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Lenses Explained

A lens is one of the most important parts of a camera, without it you'd just have a body which can’t do much of anything. For new photographers, lenses can be a daunting area to explore and a very expensive thing to get wrong so I would like to explain a few things that will hopefully help you on your journey. Choosing the right lens for the task at hand is incredibly important and different ones have different specialities, not to say you can't break those moulds but if you have a creative vision in mind you need to make sure you have the lens to create it. Below I will explain some of the important things to consider when choosing a lens and how different sorts can be used.


There are two numbers attached to each lens, aperture and focal length. The aperture number shows the maximum aperture that the lens is capable of using. Remember the lower the aperture number the wider the opening is, therefore, more light is hitting the sensor, also the wider the aperture the shallower the depth of field. For example, a lens may say f1.8, f4 or f3.5-7. An f number of 1.8 is quite a wide aperture and will let in a lot of light while producing a shallow depth of field. F4 is a bit narrower and so with a lens like this low light shooting may be an issue, The depth of field will also be much greater so the background won't be that blurred. When a lens has a range of f numbers eg f3.5-7 this means that the maximum aperture changes as you zoom. So with the lens zoomed all the way out you can have a maximum aperture of 3.5, this lets in a fair bit of light and will give a bit of background blur if the subject is very close to the lens. Fully zoomed in the lens will only allow you a maximum aperture of 7, this will let in much less light and require a slower shutter or higher ISO to compensate. The maximum aperture of a lens often has a strong impact on both the price and weight of the lens and this is something to consider when you are putting together your kit.

Focal Length

The next number that’s attached to a lens is focal length, this is essentially how zoomed in a lens is. The human eye is roughly comparable to a 50mm lens so a lens with a higher focal length will make your image more zoomed in than what you see with the naked eye, a lower focal length will make the image more zoomed out. For portrait photography 50-85mm is normally the standard as this is what the human eye is seeing and therefore produces images that look ‘normal’, shooting wider or more zoomed will distort the face and create some strange but cool effects.

Some lenses are called prime lenses and others are zoom lenses, all this means is if the focal length can be changed, i.e. can you zoom in and out with the lens. For example, a 50mm lens is just that, 50mm and nothing else. There is no zoom functionality, all you have is that one perspective. A 24-105mm lens lets you zoom from 24mm (which is fairly wide) to 105mm (which is fairly zoomed in). You might be wondering why people would pick a prime lens over a zoom when you would be limiting yourself so much? Well, the answer is they are mostly better, for the same price point you will get sharper and cleaner images with a prime lens than a zoom. On top of that for the same price point, you can normally get a much wider aperture at the same focal length on a prime lens than you can on a zoom. If you think of the ability to zoom as an added feature, then with a prime lens and a zoom lens at the same price, corners must have been cut to add in the zoom feature without raising the price. As a result, a prime lens is normally less versatile but will produce better images/ be much cheaper for the same quality.

The next thing to think about with focal length is distortion. As I said before the human eye sees around 50mm so anything wider or more zoomed will create distortion, this might be a distortion you want though and is part of the creative process. Having a wider angle lens will let you shoot more of the scene but objects in the foreground will appear larger than in real life and the background will be smaller. This can be used to your advantage to make a foreground element more dramatic in the scene or to distort leading lines to really grab the viewer's attention. Longer focal lengths will create something called image compression, this is where the background looks much closer to the foreground and much larger. The will also give a shallower depth of field so the background will be more blurred. Choosing the right focal length is a very important part of the creative process and will make a huge difference to the shot. Using a wide angle for a landscape shot will let you capture more of the scene and get more of it in focus, using a longer focal length will let you get a large dramatic background but with a shallower depth of field. For portrait work a wide angle will distort the features and can make images look either creative or just weird, longer focal length will produce soft bokeh and a larger background behind the subject.

If you buy your camera with a lens it will often be a zoom lens, this is very useful to get started as it lets you see how the different focal lengths behave and gives you more leeway with your shots as you are able to adapt a bit more to the conditions. Once you learn how it all works you can start to invest in new lenses that suit your style and can create the sort of work you want to create.


My final point is price, for many, this is the deciding factor on whether we buy a lens or not. The price of a lens is affected by many things: wider apertures are more expensive, longer focal lengths are more expensive, higher quality is more expensive and general market conditions can change the price considerably. Taking this into account, here are a few things to remember and think about when shopping for lenses. A zoom lens with a fixed aperture (eg 24-105 f4) will be significantly more expensive than one with a variable aperture (eg 24-105 f4.1-7). A lens with a wider aperture at the same focal length will be more expensive, sometimes massively so, eg 50mm f1.8 ~£100, 50mm f1.4 ~£400. Longer focal lengths are often more expensive, especially when you start to get to the specialist end of the spectrum such as the Canon RF 1200mm f8 which costs over £22,000. Something to consider, and I would recommend this to most people, is looking at off brand lenses. Canon lenses are incredibly expensive but there are several third party alternatives such as Sigma and Samyang that are just as good for a fraction of the price. Make sure you shop around and read reviews so you don’t drop a large amount of money on a lens that doesn't meet your needs.

When looking for lenses it's important to keep these three points in mind to make sure you have the right tools for the job. Size and weight are also a concern for some people but since I don't have many lenses this isn't an issue for me. Shop around and find the best deals, pick a lens that has the focal length and maximum aperture that you need and decide if you want a prime or zoom lens. Once you have answered these questions for yourself and started looking you will find loads of lenses you want to buy, it will just be a question of affording them.

If you found this information helpful or if you have any questions I would love to hear from you, leave a comment down below and I will get back to you.


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