ISO–The Big Three of Photography Part 3

This is part of a series of posts about How to Shoot in Manual Mode. Follow the links to read the other posts about WHY I USE MANUAL MODE, APERTURE, SHUTTER SPEED, HOW I PUT THEM ALL TOGETHER, and WHERE TO BEGIN CHOOSING YOUR SETTINGS! You can also download a helpful Manual Mode Cheat Sheet here.

ISO–What the heck is ISO? I first became aware of ISO in the days when I used a film camera. At first, I wasn’t really sure what it all meant other than the ISO 100 or 200 film had pictures of sun and ISO 800 film showed clouds. So, consequently, if I was going to be photographing outdoors with lots of sun, I chose ISO 100 or 200 film and if I was going to be photographing on a cloudy day, I chose ISO 800 film.

But here’s the real story. ISO measures the sensitivity of the camera sensor (or film) to light. Lower numbers are less sensitive to light but produce little noise/grain while higher numbers are more sensitive to light and tend to produce more noise/grain.

Here is an example:

I took 2 photos of an apple. The left one was taken at ISO 200 and the one on the right at ISO 3200. I wanted an extreme example so that you could easily see the difference. Look at the background in these photos. The background of the ISO 200 shot is creamy and smooth but the background of ISO 3200 looks grainy or noisy. ISO’s in between 200 and 3200 will have gradually increasing amounts of grain.

So, obviously, as a general rule you want to keep your ISO as low as possible. Does this mean that I will always photograph at an ISO of 200? Absolutely not!! When photographing indoors, I really dislike (and this is putting it kindly) using the on-camera pop-up flash (a.k.a. The Flash of Death) and would much rather have a somewhat grainy photo than the harsh light the pop-up flash produces. In any lighting situation, the ISO I choose depends on the lighting conditions. If I am outdoors during daylight hours, I generally use ISO 200 or 400. If I am photographing indoors, my ISO might increase to 1000 or more.

This example was taken outside on a fairly bright day. There was enough light to keep the ISO at 200 while still maintaining a high enough shutter speed to get a crisp photo while hand holding the camera.

ISO 200 Aperture: f/5.3 Shutter Speed: 1/200

However, in this example, it was later in the evening in the mountains and the sun was setting and somewhat blocked by the trees. I had to increase my ISO to 800 to keep a high enough shutter speed for a crisp photo–she was moving, after all.

ISO 800 Aperture: f/4.2 Shutter Speed: 1/160

In this next example, I was taking pictures of my son and I reading books during the day in a room with a large window. I was able to keep my ISO at 400.

ISO 400 Aperture: f/2.0 Shutter Speed: 1/60 (just barely fast enough to hand hold the camera and not get a blurry picture)

However, in this example, I was taking photos in a room in my house that has very little window light on a cloudy day. I had to increase the ISO to 1000 to get a good exposure and still hand hold the camera. If you look close there is some grain in the photos but, thankfully, I didn’t let that deter me from taking these pictures since they are some of my recent favorites.

ISO 1000 Aperture: f/2.0 Shutter Speed: 1/60

Some other situations where you may need to increase your ISO in order to be able to get a good exposure–indoor sporting events (you’ll need a high shutter speed to capture the motion without blur and the indoor lighting will probably not be enough), inside a church (generally not well-lit and many will not allow flash especially during a wedding ceremony), and birthday parties (blowing candles out in a dark room can give some fun light, but you’ll have to increase your ISO to capture it.)

Some technical caveats: 1) Not all camera sensors are created equally. DSLR sensors are larger and better at keeping noise levels low at higher ISOs than point and shoot cameras. Professional-level DSLRs are even better! 2) The ability of DSLRs to use higher ISOs with less grain is something that camera manufacturers have really improved in the last year or two. If your camera is more than 2 years old, it will probably not handle high ISOs as well as a newer camera. I can speak from experience–my Nikon D300 handles higher ISOs MUCH better than my older Nikon D70. On my old camera, I rarely used any ISO higher than ISO 800 if I wanted a decent photo. This feature is one of the main reasons I upgraded my camera.

So, figure out how to change the ISO on your camera and play around with this feature. Try to get some good shots indoors without using your “Flash of Death.” Figure out how your camera handles high ISOs by comparing photos at all the different ISO settings. And, as always, please feel free to ask questions in the comments section!