Basics: know when to stop...

It goes without saying that one of the most important elements in photography is light. This blog gives some more details about exposure, aperture and other useful terms related to light. 

The amount of light captured whilst taking a photo, is known as the exposure. Exposure is controlled by:
1. Aperture
2. Shutterspeed
3. ISO

The aperture is a hole within a lens through which light travels into the camera body. With a big hole (small number, for example F/2.8), a lot of light will come onto your picture. And thus with a small hole (big number, for example F/16), less light will travel into your camera body. 

Basically, large aperture (f/2.0, f/2.8 etc.) lets in more light to the camera shutter for an exposure, whilst small aperture (f/11, f/16, f/22 etc.) has a smaller opening in the lens. 

After aperture, let's talk about shutterspeed. So a camera shutter is curtain in front of the camera sensor. This curtain stays closed until the camera fires. The faster your shutterspeed is, the faster the curtain will be closed and your picture will be darker than with a slower shutterspeed. 

And then ofcourse: ISO. ISO indicates the level of sensitivity of your camera to available light. The lower the ISO number, the less sensitive your camera is to light. A higher ISO number increases the sensitivity of your camera to light. Turning your ISO up to 400 gives you a lighter image than a picture with ISO 200. 

Be in control

These are the basics for good exposure. And good exposure is so very important for great images. Ofcourse you can use the automatic setting but then you have no influence on the actual result. Or you can choose to shoot semi-automatic. This is where for example you set your shutterspeed and the camera then decides on the aperture. You still don't have full control over the entire process. 

I always prefer to shoot manual. Good start is to shoot in Aperture Priority Mode (AV for Canon) and check the result. So set an Aperture (for example F4) and make a picture. Now check the shutterspeed and ISO that was used by the camera. Switch your camera to Manual and now you can be in control. Do you want more or less light? You want to change your depth of field? When making this creative changes, you need to know your stops: 

This table shows you all the details you need to know. It might look a bit tricky but actually it's not. Each step in Aperture, Shutterspeed or ISO is called a stop.

When you go from F2.8 till F4 it's 1 stop. If you are on F11 and want three stops back (more light) you have to change your aperture to F4. It works the same with Shutterspeed and ISO.

So let's take for example this well-exposed image that was shot with the following settings:   F5,6, 1/250 and ISO 200. What to do if you want less depth of field, you don't want the background to be that sharp. 
In this case you should change your aperture to F2.8 or F4. So you go from F5.6 to F2.8. If you take a new image now, it will be 2 stops brighter. You can (should?) compensate this with your shutterspeed and go 2 stops darker there. In this example your shutterspeed then changes from 1/250 to 1/1000. 

And finally, a 4th element can be when you work with flashes. So after aperture, shutterspeed and ISO the power of the flash can be adjusted too. When shooting full power and you switch to half power, the amount of light changes with 1 stop. Depending on your creative goal this gives you a darker image or you can composate it with aperture, shutterspeed and/or ISO as described in this blog. 

Keep the basics in mind and go out there and shoot. Shoot, have fun and get to know your stops.