There’s a genuine thrill to using a macro lens for the first time, and once you’ve given it a go, you’ll find the enjoyment doesn’t fade. Thanks to the way a macro lens lets you magnify tiny objects, these specialist optics are all about discovery, and they’re indispensable for many subjects, such as still-life, floral and wildlife photography.
What’s more, with most of them offering short telephoto focal lengths and wide apertures, they can be used for portraits, too.
Macro lenses come in all shapes and sizes, so which is the right one for you and what you're shooting?
Central to a macro lens’s function is the ability to focus more closely to the camera than a regular lens, and while this can also be achieved with accessories like close-up lens filters, extension tubes or by reverse-mounting lenses onto the camera body, those all come with their drawbacks, for instance loss of image quality, loss of focusing range, loss of autofocus, or just plain fiddliness. Therefore dedicated macro lenses are the best option.
But with so many on the market, and a lot of different prices and specifications, how do you know which is the right one for your photography? Here we lay out the main things to look for. . .
Magnification & reproduction ratio
This is probably the first place to look, because while many lenses have the word ‘macro’ in their name, sometimes that’s scientifically true, and sometimes it’s for marketing purposes. A true macro lens will reproduce the subject at a ratio of 1:1 and in terms of magnification this is 1x. What it means is that the subject is being focused on the sensor at life size. So, if you were to shoot a 1p piece at 1:1 or 1x, it would fill as much of the frame as though you were placing it on the sensor.
A macro lens's reproduction ratio should be shown along with focusing distance on the barrel. Here, the lens is focused at infinity, so the reproduction ratio is 1:10. At the closest focusing distance it will be 1:1, or lifesize.
Many lenses that call themselves macros have a 1:2 (half life size) or a 1:4 (a quarter life size) ratio or higher; that’s fine for close ups, but it’s not true macro, so look in the specs, or on the barrel to make sure you’re getting the magnification you need.
It’s important to remember though that the lens’s greatest magnification can only be achieved at its closest focusing point; if you focus further off, you don’t get such great enlargement.
Some macro lenses, like the Laowa 25mm F2. 8 2. 5-5x Ultra Macro can reproduce the subject at even greater than life-size.
Even more magnification?
It’s perfectly possible to go beyond 1:1 or 1x if you desire, and this can be done by adding close up filters or extension tubes to a macro lens, or by picking a specialist model, such as the Canon MP-E 65mm 1-5x Macro f/2. 8 or Laowa 25mm F2. 8 2. 5-5x Ultra Macro. Therein, you’ll get reproduction ratios like 2:1 (twice life size) or 5:1 (five times life size).
Crop factor
Does sensor size affect magnification? No. All a smaller sensor does is crop the amount of the focused light that’s recorded. Therefore if you shot the same subject with the same lens on a full frame and then an APS-C sensor with the same resolutions, the subject would look larger in the resulting image, but technically the magnification is the same.
What this means in practise is that you can get an enlarged view of the subject shooting with a macro lens on a body with a cropped sensor, but that’s true of lens.
Focal length & working distance
Macro lenses vary a lot in focal length, and there’s a good reason for that. It’s all about ‘working distance’. Working distance is the measurement between the front element and the subject (not to be confused with minimum focus distance, which is measure from the sensor to the subject), ie the space from your lens to what you’re shooting. The two are twinned, of course. So, while you might be fine with a working distance of just a few centimetres when shooting florals, still-lifes or flat subjects like maps, if your subject is a skittish animal, a bit more working distance means you’re less likely to alarm it.
The longer the focal length, the greater the working distance will be; longer lenses focus further off to achieve a 1:1 reproduction. So while with a Nikon AF-S 60mm f/2. 8G ED macro lens has a minimum focusing distance of 0. 185m, a Nikon AF-S VR 105mm f/2. 8G IF-ED macro lens has a minimum focus of 0. 314m.
Focal length affects a macro composition like any other. On the left the pic was shot with a Laowa 15mm f/4 1:1 macro lens, on the right a Canon EF 100mm f/2. 8L Macro IS USM lens. Credit © Laowa / © Matty Graham
Focal length & composition
Just as with any lens, focal length also affects composition and perspective. Macro lenses with short focal lengths, like the Laowa 15mm f/4 1:1 macro lens, enlarge the subject in relation to the background, so you’ll see more of the environment. Macro lenses with longer focal lengths compress perspective, so the background should be less distracting.
More about working distance
Working distance also comes into play when you need to add light to the subject. The greater the working distance, the more space you’ll have to add lights, or to avoid blocking the natural light with your shadow. If the working distance is short and you want to add light, you’ll probably need a ring flash or macro light like the Canon Macro Ring Lite MR-14EX II, which sits on the end of the lens.
The smaller the working distance the harder it is to shoot the subject without blocking the light on it; that's where accessories like Canon's MT-24EX Macro Twin Lite come into their own.
On the other hand, the lower the working distance a lens has, the easier it is to alter the position of the subject to improve your composition, because you’ll be able to reach around the camera to do it, rather than upsetting your shooting position. So, shorter working distances can be an advantage for still-life and floral shots.
Other factors
Some macro lenses also use image stabilisation, which can help you to produce sharper images at slower shutter speeds. How much use this is to considered macro work is debatable, as you’ll likely be shooting from a tripod and using a self-timer or remote release to avoid camera shake. But if you’re planning to shoot macro handheld, such as when capturing wildlife on the fly, or use the lens for more general photography or portraiture, it’s worth bearing in mind.
Macro lenses with image stabilisation – in this case Nikon's Vibration Reduction on a 105mm macro lens – help improve sharpness when shooting handheld.
On the same score, some lenses have focus limiters, so you can bias the AF to work within a certain range and speed up focusing. Again, this is more likely to be useful for handheld shooting as, if you’re working from a tripod, you’re more likely to be manually focusing when shooting macro.
. digitalrev.com2018-5-10 03:00
