Photography Tutorial: ISO to Capture Natural Light and Drama
In my last digital photography blog, I discussed exploring your DSLR’s manual settings to create photos with some depth and punch. Manually choosing your aperture settings is one way. Today, we’ll talk about the importance of adjusting your ISO.
In photography, ISO refers to film speed, or how sensitive film is to light. Digital cameras don’t use film, but they do have a sensor which behaves similarly, so the term stuck with the advent of digital cameras. The obvious benefit to digital photography is that you don’t’ have to change your film if you want to use a different speed.
ISO values typically range from 100, 200, 400, 800, 1600 and 3200. The higher the number, the more sensitive the camera is to light. In bright daylight or under studio lighting, 100-400 would be suitable. In low light situations or when shooting action, 800 would be a better place to start.
As I stated before, I am not a huge fan of flash photography (though using a flash to fill in shadows on a face on a bright sunny day is a great idea). Allowing your camera to automatically burst a flash might overexpose your photo or wash out the beauty or drama of the natural light available. Flash can brighten up what’s immediately in front of you but loose compositional detail.
For example, in the following photo, I used my camera’s automatic setting to take a picture of the interior of a tavern. Notice how the foreground is lit, but the background is very dark. The image is boring and
In the next image, from the same spot, I switched from the automatic setting to Av (aperture priority), turned off the flash and set the ISO at 800. Notice the incredible difference in lighting and detail. Now you can see further into the building and all of its the fun, quirky décor.
Although the foreground light is slightly blown out and the entire image is a bit overexposed, you get the idea. Dumping the flash for a higher ISO presented an opportunity to take advantage of the natural light and ambiance of this particular place.
When choosing ISO, you always want to go with the lowest value possible, as faster speeds can produce some graininess the higher you go. But keep in mind that if your ISO is too low, your camera will adjust its shutter speed to properly expose the image. Had I used an ISO of 100 or 200, my camera might have chosen an exposure time of 1/15 of a second, for example, and that’s way too long to hold your camera still for a photo. If it was a still shot, meaning that there wasn’t any human movement in the photo, then using a tripod and a long exposure is fine, and even really dynamic. But, if people were in the shot, the result would be blurry. So, the key is to find a speed fast enough to focus in on the scene, while avoiding as little noise (grain) as possible.
Here’s another example:
This is a concert photo shot in a dark theater with a flash.
It’s okay. It documents the event and is good enough to post on your Facebook page. “Look where I was last night!”
But, it’s not nearly as dramatic and amazing as something like
This was shot with an ISO of 800 and an aperture of 5.6. Remember that a lower aperture setting allows in more light as well.
When it comes to shooting pictures in low light situations, don’t be afraid to shut off the flash. Experimenting with ISO and aperture values can produce surprising results!