite acceptable. (4) Notice that the windows are totally blown out. Not only does this not bother me at all, I actually like it. It wraps the light around my subjects and creates an ethereal look. In my camera's LCD screen, I saw that the windows were blinking black, telling me that they were blown out. A subject doesn't have to be back-lit to require +EC. In this image, this adorable little girl is being side-lit by a window camera right. She's standing in front of a bright yellow wall, which brightens the overall scene, in turn underexposing my subect, so the image required +1EC to get proper exposure. Canon 30D w/24mm f1.4L lens, ISO 800, f2.0, 1/200 sec, +1EC:
Here is a situation that most photographers wouldn't think to add +EC. It's an outdoor image on an overcast day. You can't get much more even lighting than a very cloudy day, right? There's light coming from all directions, right? Yet even in this situation, the image required +1EC. That's because much of the image is comprised of the sky, which - although cloudy - is still much brighter than the subjects. Remember, any time there is a very bright element in the frame you're subjects are likely to be underexposed without adding +EC. Canon 30D w/24mm f1.4L lens, ISO 100, f7.1, 1/125 sec, +1 EC:
Summary: When indoors, my default camera setting is +.67 EC. The only time I take my camera into a neutral EC setting is when I'm dealing with a front-lit subject on a bright day, or if I'm shooting with off-camera strobes. Adding +EC moves your exposure to the right (ETTR), which captures the most image data and produces crisp images. You can use +EC regardless of whether you're using aperture priority in combination with the EC dial, or whether you shoot manual and just meter with the needle to the right. Do I ever use negative EC? Almost never. If I were shooting, say, a groom and his groomsmen with dark skin wearing dark suits in a room with dark walls then -EC would be necessary. I've shot 1,500 frames at some weddings without needing to use -EC even once. Practice ETTR and I guarantee you'll get crisper, cleaner images! |
