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Dawn Michelle Photography |
Exposed! November 2008 |
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Hi! Ah, isn't this weather fantastic? I love it! I really love Thanksgiving, too. Reminds me to reflect on all the little (and big) things I'm thankful for.
I hope everyone has a wonderful Thanksgiving!
Dawn Attebery
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Exposed!
I have an embarrassing confession to make. Years ago, when I first started getting interested in photography, I got some books and read through the composition chapters, finding that fairly easy to grasp (but not necessarily easy to do). But when it came to the chapters on exposure, I skipped them. I figured I didn't have to learn it because my camera was going to figure all that out for me. Plus, I guess I was intimidated by the subject.
For those of you who don't know what I'm talking about, by exposure, I don't mean how much publicity a person is getting. In photography-speak, it is all about the light, baby. Basically, it's how much time the light hits your film or sensor, whichever the case may be. And it is extremely important to understand if you want to become a better photographer.
There are three camera settings that affect exposure:
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ISO - this used to be the number on the film box. You know, 100 for daylight, 400 for action, etc. In the digital world, on your SLR, at least, you can set the ISO you want to use per shot. The higher the number, the less light you need to get a proper exposure.
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F-stop, aka aperture - This is how large the lens opening is. The higher the number, the smaller the lens opening. The higher the number, the greater the depth of field (stay tuned for a later issue on depth of field). In short, depth of field refers to how much of the image is in focus. A shallow depth of field means a small number for the f-stop or aperture (say, 1.8) and results in a small portion of the image being in sharp focus.
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Shutter speed - Picture a curtain in your camera that lets light in when you press the shutter release and then closes after a certain amount of time. The shutter speed is actually 1/x seconds, where x is the number you see on your camera. (Yes, I have a math degree and like to introduce algebra whenever possible.) In other words, if you see 125 on the camera, your shutter speed is 1/125 of a second. The smaller the number, the longer the "curtain" is open. So a shutter speed of 60 is 1/60 of a second, which is a longer period of time than, say, 1/250 of a second. (And, yes, we will talk about shutter speed in a future issue, too, so stay tuned).
I agree that this is a lot to digest. And to further complicate things, if you are using a digital camera, you have to get your exposure pretty darn close to perfect when you take the picture or you will lose detail when you try to correct the exposure in post-processing (photoshop or whatever) or when your lab's software tries to correct it.
In point-and-shoot cameras, these items are usually set for you by the camera. But they may not be correct because the way they figure it is based on the light in the scene you are photographing. There may be some really bright spots and some really dark spots so your image may be either overexposed or underexposed. Even in your SLR, the camera may not determine the proper exposure.
Overexposed means there was too much light hitting the film (or sensor). Underexposed means there wasn't enough light hitting the film (or sensor). Here are pictures to illustrate the differences:
Overexposed Underexposed Proper exposure
Proper exposure includes details in the shadows (darkest spots) and the highlights (brightest spots). Notice in the properly exposed image that the right side of the face has the proper exposure even though the left side is in shadow. The shadows and skin tones are too dark in the underexposed image. The highlights (bright spots) are so blown out on the overexposed image that there is no longer detail.
On your SLR, you have some options:
- aperture priority mode - you set the aperture (f-stop) and the camera figures out the proper shutter speed
- shutter speed priority mode - you set the shutter speed and the camera figures out the aperture (f-stop)
- manual mode - you set both the shutter speed and aperture (f-stop)
I prefer using manual mode because I am a control freak. Seriously, I like to tell the camera exactly what I want because different shots call for different settings and I want to be sure to get it right. For sports photography, I'd want to use a fast shutter speed to stop the action unless I'm going for a blurred motion look which can be pretty cool. Often when shooting portraits, I use a low aperture for a single person to get the background to go out of focus and thus be less distracting.
This is a big topic so I will end with a few cautions:
- If you have a shutter speed of less than about 90 (1/90 of a second), use a tripod to avoid camera shake. Camera shake is that little movement of the camera when you press the shutter release. You don't know you do it but your camera knows it and if you have camera shake, your image will not be in sharp focus. Along with a tripod, set a timer or use a remote shutter if you have the shutter open for a long time.
- If you have a lot of people in one photograph, use a higher number for your f-stop (aperture) so that everyone is in focus. If you can keep the depth of the people shallow, you can be sure to get everyone in focus. In other words, if you line 20 people up, each person behind the one in front of them, you'll need a bigger number for the f-stop (aperture) than if you had 4 rows of 5.
- A lot of cameras do not yield great results at a higher ISO. I try to keep it at 100 or 200 if I can. If you go to a very high ISO (say, 1600), your print may have a lot of what we call digital noise, which looks like film grain. You lose detail, basically, and get a grainy look.
I hope I shed some light (ha!) on the subject of exposure. I also hope that explaining it the way I see it in my own little mind was helpful. Please feel free to ask questions if you have them. It is a very important concept to understand if you want to get serious about photography.
Dawn | |
