Whatever lens you have on your camera, it will have a number of numbers, letters and abbreviations on it, either on the barrel or the end of the lens casing, but do you know what they mean? Although some will be manufacturer specific, the most common are shown below, along with quick explanations of what they mean:
'55mm' or '14-24mm'
This number which is followed by 'mm' is the lens focal length, and tells you how wide a scene you can capture. The field of view you can see with your eyes (without moving them!) is around a 50mm focal length, and so anything which gives a wider field of view is called 'wide angle' (less than 50mm) and anything which has a more zoomed field of view (more than 50mm) is called 'telephoto'. If there is just one number e.g. '50mm' then this is a prime lens with a single focal length. If there are two numbers e.g. '14-24mm' then it is a zoomable lens with a variable field of view.
f2.8 or f5.6-6,3
These numbers, which may be shown with or without the 'f' show the maximum aperture of the lens. Smaller numbers are generally on more expensive lenses, as the greater the maximum aperture the more light the lens can let in. More expensive zoomable lenses will also have just one number, meaning that the maximum aperture doesn't change as you zoom in and out. Conversely, cheaper zoomable lenses usually have two numbers (e.g. f5.6-6.3) meaning that the maximum aperture (and the amount of light it can let in) gets smaller as you zoom.
Numbers next to a Ø symbol (on the end of the lens)
This is the diameter of the lens, and this is important to know if you intend using filters, as this is the diameter of the filters that will fit your lens.
A number with 'ft' or 'm' next to it
This is the minimum focus distance of your lens, i.e. the minimum distance to an object that you will be able to achieve focus. Macro lenses tend to have much closer minimum focus distances.
1:1 or 2:1:
This notation is most often used on m
acro lenses and is the magnification factor of the lens. E.g. 1:1 means that the object will appear lifesize on the image. A 2:1 magnification means that the object will appear twice as large as life size on the sensor.
Other markings
There are often a number of manufacturer specific markings on lenses. For example, with Sony lenses, 'FE' means that the lens is designed to fit Sony Full frame E-mount cameras. Similarly 'OSS' means that the lens has inbuilt image stabilisation to inhibit camera shake.
