Aperture is a term you heard a lot in the photography world as it has quite an impact on the images that you take. It is also a very important aspect in flower photography. It is often the cause of some confusion but in this article we will explain it step by step and show you why it is so important.
Essentially, the aperture is the size of the hole in the lens that lets the light through. It is not related to the camera. You use the cameras controls to adjust it but it is the size of the hole in lens.
A big, wide open aperture will let more light through (f/1.4, f/2.8 etc). You can see this in the diagram below. The black ring depicted in the diagram are the 'blades' in the lens that are adjustable to produce a bigger or a smaller hole. These blades are controlled by the settings on the camera. These blades are 'pulled back' out of the way to make the hole bigger and pushed in to make the hole smaller.
A small aperture, a narrower hole, will let less light through (f/16, f/22 etc).
So far, so good?
However, as well as controlling the amount of light that gets through the lens, the aperture influences another very important aspect of flower photography - the depth of field or DoF.
Depth of field refers to how much of the image is in or out of focus.
A narrow depth of field means only a small part of the image will be in focus and this is often used in flower photography as it gives a very soft and dreamy effect to the rest of the image.
A big (or wide) depth of field means that a lot of your image, if not all of your image, will be in focus. This can also be used to good effect in flower photography – it all depends what you are trying to achieve.
So essentially, a wide open lens (a big aperture) will produce a narrow depth of field and a small aperture will produce a big depth of field.
(You may have noticed from the diagram that a BIG aperture actually corresponds to a SMALL 'f' number!! This is correct and its just there to confuse the beginner!! More on this elsewhere but essentially the aperture is 1 / 'f' number. So numerically 1/1.4 is bigger than 1/22).
To summarise. Generally speaking in flower photography you will want to have a bigger aperture, not specifically to let more light into the camera but in order to achieve a narrower depth of field. This usually holds true when taking pictures of flowers at close range. When taking pictures of a scene, a garden as a whole or a field of flowers you may want to use a smaller aperture to produce a wider depth of field so that more / most of your final image ends up being in focus.
For those of you who are interested there is a much more detailed and scientific explanation of aperture to be found on the Wikipedia web site. Beware, it gets complicated !!!