Big test

Extreme close-ups are the order of the day, as Matthew Richards delves into the tiny world of ‘full macro’ photography

Get up close and personal with eight dedicated macro lenses

The ‘macro’ badge often seems to be bandied about willy-nilly. You’ll see it applied to zoom lenses that give as little as a 0.33x maximum magnification ratio, or thereabouts, and to prime lenses that only give 0.5x magnification. By comparison, all of the lenses we’ve selected for this issue’s Big Test really go the distance, at least when it comes to short focusing distances, enabling full 1.0x magnification at their closest focus setting. But what does that actually mean?

A macro lens with a 1.0x or 1:1 magnification ratio can reproduce objects at full life size on the camera’s image sensor. For example, if you’re shooting with a DX-format body like the D5500 or D7200, a postage stamp will fill the whole of the image

frame. When viewing photos on screen or in print, this therefore gives the possibility of massive enlargements of the tiny things in life. Shoot a spider or garden bug, for example, and it can take on the appearance of a giant alien invader, complete with astonishing fine detail that’s invisible to the naked eye.

While all of the lenses on test give the same maximum magnification, there’s a wide variation of focal lengths on offer, ranging from 40mm to 105mm. The main difference in practical terms is that lenses with shorter focal lengths have closer minimum focus distances, at which full 1.0x magnification becomes available. A focal length of between 90mm to 105mm is often preferred, as it gives a convenient working distance to the subject, of around 15cm. The minimum focus distance remains the same whether you use a lens on an FX (full-frame) or DX (APS-C format) camera. However, the 1.5x crop factor of a DX camera gives the appearance of even greater magnification.

The DX-format Nikon 40mm and 85mm DX lenses on test are naturally designed specifically for use on DX-format cameras, and produce an image circle that’s only large enough to cover the comparatively small image sensor. They can also be used on FX bodies in ‘crop mode’, although the megapixel count of the resulting images will be very much reduced.

Getting back to shooting distances, the shorter focal lengths of the Nikon 60mm and 40mm lenses shrink the closest available focus distance to 19cm and 16cm, respectively. Bearing in mind that the distance is measured from the ‘focal plane’ near the rear of the camera body, rather than from the front of the lens, you can find that the forward end of the lens comes frustratingly close to the subject in macro shooting. Not only do you risk scaring away small bugs that you’re trying to photograph, you can also find that you’re blocking light from reaching the subject. The problem can be compounded in lenses that lack an internal focusing mechanism, because their physical length often stretches considerably as the focus distance is reduced.

Unlike regular lenses, the performance of macro lenses in terms of sharpness and contrast at narrow apertures is an important factor. This is because depth of field can be as little as a millimetre or two at the shortest focus distance, so you often need to use a narrow aperture to enable sharpness at more than one specific point on a threedimensional subject. With all this in mind, let’s take a look at the best choices for macro shooting on DX and FX Nikons.

Shoot a spider or garden bug, and it can take on the appearance of a giant alien invader, complete with astonishing fine detail