In the last blog we discussed becoming familiar with your camera, going out and spending some time shooting photos in Auto mode. Hopefully that little exercise was fun and you learned what your camera is and isn’t capable of doing on it’s own. It’s time to progress. Knowing and understanding the fundamentals of photography will mean the difference between good photos and great photos. It’ll allow you to artistically express yourself through your camera, achieving the results you envisioned. You’ll understand that a “better camera” doesn’t necessarily take better photos but it does make achieving those results easier. There are other features in high-end cameras that make them better but they are totally unrelated to this discussion.
The word “photography” was created from the Greek roots phōtos, genitive of phōs, “light” and graphé, “representation by means of lines”or”drawing”, together meaning “drawing with light”. It’s all about light. How efficient you capture and render that light is going to determine the quality of your image. It’s time to discuss ISO, Aperture and Shutter Speed. Not only should you know what each one of these things are, it’s important to know how they relate to and influence each other.
ISO, also known as film speed, or in the case of digital, sensitivity. Back in the days of film photography, you chose your film speed based on the light conditions that existed. These days, it’s your camera’s sensor that captures the light and processes the image. Generally speaking, ISO ranges from ISO 100 or 200 up to ISO 6400 (and much greater, depending on your camera). Your base ISO, usually ISO 100 on Canon, ISO 200 on Nikon will produce the highest quality image. Beginning with your base ISO, say it’s 200, each increment increases by the power of 2. So, your adjustment sequence is ISO 200, 400, 800, 1600, 3200, 6400 and so on. Each step between the adjustments essentially doubles the sensors light sensitivity. 400 is 2x more sensitive than 200, and 800 is 2x more sensitive than 400. This makes 800 4x more sensitive than 200. “Great. Simple enough…”, you’re probably thinking. “…but how does it relate to my everyday photography?” Great question, allow me to elaborate.
Each adjustment to ISO doubles the sensitivity. When you double the ISO sensitivity, you also reduce the exposure time in half. Assume the exposure time for ISO 200 was 1 second:
ISO 200 – 1 second
ISO 400 – 1/2 of a second
ISO 800 – 1/4 of a second
ISO 1600 – 1/8 of a second
ISO 3200 – 1/16 of a second
ISO 6400 – 1/32 of a second
This is important to know especially when you’re dealing with low light conditions and your subject is moving. You can bump up the ISO, allowing you to increase the shutter speed and freeze the action.
Now for the bad news. Each time you increase the ISO, you introduce something called “noise”. Referring back to film days again, it was grain that increased with higher ISO’s. As I stated earlier, you ideally want to shoot as close to the base ISO as possible. Your base ISO will give you the highest and cleanest image. The more you increase the ISO, the more noise you’ll see in the image. Here’s an example of noise in higher ISO’s:
You’ll notice quite a bit of difference between the two photos. Most of the higher end camera bodies will let you shoot effectively up to ISO 6400 but for the majority of you the above photo is what you can probably expect to encounter when shooting higher ISO’s. Sometimes a little noise won’t even effect the image and most photo programs will clean up a fair amount of noise. Get the shot. Worry about the rest later.
Tomorrow we’ll discuss Shutter Speed and Aperture.