A quick guide to lenses

There are many different types of lenses in all variations of shapes and sizes, these lenses come in all sorts of prices also. In this post I hope to be able make sense of lenses, what they are, what the various numbers on them are and what they are best for (but there really is no set rule that a certainlens can only be used in set circumstances, this is where being creative comes in).

So, where do we start? Well let’s start with focal lengths or the “mm” sizes on the lens. The “mm” refers to the focal length of the lens.  A 50mm lens is said to be the lens that closest matches what the human eye sees. On a compact camera with a zoom on it will say, for example, “3xZoom” this is the focal lengths of that particular lens. A DSLR lens, however, will have this size in “mm” for example a 70-210mm lens would be the equivalent to “3xZoom. 

This is a very basic list of the various lenses and what they tend to be best for:

Wide .... less than 35mm – this makes it a wide-angle lens and is excellent for landscapes and for in confined spaces (estate agents use them to photograph inside rooms to enable them to fit more of the room in).

Standard .... more than 50mm – this is a telephoto lens and brings everything closer to you.( not to be confused with a zoom lens as a standard “prime”* lens is a fixed lens)

*a prime lens has a single focal length. Prime lenses tend to be that of better quality images and construction, this is because there is less glass involved within the lens making for a sharper image. It is worth noting that most lenses are at their sharpest in the middle of their aperture range. There are some exceptions such as zoom lenses with large apertures (f1.4, 1.2, or 1), this is because they are specially designed to be used at these maximum apertures. Primes lens are great for the fact that they will force you to think more about the composition of your shot and after, what better way to zoom in than to use your legs.

Zoom .... more than 200mm – this lens is often used for sports and wildlife photography.

So now you know about that types of lenses there are it would be good to finish this post with what all the letters and numbers mean that encircle the camera lens. Knowing these will help you to ensure that you purchase a lens that best suits the needs you may have. Luckily deciphering these numbers is a lot easier than you would think. 

F/number

The f/ number represents the aperture value. The higher the f/number the smaller the aperture and the “slower” the lens, the larger the f/number the wider the aperture and the  “faster” the lens allowing more light in enabling you to take sharper photos in lower light.

Ratio number

This is the set of numbers that are shown as a ratio, these indicate the widest possible aperture for the lens. (The aperture is the f/# and in where the light goes in). In the case of zoom lenses you may see one or two values, say 1:2.8 or 1:4-5.6. The first example refers to the 2.8 as the widest aperture available (f/2.8) and the second example the value varies between f/4 to f/5.6 depending on the focal length.

So with these things in mind I hope that this has helped to make sense of the lenses that there are out there. The only thing now is for you to decide on what prices you are prepared to pay.

Below are some videos about lenses that may help you decide further about what lens is right for you.

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