In this article, we look at the Macro lens, providing a guide to what it is for, and how it works
A camera lens that enables you to reproduce your subject on the film or sensor frame pretty close to, or even larger than, its actual size is a macro lens. Confusingly, a macro lens is also referred to as a ‘micro’ lens – particularly by Nikon with its Micro Nikkor macro optics.
Macro lenses are often identifiable by small and sometimes recessed front elements. To focus closely, many macro lenses need to physically extend dramatically, although more recent macro lens designs use internal focusing and don’t change in length. A macro lens is used for close-up photography popularised by amazingly detailed images of insects, for example, but also for photographing flower details and all manner of tiny objects, both for aesthetic and practical purposes.
A true macro lens must reproduce 1:1 or actual life size on the film or sensor frame – but many macro lenses and other lenses with a ‘macro’ mode don’t achieve this goal. However, between manufacturers there is no solidly agreed definition of what a macro lens is. Some say it is a close-focusing lens, but there are macro lenses, normally of telephoto focal length, that focus relatively far from the subject. Usually a macro lens will focus to infinity and be useful for general photography and some macro lenses double as great portrait lenses. But macro lenses are also used with extension tubes or bellows to enable closer focusing, and this prevents being able to focus on distant subjects.
Sophisticated macro lenses employ floating lens groups that progressively correct optical imperfections that appear when the lens nears its closest focusing point. The optical specification of a macro lens also becomes distorted as it is focused closer and closer to the subject, as the necessary lens extension becomes extreme. When focusing close, the effective focal length gets longer, which gives a narrower working aperture and a corresponding loss in brightness. Thankfully, when using in-camera exposure metering, modern cameras make this fairly transparent, but when doing things manually, expect to have to compensate for some strangeness.