matt Shell

Understanding your camera (part III)

Hey, I'm back.  That's good news.  I've been doing this for a few weeks and I haven't given up yet.  That's a good sign! 

For the record, it's really hot today.  Not hot for people who live in hot places, but hot for us living in the bay area.  It's gonna get above 90 today. This is a good time to talk about how the heat affects your photography.  Well, that's easy... it doesn't, but it makes it hard to be outside.  There's a tool that will help you, though.  It's called cold beer.  You can buy it almost any place that sells beverages.  Keep it in your fridge and it will taste much better.  It really helps you take better pics in hot weather.  In fact, the more you drink, the more interesting your pictures usually are.

Okay, let's finish our beers and move on to the real focus of this post, the third part of the exposure triangle... ISO.  We've previously talked about shutter speed and aperture, so that leaves only one thing, ISO.  In the old days... years and months and months ago, people used film and when using film, ISO was a measure of how sensitive a film was to light. It was measured with numbers like 100, 200, 400, etc.  The lower the number the lower the sensitivity of the film and the finer the grain in the shots you’re taking.  Now each roll of film had a different ISO number, so the only way to change that was to put in a different roll of film, with a different ISO number. 

Today, with digital cameras, all we have to do is change the knob that controls our ISO. In fact, we can change the ISO for every picture we take if we wanted to!  In digital photography, ISO measures the sensitivity of the image sensor, instead of the sensitivity of the film – the lower the number the less sensitive your camera is to light and the finer the grain. Higher ISO settings are usually used in darker situations to get faster shutter speeds – however the cost is noisier shots. Noise in digital photography refers to that grainy areas that you see, usually in the dark spots of a photo and usually when using a high ISO.  So you can choose the ISO you want to use, but again, like in the other aspects of our exposure triangle, you'll affect the other settings on your camera.   Remember, it's all connected, so when you change your ISO, you’ll notice that it impacts the aperture and shutter speed needed for a well exposed shot.  If you bumped your ISO up from 100 to 400 you’ll notice that you can shoot at higher shutter speeds and/or smaller apertures.

Shutter Speed + ISO + Aperture = Your Exposure

Okay, now let's go get a beer!