One of the most requested photography concept explanations (and by most requested I mean like 3 people asked about it) deals with the topic of ISO. Which is actually really funny to me because ISO is one of the few more advanced photo settings that we used to deal with back in the age of film cameras.

Don’t tell me you don’t remember going to the store and looking at rows and rows of Kodak or Fujifilm. You might have called your mom on your brand new cell phone and asked “Should I be getting 400 or 800 film?” The numbers 400 and 600 refer to the ISO of the film.

What does the term ISO mean?

When dealing with film, the term ISO refers to the films sensitivity to light. Now that most of us have moved to digital the definition has changed a little bit (now it refers to the sensitivity of the image sensor) but this “sensitivity” functions the same with regards to your photos whether you are shooting film or digital.

Here is all you really need to know to use your ISO settings effectively: Lower numbers (like 100 or 400) mean less light sensitivity, and a finer grain. Higher numbers (like 800 or 1600) mean more light sensitivity, but also more grain.

Feeling confused? I’ll show you two wonderful examples from my friend Ami’s (of the lovely blog Elizabeth Anne Designs) vow renewal over New Years. Micheal Norwood was one of the photographers and he shot exclusively using film for that event (so talented! I’d like to get there one day).

What do HIGH ISO and LOW ISO settings look like?

Here is an example of a photograph taken with a very HIGH ISO setting.

See all of those speckles in the photo? Those are called grain, and they are there because Micheal use a film speed that was very high. (I don’t know what it was, but maybe something like 1600). He might use this very grainy, very fast film for two reasons. He might just want a particular style of picture, very grainy black and white images. Or he might know that he was going to be in situations where there wouldn’t be a lot of light available, so he needed a very fast film to soak up as much of the light as possible.

Here is another HIGH ISO photo example. Can you see why he chose to use a faster film speed? It was very dark in the room, with only wall sconces, candles lighting the aisle, and some light at the front. He needed to capture as much light as possible using a faster film speed in order to get beautiful images like this one.

Here is another example by Michael Norwood, taken the same day, using a LOW ISO. See the absence of grain? It’s beautiful! I love how smooth and pretty images with LOW ISO are. (I also love really grainy black and white images like the ones above as well. I’m pretty easy to please.)

Michael Norwood’s beautiful photos probably got the point across, but I took some of my own of my trusty dwarf to help you see how different ISO settings affect the same photograph.

Note: In yesterdays white balance post, I took one picture and changed the settings over and over. For this post, I took multiple photos with different ISO settings. The ISO setting was the only thing I changed each time.

For this first photo, I turned the camera on automatic and the camera decided that a setting of ISO 100. Do you remember what that lower number means? (Hint: Less grain, but also less light “soaked up” into the film sensor.)

ISO 200

ISO 400

See how much brighter the image taken with ISO 400 is than the image taken with ISO 100?

ISO 800

Wow! In this situation, ISO 800 is very bright (in photography this is called overexposed). By turning up the film speed I was able to get a lot more light in my photos.

For these photos, I moved my little dwarf friend into the bathroom to show you some photos taken in a situation with less light. For these photos I again didn’t change any settings other than the ISO so you could see how increasing the ISO gives you images with more light, but also with more grain.

ISO 800

ISO 1000

ISO 1600

ISO 2000

ISO 2500

ISO 3200

I thought it was still kind of hard to see the noise in the above photo, so I took it into an editing program, adjusted some settings to make it lighter, and cropped it in. This really helps us see how much noise is in the image when the setting is at ISO 3200.

Fancy dSLRs like mine have ISO settings that go really high (all the way up to 3200 for the Canon 50D). Most point and shoots or prosumer level dSLRs won’t go all the way up to ISO 3200. One of the things expensive dSLR cameras are supposed to do is eliminate the film grain (sometimes called noise) as much as possible, so the HIGH ISO setting photos on my camera don’t have as much noise as the photos taken with your camera might. The more expensive your camera is (generally) the less grain you will have in your photos.

What I’m trying to get across here is that my camera at ISO 1600 will likely have less noise than a point and shoot set to ISO 1600.

It seems like a lower ISO (less light being “soaked up” into your photos which might mean they are darker, but also less noise) is always going ot be the best choice for me. What are some examples of situations where I would need to consider using a higher ISO (more light being “soaked up” into your photos, which means lighter images, but also more noise)?

From Digital Photography School blog:

Situations where you might need to push ISO to higher settings include:

• Indoor Sports Events – where your subject is moving fast yet you may have limited light available.
• Concerts – also low in light and often ‘no-flash’ zones
• Art Galleries, Churches etc- many galleries have rules against using a flash and of course being indoors are not well lit.
• Birthday Parties – blowing out the candles in a dark room can give you a nice moody shot which would be ruined by a bright flash. Increasing the ISO can help capture the scene.

It’s important to remember that there are several different settings on your camera that will contribute to photography success. You know how to change the white balance, and now the ISO. Figure out if your camera has a setting that lets you change only the white balance and ISO (“P” or Program might let you do this), and start taking pictures on different ISO settings to get a feel for how the two work together.Once you understand how those two work together, you’ll  be all ready to introduce the concept tomorrow’s post, shutter speed, into your bag of tricks!

Also:

• Jenna Cole Aspirations Workshop
• Paige’s Maternity Shoot
• October Photo Challenge: Week 3