What is ISO?

I’m not going to go into a lengthy description of how your digital camera or SLR is affected by ISO, but I am going to tell you what it means, the basic rules, and why it matters, because knowing the basics of ISO and film speed will make your photography better!

And I’ll use this photograph to demonstrate. (It was left out from making egg sandwiches earlier and I thought, this will do nicely!)

But first, what does ISO stand for? It means International Standards Organization and it refers to the industry norm for sensitivity of emulsion based film, with 100 ISO (aka Slow Film) being not so sensitive to 1600 ISO (aka Fast Film) which is extremely sensitive to light. TRANSLATION: Different lighting conditions may require you to adjust your ISO sensitivity to get the best photo possible.

Here’s how you can relate:

You may remember purchasing film at the store before you got that digital camera of yours, and you may recall that you most likely picked film that said “400” or “800” on the side of it, or some number close to that. Well, that’s because these are two “safe” film speeds for beginners that work okay in low light and in bright light. On occasion, you probably got your film back and noticed that some photos looked great, and others looked way too dark or light. That’s because you couldn’t adjust your film speed (ISO) to adjust for the different lighting conditions, but with digital you can!

Here are the basic rules:

– Use an ISO of 100 or 200 when taking photographs outside in sunny conditions
– If the sky is overcast or it is evening time, then use an ISO within the range of 400 to 800
– Night time or in cases of low light you might need to set your digital camera ISO to 1600; if you don’t then your photo will appear too dark if at all

How it will improve your photography:

If you set your digital camera to a low ISO, for example 100, the resulting photograph will be better quality than one set at 1600. The higher the ISO, the more grainy the photo will look. Therefore, go for a low ISO number whenever possible.

Here’s a few examples to show you the difference.

ISO: 100
Looks very smooth and of high quality.

ISO: 200
Still looks pretty smooth.

ISO: 400
You can see the image starting to appear slightly grainy in the shadows.

ISO: 800
The photo looks very grainy in the shadows and gradients.

ISO: 1600
Here the quality of the photo looks very poor, and no settings have been changed in regards to the resolution. Only the ISO has changed. And this lesson becomes especially important for those focusing on macro photography, where ISO is of most importance.