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Understanding The Types of Camera Lenses


Jo Plumridge

This article is an extract from Issue 66 of Photography Masterclass Magazine
Camera with a zoom lens attached
Zoom Lens
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The single biggest expense for most professional photographers is their lenses. And so it should be. Good glass will improve the quality of your images no end. But there are a huge range and different types of lenses available and it’s sometimes difficult to know where to start. This article will give you a clear idea of what the world of photography lenses entails.

Types of Lenses: Prime vs. Zoom

There are two types of lenses available – prime (or fixed) lenses and zoom lenses. A prime lens only covers one focal length (e.g. a 50mm lens), whereas a zoom lens covers a range of focal lengths (e.g. a 24-70mm lens).

Optically, a prime lens will nearly always be superior to a zoom. This is because it only has one focal length to deal with. Obviously, this means that the glass doesn’t have as many variables to cope with.

In addition, a prime lens will always have one fixed maximum aperture, whilst a zoom will often have a variable aperture range. To get one fixed aperture throughout the zoom range nearly always cost a fair amount more! However, on the flip side, a prime lens is usually more expensive than a zoom lens.

There are exceptions to the rule of course. For instance, the two lenses named in the above paragraph buck some trends. The two biggest camera manufacturers – Canon and Nikon both make several 50mm lenses (Nikon make a f/1.8 and f/1.4 and Canon makes both these plus a f/1.2). You can pick up an f/1.8 version for around $120-$150 (£60-70), which is peanuts when it comes to lenses! And yet, optically (as long as you stop down to f/2) the 50mm f/1.8 is an extremely good lens. However, the 24-70mm f/2.8 Canon lens is, unlike many zoom lenses, not particularly cheap – retailing at anywhere from $1300-$2000 (£900-£1300). But for this price, you get a fixed aperture throughout the zoom range and optically, these types of lenses can compete with most prime lenses.

50mm Prime Lens

Fixed Aperture

A fixed aperture throughout a lens’ focal range means that the lens has one maximum aperture (e.g. f/2, f/1.4 etc). This means that you will always be able to achieve this aperture whatever focal length your lens is on. This can be particularly useful with zoom lenses, as it can be very irritating to want to shoot a portrait with a very small depth of field, for example, only to find that your lens won’t allow this.

This is because cheaper zoom lenses nearly always have a variable aperture. The range is usually f/3.5-5.6 for the vast majority of them. So, with these lenses, you could find yourself being able to achieve f/3.5 at 18mm, but only f/5.6 at 30mm (each lens is slightly different). This can be frustrating and limiting at times, which is why pros nearly always go for fixed aperture lenses. The quality of fixed aperture lenses is also much better and you’ll notice this reflected in the price.

For example, a Canon EF 24-70mm f/2.8 lens (fixed aperture range) will produce much better quality images compared to the Canon EF-S 18-55mm f/3.5-5.6 lens (variable aperture range). The improvement in quality is noted in the price difference between these two lenses.

Zoom lenses can be very useful, particularly if you shoot weddings, events or sports, as they allow you to photograph people unobtrusively. However, I’m a great fan of the theory that you come ready equipped with a zoom in the form of your legs! Wherever possible, I try to use a prime lens. If I could only ever use one lens again, it would be my trusty 50mm f/1.4.

Lens Terminology

Different focal lengths of lenses are grouped together to describe their functions. In general, types of lenses will be a form of either wide-angle, standard or telephoto. Here are the accepted focal length brackets for each type of lens:

Super wide-angle    < 21mm
Wide-angle                21mm-35mm
Standard                    35mm-70mm
Telephoto                   70mm-135mm
Super telephoto       135mm-300mm +

Do bear in mind that these are just general guidelines. The brackets do overlap a little at each end – particularly depending on what manufacturer’s lens you are using. Also, whilst each group of types of lenses are typically used for specific purposes, again there can be overlap. But as a general rule of thumb, super wide-angle lenses are used for architecture, wide-angles for landscapes, standards for street and documentary, telephotos for portraiture and super telephotos for sports, birds and wildlife.

Another thing to take care with is using a suitably fast minimum shutter speed when using heavier and longer telephoto lenses. As a general guide, it’s advisable to use a shutter speed equal to or faster than the focal length of your lens. So for instance, if I’m using a 200mm lens, I’d probably aim for a shutter speed of 1/250th and above. Of course, if you’re lucky enough to have very steady hands you may be able to get away with a slower shutter speed. It’s, however, better to experiment with this when you’re not taking a crucial shot!

Types of Lenses: Specialist Lenses

Image taken with a fisheye lens showing wide angle and distortion typical of this type of lens
Image taken with Fisheye Lens

There are a variety of specialist lenses on the market and there are a few common types of lenses that you are likely to come across. Macro lenses are able to focus closer to an object than normal lenses, offering a 1:1 ratio. They are used for still-life photography of small objects. Fisheye lenses are on the edge of wide-angle lenses and give a distorted view of the subject matter. The centre of the image is magnified, and objects diminish in size in all directions around it. And finally, there are Tilt and Shift lenses. These are used in architecture photography and have small bellows built into them so that you can correct for perspective.

APS-C Cameras and Focal Lengths

If you have what’s known as an APS-C or crop frame camera, then the sensor in said camera is slightly smaller than that of a full-frame camera. The different sensor size isn’t a massive issue for day-to-day use, but it does have a slight effect on your lens and its perceived focal length. To simplify things, using a crop frame camera means that you’ll end up with a different field of view. And the way to work out what equivalent focal length you’ll be seeing, in general, you need to multiply your lens’ focal length by 1.6 for Canon, and 1.5 for Nikon. So, for instance, a 50mm Canon lens gives the equivalent field of view of an 80mm lens.

This doesn’t mean that your lens actually changes focal length by the way! This is just the field of view you are left with. Whilst this can be quite useful with telephoto lenses (as you essentially gain without having to spend any more money!), it’s a bit more a problem at the wide-angle end of things. For instance, on my full-frame cameras, I use a 17-40mm lens. But if I were to use that on a crop frame camera, I’d be left with a field of view of 27.2mm. This is no longer a wide-angle lens of any note.

Fortunately, the manufacturers have realised the problem and make specific wide-angle lenses for the crop frame cameras. For instance, Canon makes a 10-22mm lens specifically for crop frame cameras, which equates to a 16mm field of view. So there’s no need to miss out!

Types of Lenses: In Conclusion

Lenses are a key investment for your photography. Before you buy a lens, do your research. Check out websites and magazines for reviews – new lenses are produced frequently and you want to get the best you possibly can for the money you have. And always spend as much of your budget as you can on lenses. They are what ‘makes’ the photo after all. A great way to make your money go further is to look at second-hand lenses. You can often pick up a second-hand lens in almost perfect condition for a fraction of the price new.

And finally, please don’t forget to fit UV filters (and super slim UV filters on wide-angle lenses) on all your lenses. If the worst happens and you drop your lens, you’ll mourn the loss of a $10-60 (£7-40) filter far less than the loss of an expensive lens!

Video Tutorial: Part One – Introduction to Camera Lenses

By: Mike Browne

There are loads of camera lenses out there, zooms, superzooms, prime, macro, wide… but what are they all for, what do they do and when should you use them? Mike Browne introduces us to the various types of camera lens and shows you what they do.

Video Tutorial: Part Two – Introduction to Camera Lenses

By: Mike Browne

There’s more to understanding your camera lenses than just knowing that a long lens zooms far off things in closer, or a macro is for ‘close up’ photography. In this video, Mike Browne will introduce you to the concept of perspective – that’s how different focal length lenses will alter how your photo looks. In other words, your lenses are where the creative magic starts to happen.

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