Photography Tutorial: Aperture.

This is part two of a series of short non technical photography tutorials for beginner photographers.

The Aperture setting on your DSLR or Mirrorless camera is used to adjust how wide the iris on your lens opens, I know I said these tutorials will be non technical however in this example I must use some technical terms to help explain the reason for the numbers appearing wrong way round. You can see in the image below that the f stop (The number prefixed by f/) indicates how wide that opening is, you may also notice that the smaller the number the wider the iris/aperture, although this seems counter intuitive or the wrong way around it is because the f/ is focal length and the number after it is a fraction of that focal length. To try and keep this as untech as possible let me use a 50mm lens as an example.


If you set the aperture on a 50mm lens to f/2 that means the aperture would be 25mms in width, 50mm divided by 2 = 25mm or 1/2 of 50mm and if you set the aperture to f/11 on the same lens then the aperture would be 4.54 mm or 1/11th of 50mm. Hopefully you can now see why the numbers seem the wrong way round and not worry too much about it and just remember that the smaller the number the wider the aperture.

Effects of Aperture.

Aperture affects the outcome of your images in three basic ways:

1.) Light.

This is pretty self explanatory, the wider the aperture the more light that your cameras sensor receives, this is particularly useful when shooting in low light conditions where you can open your aperture up, let more light in and therefore maintain a reasonable shutter speed (See Shutter Speed Tutorial here ) to help prevent camera shake or motion blur and still get a properly exposed image.

On the flip side you could use your aperture to decrease the amount of light on a very bright day or in a very brightly lit situation so that your image does not end up overexposed or to create a more dramatic looking image.

2.) Focus Amount.

By Focus Amount I mean the amount of the image that is in focus or in photographic terms, the depth of field. In the image below of Max, the Depth Of Field is indicated by the red lines and starts just in front of Max and ends just behind his head and is referred to as a shallow depth of field, you will notice that anything beyond those lines is out of focus and is due to the wide aperture setting of f/2.8 . In the image below titled One Tree Hill, the Depth Of Field is much wider and there is no real need to use red lines to indicate where it starts and ends as almost all of the image is in focus and this is due to the use of a small aperture of only f/11

3.) Bokeh.

Bokeh is the quality of the blur produced in the out of focus parts of an image and is produced by the aperture setting and the characteristics of the build of a lens, it can also be affected by the distance the subject is from the background and a few other things that are more advanced and not something to go into now. So to put it in simple terms in the image below of the Caper White Butterfly the blurry green and yellow background is the Bokeh and in this particular case it is referred to as creamy Bokeh and is very pleasing to the eye. This image was created again with a 50mm lens with a macro filter attached and an aperture of f/5.6, the background was quite a distance away from the subject which all came together to create the beautiful creamy Bokeh.

Caper White Butterfly
Caper White Butterfly

Part Three in the series will be Using ISO Setting. If you would like to learn more about Aperture Priority then visit my other site here

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