Canon lenses: what you need to know
The most important piece of kit in your camera bag isn’t your Canon DSLR; it’s the glass you put in front of it. This might be a cliche, but it’s true. A high-calibre lens attached to a beginner-level camera will always produce better quality images than a top-end pro body fitted with a cheap kit lens.
That said, there’s an incredible amount of creative potential in the versatile 18-55mm kit lens that came with your EOS camera, and the chances are you may not be fully exploiting it. This guide will give you all the confidence you need to start doing just that.
We’ll explain how you can get the best from the lens you own, whether that’s a standard zoom, a wide-angle, telephoto zoom or specialised macro lens for close-ups (see also our guide DO or Di: your lens markings explained).
We’ll show you how different focal lengths can transform your photographic results, and explain how best to deal with optical problems you might face in the field. Get ready to see things more clearly…
Canon Lenses: kit lenses and standard zooms
‘Invisible’ standard zooms
The standard kit lens that came with your EOS offers a focal range of 18-55mm that’s perfect for everyday photography. On APS-C D-SLRs, it offers the equivalent field of view as a 29-88mm lens on a full-frame camera such as the 5D Mark II, enabling you to take in everything from landscapes to portraits to close-ups.
Pictures produced by the humble standard zoom have a very natural look when the lens is set at 35mm (55mm equivalent), because this is said to match the focal length of the human eye. Used in this way, these lenses become ‘invisible’, enabling viewers to concentrate on the subject of the picture without getting distracted by the kind of optical effects associated with very wide or long lenses.
Although standard zooms are capable of capturing pictures that are very easy on the eye, they can still produce less-than-flattering portraits if they’re not used with care.
Unless you’re a fan of caricatures, don’t stand close to your subject and simply zoom out to the wide 15mm or 18mm setting of your kit lens to take the shot. In particular, avoid putting people’s faces near the edge of the frame as this is where the distortion tends to be strongest.
It’s much more preferable to take some steps back and zoom in to the longer end of the zoom at 55mm. This will compress their features
and produce a much more flattering picture.
All lenses suffer from optical defects such as distortion and vignetting (where a frame’s corners look darker than its centre) but imaging software is now so advanced it can help fix such problems. Canon’s DPP and Adobe Photoshop can perform fixes at the Raw processing stage, so picture file quality is preserved. Keep in mind when composing that correcting for distortion can lose some detail at the picture’s edges.
Kit lenses aren’t the fastest focusing lenses among Canon’s EF and EF-S arsenal, and you might find they struggle to lock onto a subject in low light. Rather than relying on the camera to choose the autofocus point, switch to single AF point selection and manually select one yourself.
The centre focus point is the most sensitive, so a good tactic to use for subjects that aren’t likely to move is to first focus on the subject using the centre AF point and One Shot AF, then lock the focus (using either the AF lock button, or by switching the lens to manual focus) and recompose the shot for the best composition.
Fast prime lenses
One of the best kit lens upgrades you can buy is a ‘fast’ 50mm lens. Why should you spend money on a lens that duplicates a focal length you’ve already got built into your standard zoom? Because the wide maximum aperture of a fast 50mm lens means that a very fast shutter speed can potentially be used (hence the ‘fast’ reference), which is incredibly useful for low light and indoor photography.
The wide apertures on offer in the 50mm f/1.8 (affordable), 50mm f/1.4 (reasonable) and 50mm f/1.2 (ludicrously expensive!) also give a shallow depth of field, meaning beautifully smooth, blurred backgrounds are possible.
Canon lenses: wide-angle zoom lenses
Getting the measure of wide-angle lenses
Lenses in the region of 10-18mm are capable of capturing pictures of vast scale and depth. The trade-off to swallowing up so much of a scene in a single frame is that it’s more difficult to arrange ‘clean’ shots.
It’s easy for compositional clutter such as branches and lamp-posts to sneak into the edge of a picture, so get into the habit of running your eye around the viewfinder before you take the shot (zoom out slightly to help you spot the intruders).
Wide-angle lenses also frequently suffer from flare, so always fit a lens hood or shield the front element from direct sunlight using your hand or your body.
Finding foreground interest
Wide-angle pictures can lack impact if they’re simply used to try and squeeze as much of a distant scene as possible into a single frame. Everything just ends up too small. The trick is to find interesting foreground detail and get in close to it in order to lead you into the scene and give the shot depth.
Wide-angle lenses also capture more depth of field than telephotos, especially used on EOS models with smaller APS-C sensors. This brings benefits for landscape photography, where front-to-back sharpness is what you’re aiming for most of the time (see our 10 Commandments of Landscape Photography – and how to break them).
Full-frame vs APS-C
The APS-C image sensors most EOS models use are smaller than ‘full-frame’ (same size as a 35mm film frame) ones in the likes of the EOS 5D Mark II, so capture a lesser area of the image. This gives a magnifying effect, or ‘crop factor’, of x1.6 – apply this to the lens to get the ‘effective’ focal length.
This is great for long lenses, where a 500mm one effectively becomes 800mm. It’s not so good for wide-angle lenses, where a 20mm lens narrows to a ‘true’ 32mm.
These extreme wide-angles produce a unique view of the world, in which every straight line becomes curved. The typical 8-15mm focal lengths can resolve a 180° view, which makes them great for shooting interiors, expansive scenery and in-your-face distorted portraits – and you really do need to be up close and personal with the subject to make the most of this effect.
Anything more than a few feet from the front element will look tiny in the final picture. It’s also easy to catch your own feet and shadow in the shot if you’re not careful!
If you do a lot of architecture photography, you’re probably aware of the curious effect of converging verticals – in which pointing a wide-angle lens up at a building makes it appear as if it’s about to fall over.
Wide-angle shot with converging verticals
There are three solutions here. First (and worst) is to reduce the effect using Photoshop’s Lens Correction Filter. This does mean that you’ll lose parts of the picture as the software stretches the picture to correct the anomaly. Second, if possible, you can simply stand further back and employ a longer focal length in order to flatten out the perspective.
Third, choose a tilt-shift lens, which enables you to fix the problem in-camera. These are fiendishly expensive lenses (Canon’s TS-E 17mm f4L lens is approx £1950) so consider hiring one for a weekend instead of buying.
Canon lenses: telephoto lenses
Wide apertures, shallow depth
As well as offering you more reach, telephoto lenses provide you with more blur or, more precisely, with a shallower depth
of field. A telephoto lens used at f/4 will give a narrower band of apparent sharpness in an image than a wide-angle lens used at the same aperture. You can exploit this fact by sandwiching a sharp subject between a blurred foreground and background for punchy results.
It’s a very simple, but effective, technique that wildlife photographers frequently use. The trick is to make sure that you’re close enough to foreground detail for it to appear blurred, and that the backdrop is far enough from the subject for it to be rendered soft, too (find out how to Master Live View on your Canon DSLR).
Telephotos are big and bulky lenses, so they’re not the easiest to use hand-held. There’s a reason many come with a tripod collar, after all. The minimum shutter speed rule of thumb for handholding applies to teles just as it does for shorter lenses – that is, make sure the shutter speed is at least equivalent to the lens’s focal length (so 1/200sec for a 200mm lens) – but faster is best!
Image stabilisation (IS) has been a game changer for hand-held shooting though, with the latest high-end EF telephoto lenses boasting up to four stops of support (so the same 200mm lens in our example could now be used at a shutter speed of around 1/13 sec and still produce sharp shots in the right hands).
Another creative tool for the long lens photographer is the effect of perspective. Telephoto lenses make it easier to compress a picture’s elements so they appear closer together than they are in reality.
55mm at f/22
It’s a great technique for landscape and architecture shots. Perspective depends on your position in relation to the subject rather than the lens used; images shot from the same spot with 50mm and 500mm lenses show the same perspective.
70mm at f/5.6
But the 500mm focal length concentrates the effect as it’s focusing on a smaller area.
For many people, a superzoom might be the only lens they ever need, offering a vast range of focal lengths in a handy take-anywhere compact package. However, there are obvious compromises to be made when you’re squeezing 18mm through to 200mm into an affordable lens.
Superzooms have relatively slow maximum apertures (such as f/6.3 at 250mm) so they’re not as naturally suited to low-light shooting as faster (brighter) lenses. Focusing and image quality is also less likely to hold up to critical scrutiny.
But there’s a lot to be said for convenience, and while other photographers miss shots as they spend time changing lenses, the superzoom user can continue to get their pictures.
Filling the frame with a telephoto zoom lens
Warning: long lenses can be addictive! For frame-filling impact, you can’t beat the reach of a tele. A subject doesn’t double in size when you double the focal length: it appears four times as big.
That said, you need to be fairly close for frame-filling shots of small birds and animals. Because images are magnified so much, the effects of camera shake are too. Rock-solid technique (and a rock-solid tripod and head) are advisable.
Canon lenses: macro lenses
Look for texture
One of the most enjoyable aspects of macro photography is that it enables you to reveal a world that’s normally hidden from the eye. And you don’t have to travel far to find suitable subjects.
Texture, whether it’s peeling paint on a door,
a rusting lock or lichen growing on a wall makes for striking abstract studies. Just remember to keep the back of the camera parallel with the subject in order to maximise the depth of field through the shot.
Choosing the right macro lens
Macro lenses enable you to get frame-filling shots of small subjects, but not all macro lenses are made equal. Some lenses are badged as ‘macro’ to signify that they focus close up. But a true macro lens is one that gives you 1:1 magnification of a subject – that is, it’ll be captured at life size by the sensor. There are various focal lengths on offer, too.
55mm on kit lens
The longer the lens, the further you can be from the subject in order to get that life-size magnification.
100mm macro lens
This is useful when you’re photographing insects which might scarper if approached too closely, and gives you room to light the subject well.
Even though you’ll need to use small apertures to buy you as much depth of field as possible when working close up, you should avoid using the smallest on offer on your lens (which is usually somewhere around the f/32 mark).
Light waves passing through such a small hole tend to bounce around and not all get focused in the same place on the sensor, leading to soft pictures. Equally, think twice about using the widest aperture (such as f/2.8) unless you want just a wafer-thin degree of sharpness in your picture.
Macro lenses are more than just for close-ups
Even though macro lenses are optimised for close-focus photography, they can still be used just like any other lens for ‘normal’ shooting situations.
For instance, a 60mm macro would make a razor-sharp substitute for a standard 50mm lens, with the bonus of getting in ultra-close when you need it to. The fast maximum apertures on offer in macro lenses mean a 100mm f/2.8 becomes an excellent choice for low light photography, if a bit slow focusing.
Focusing for macro
Don’t rely on autofocus when using a macro lens (find out How to set your autofocus for macro photography). Depth of field is very narrow when working at such extreme magnifications, and if the AF system gets it wrong by even a millimetre, well, it might as well be a country mile off, and the results will be unusable.
It’s far better to take charge and use manual focus, something which Live View and its focus magnification aid make light work of (find out What is Live View: free photography cheat sheet) . In fact, this feature, twinned with the Vari-angle LCD screens on the 600D and 60D, makes for an unbeatable macro outfit for low-level work.
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on Saturday, April 28th, 2012 at 7:00 am under Photography Tutorials, Tutorials.
Tags: Canon, Canon lenses, hot, lens