Friday, March 30, 2012

Photography 101 | ISO


Just joining in? Here's what you've missed:
Photography 101 | Coming Soon!
Photography 101 | Aperture
Photography 101 | Shutter Speed

Welcome back to my Photography 101 series! Are you ready to learn all about ISO (International Standards Organization)?

Depending on how old you are, you may remember the days of pre-digital photography when you had to purchase rolls of film. You may even remember that the film came in different speeds (100, 200, 400, 800, etc). Basically, film speed is a measure of how sensitive the film is to light. The lower the number the less sensitive to light the film; therefore, you have to have a lot more light or the photos will be too dark. The higher the number the more sensitive to light the film; therefore, you don't need as much light to expose your photos.

The ISO setting on your digital camera controls the camera's sensitivity to light, and it works exactly the same way as film speeds do.  The lower the ISO setting, the less sensitive your camera will be and the more light you will need to take photos.  The higher the ISO setting, the more sensitive your camera will be and the less light you will need to take your photos.

To demonstrate this, I took a few photos of Zoe laying on the couch in our living room. For each image, I had my aperture set at f/1.2 and my shutter speed set at 1/640.  I picked these setting simply because they would allow me to demonstrate the change to the exposure as I changed the ISO settings. The ISO settings from top to bottom are 100, 200, 400, 800, 1600, 3200, and 6400, which are options available on my camera.  Yours may be different.


By now, I'm guessing that you've probably realized that the series of photos I took while changing the aperture, while changing the shutter speed, and while changing the ISO, all look about the same. As I went through the range of options available, the resulting images went through a range from light to dark. This means that there are multiple combinations of settings that will allow enough light to enter the camera to properly expose each photograph, and it's going to be your job as the photographer to decide which combination you are going to use. We will be talking about this in depth in future posts, but first we need to learn how to know if our photo is going to be properly exposed or not.

This week, I encourage you to experiment with your camera's ISO settings and become familiar with the effect of changing ISO on your photos.  Now that you know a little bit about aperture and shutter speed, you can experiment with different combinations and see what happens to the photos.

Then join me back next week, to learn about using your camera's exposure meter!

Michele Whitacre is a portrait photographer serving Phoenix, Arizona and the surrounding area. Visit Michele's website at michelewhitacrephotography.com. Become a fan of Michele's work on Facebook. Follow Michele's updates on Twitter.

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