Digital Camera Lens Buying Guide - 2021

20/01/2020 2:26 pm

With its seemingly limitless range of options, the world of interchangeable lenses is exciting for any photographer to enter. Understandably, a digital camera lens is one of the most important purchases you’ll make on your photography journey.


To make your next lens purchase as stress-free and successful as possible, we’ve put together the ultimate guide to buying a camera lens. From key terms to lens types, read on for all the information you need to buy the right lens for you.

First things first - will this lens fit my camera?

Picture this: You’ve got a new camera that you love, and are starting to develop specialty skills in a specific type of photography, whether this is macro, landscape, aerial, or astronomy. You’re interested in broadening your tool kit with a new lens, but don’t know where to start. 


To begin, it’s essential to understand which lenses are compatible with your camera. This varies between brands.


Brands such as Canon and Nikon have a few different lens mounts, including those for their mirrorless and DSLR camera offerings. Within these mounts, there are certain lenses that are only compatible with certain models (Full-Frame or Crop Sensor).


Digital Lens Buying Guide

Other brands, such as Panasonic and Olympus, currently operate using a Four Thirds or Micro Four Thirds (MFT) system for which all MFT lenses will be suitable.


Manufacturers provide this essential compatibility information using a selection of letters or acronyms, the meanings of which are provided below.

Lens Mounts

The Lens Mount is the most basic piece of information that you need to know when buying a new camera lens. The brand and mount of a DSLR or mirrorless camera determine which lenses will be compatible with it.


With the exception of Panasonic and Olympus and their Four Thirds and MFT mounts, lenses from one mount cannot physically be mounted directly onto a camera with a different mount.

Basic Lens Buying Guide

Full frame or crop sensor?

Manufacturers use the following acronyms to describe if a lens is designed for use on full frame or crop sensor models. 

Canon and Nikon full frame lenses can be mounted on crop sensor cameras of the same brand, but crop sensor lenses cannot be mounted on full frame cameras. Similarly, Sony full frame lenses can be mounted on crop sensor mirrorless cameras, though Sony crop sensor lenses cannot be used on full frame mirrorless cameras.

Digital SLR:

Basic Lens Buying Guide

Third Party Brands: 

Basic Lens Buying Guide


Basic Lens Buying Guide
Basic Lens Buying Guide

What do all those other numbers and letters mean?

Once you have a basic understanding of which lenses will mount and function on your camera, the next question is: How do you decipher all of the other jargon and choose which lens is the perfect fit for your style of shooting?

Basic Lens Buying Guide

Focal Length

The Focal Length is the first number provided in the name of a lens. It is used to describe the field of view that the lens will provide when mounted on your camera.


Forzoom lenses, the Focal Length will include two numbers as the lens can zoom between two focal lengths using all fields of view in between (e.g. 18-55mm or 70-300mm). Prime lenses offer no zoom and therefore have Focal Lengths of just one number (e.g. 35mm or 50mm).

Lenses with a smaller Focal Length offer a wider field of view, while a larger Focal Length results in a more magnified image. Although the Focal Length of a lens in part determines the type of photography it suits best, this is also dependent on the camera it is mounted to. For example, a larger lens Focal Length will result in a smaller field of view when mounted on a crop sensor camerathan when mounted on a full frame camera.

Basic Lens Buying Guide


The aperture is usually the second number in the name of a lens, and is also referred to as an F-stop. In short, the F-stop tells you the maximum lens aperture, with this key specification reflecting how much light the lens is capable of gathering. Lenses with a larger maximum aperture let in more light, which is desired for shooting in low-light conditions. A larger aperture also allows for shallower depths of field, enabling dramatic images with a sharply focused foreground and blurred background.


Basic Lens Buying Guide

Now for the tricky part. A smaller number indicates a larger aperture and faster shutter speed. For example, an f1.4 lens is considered very fast and lets in plenty of light, whereas an f2.8 lens is a slower lens that lets in less light.


To further complicate things, zoom lenses sometimes feature a varying maximum aperture (ie. Nikon AF-S 18-55mm f3.5-5.6).

When considering lens apertures, remember that the maximum aperture of a lens can be displayed in various ways that all mean the same thing. For example, the following notations all indicate an F-stop of 1.4: f/1.4, F1.4, or 1:1.4.

Image Stabilisation

In the digital age, image stabilisation has become a highly sought-after feature in camera equipment. Some cameras come out of the box with in-built optical image stabilisation, while others require you to purchase a stabilised lens. While this is fairly straightforward, it’s important to know that different brands refer toimage stabilisation technology using different terms, as set out below.

Basic Lens Buying Guide


With the exception of select offerings from a few high-end brands, most modern lenses offer autofocus abilities of some type. Also known as ‘AF lenses’, autofocus lenses enable you to simply point and shoot your camera and get a perfectly focused shot with minimal adjustment. As with image stabilisation, different brands refer to AF features using different acronyms, which are given below.

Notably, some entry-level Nikon DSLRs do not feature built-in AF motors, and instead rely on the motors contained in AF lenses. For these models, we recommend using a Nikon AF-P or AF-S lens.

Basic Lens Buying Guide

Focus on finding the right lens for your camera

The right camera lens can completely transform your photography practice and open up a new range of possibilities for your camera.


Don't forget to check out this blog, for further reading on choosing the right lens to take your photography to the next level. Our brand-specific lens guides are also available to help you finalise your next lens purchase.

Ready to put your new knowledge to use? Explore our range of digital camera lenses now, or head to your nearest Ted’s Cameras store to get advice from a friendly member of our team.


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