About Photography: Exposure, The Triangle and going Manual

Exposure

What is exposure?

Exposure is how an image is captured and how much light is captured. Let's imagine a window. The size of the window determines how big the aperture is: a low aperture value equals a big windows that lets through lots of light. Curtains or window shutters are like the shutters inside cameras: the longer the window is open the more light gets inside. ISO is similar to tinted glass or even sunglasses: a low ISO value let's through little light like wearing sunglasses. And that's basically what exposure is or how a camera works.

Exposure is measured in exposure values EV.

Exposure Triangle

In our previous posts we have talked about shutter speed, aperture and ISO. They make up the "exposure triangle". Knowing how to use each one of those will ensure you'll always make a well exposed image. But it's no exact rocket science. There's a lot of experimentation involved. It comes down to how we want the finished photograph to look like.

From high to low:

aperture: a sharp image with deep focus - a soft image with shallow focus

shutter speed: an image with no movement - lot's of potential motion blur

ISO: lots of big grain, artifacts and a softer image - very fine grain and a clear image

Going from Full Auto to Manual

While full auto makes photography easy as "point and shoot" these days, it doesn't let you create the type of pictures you'd necessarily want. Going to straight to manual surely teaches a lot, but there' no need to make such a big jump. Most cameras are equipped with many different regimes that let you manually change one setting, but let the computer take care of the others:

TAv: shutter and aperture priority mode - this lets you manually change the aperture and shutter speed but automatically changes the ISO settings while shooting

Av: aperture priority - this lets you change the aperture, but automatically changes the ISO and shutter speed

Tv: shutter priority - this lets you change the shutter speed, but automatically changes the ISO and aperture settings

Sv: ISO sensitivity priority - this lets you change the ISO, but automatically changes the aperture and shutter speed

In every mode where the camera takes over you can still change the values by setting a range of values the camera can choose from. For example if I'd like to shoot a soccer match I'd use Tv, because it lets me keep shooting at high shutter speed which is crucial for a sports game. The camera can change the ISO and aperture settings. Obviously really high ISO and aperture settings are a no-go for the lack in image quality. That's where I can set a range: for ISO from 100 to 1600 and for aperture from 2.8 to 11. This ensures me that all images will be of good quality.

You could also set it to full Auto and put a range on the shutter speed. Using ranges on all settings is a smart way of using that mode.*

Where you have to go manual

Long exposure images. It's something cameras can't do on their own. Shooting in the darkness of night or using a 10stop filter will effectively blind the camera. But doing long exposures is no rocket science. Simply take a well exposed image before shooting. Set the filter on the lens and calculate how long the shutter speed should be knowing you'll need to increase the exposure value by 10 stops. In the night is trickier. You'll have to use a flashlight or a distant light as a focusing point and take a sample shot with a high ISO. That way you'll quickly get an idea what the real image might look like once you set the ISO lower and shutter speed longer.