Tips on Deciphering lens codes and numbers

Have you ever tried deciphering lens codes? Let’s be honest, it can be sometimes very confusing, all those numbers and letters. At first they don’t make any senses, but learning the art of deciphering lens codes leads you to make a better decision on purchasing a new lens or picking up the right lens for you projects. In this article I am going to cover what those numbers and letters actually mean.

Deciphering Lens Codes and Numbers

In previous articles I discussed the Lens Focal Length that usually follows by millimetre (mm). If there is only one number (e.g. 24mm) it means that it is a Prime Lens and if there are a range of numbers (e.g. 24-70mm), you are looking at a Zoom Lens with variable focal lengths.

Also we looked at the Focal Length and how it affects the Angle of View. Understanding these codes allows you to choose the correct focal lens for your photography projects.

For deciphering Lens codes I divided them into two categories, Universal and manufacturer’s specific codes. In these article I am going to take a look at Universal codes only.

For deciphering Lens codes I divided them into two categories, Universal and manufacturer’s specific codes. In these article I am going to take a look at Universal codes only.

Usually on the barrel of the lens or under the lens cap you see this symbol ( ø ) followed by a number in millimetre. This is the  Filter Size of your lens.

Here is another important number to learn about lenses. On the lenses you see a series of number that often reads as 1:X. (That x can be any numbers). For instance you may find these combination of numbers on your lens 1:2.8, which means that the maximum (widest opening) aperture of the lens is f2.8.

It is very useful specially when you are in the market for buying a lens. This takes us to the most important part of this article.

In some lenses (Usually inexpensive zoom lenses), you see a range of numbers such as (1:3.5-4.5). What does it mean?

The variable maximum aperture means that when the focal length is set to the lowest number, the lowest maximum aperture is the lowest number of this range, and as you zoom (increase the focal length) the aperture changes to higher number. For example a camera kit comes with a short zoom lens, something like 18-55mm, which is the focal lengths of this lens. When we look at maximum aperture of this lens it usually is 1:3.5-5.6. When shooting at 18mm the maximum aperture that the lens provides is 1:3.5. As zooming to higher focal length the maximum aperture changes, even though you didn’t change it! If we shoot at 55mm the maximum aperture would be 1:5.6.