Understanding the aperture of your lens

Ever wondered why you just don’t take great photos…

You need to learn about the aperture of your lens, and how to control it. When automatic cameras were introduced, it suddenly unleashed a wave of photographers who could, most of the time, take a photo that was correctly exposed and look half decent. But not outstanding. That is where aperture comes into it. The difference between a very good photo and a happy snap is all about what is in focus and what is not.

We can control this in any image by changing the aperture of the lens for each image. For any decent photographer, mastery of this concept and the application of it means a lot as you can ‘pick out’ subjects or objects in a photo and have them in focus, out of focus and so on. This allows you to ‘layer’ your images and this can make all the difference to your photography.

What is Aperture?

Lenses let light into your camera, and if they let in less light they will have most things in focus, and if they let in more light they have only a single point in focus. Aperture is measured in ‘f stops‘. A ‘fast lens’ would be f1.2 and a ‘slow’ lens would be f5. The faster the lens, the more things will be ‘out of focus’ when a lens is wide open either side of the object in focus. Learning how to control this to get things to look the way you want is a very important photographic skill. The best way to show you this is to show you some images of the same object.

A Panasonic f1.7 20mm lens and a few objects on a table

The images below were taken with a fixed lens. We call this a ‘prime lens’ as the lens does not change it’s focal length. It just stays at 20mm. We can focus the lens at 20mm but we cannot zoom in to make things closer. But we can change the aperture. This can range from f1.7 to f16.
f1.7 is wide open
f16 is almost a pinhole
Look closely at the images below and you will see the difference that a change in aperture in a lens makes.

f1.7 – lens aperture is wide open

The flower is in focus, but the bowl 60 cm behind the flower is out of focus and the cabinet behind it is a blur. The base of the vase that the flower is in is also slightly out of focus. We say that this image has a ‘shallow depth of field’ as the focal point is very narrow. The flower is in focus and a few centimetres either side of it are also in focus.

f8 – lens aperture is halfway open

The flower is in focus, the vase base is almost in focus and the bowl of citrus is almost in focus.

f16 – lens aperture is almost a pinhole

Everything in the image is in focus. You can even see the individual glasses in the cabinet and pick out details all over the image.

How do you change the aperture on your camera?

Read the manual for starters. Once you work out how to adjust the manual settings, take some sample images of the same object then look at them closely with your computer. They will not look very different on your camera as you cannot see the details of the image on the screen. You should have the option of setting the camera to ‘A’ (aperture priority) or ‘S’ (shutter priority). Try these settings and see what the effects are, especially the Aperture Priority setting. Aperture and Shutter speed must be in balance for the photo to have correct exposure (not be too bright or too dark).

Just remember that a good shot takes a bit of planning:

  • set the camera ISO to 100 or 160
  • set the white balance to adjust for indoors, cloudy, sunshine or flouro lights
  • get as much light on the subject as you can from behind where you are standing
  • take a few shots of each setup, as you always get a few dodgy ones in the mix

As usual, if you have any questions just let us know.