Lens manufacturers are a bit cheeky about using the word ‘macro’. They use it to describe any kind of close-up photography, whereas the real definition is a lot stricter than that. In fact, a ‘macro’ lens is one that can reproduce an object at its actual size on the film or sensor. It’s this 1:1 reproduction ratio that defines a macro lens, whereas a lot of the time it’s used to describe a close-focusing mode that doesn’t get anywhere near this magnification.

There are two reasons why you can’t focus this close with everyday lenses. First, there’s a purely mechanical issue. To focus closer, you have to move the lens further from the body, and the closer you get, the greater the distance, proportionally, that the lens needs to move. At its minimum focusing distance, the length of this Pentax lens is doubled. Focusing mechanisms with this kind of range are impractical in everyday lens designs.

The second problem is optical. If you take close-ups with regular lenses you’ll probably notice that the contrast and definition aren’t that hot. You might put this down to the subject matter, focusing errors and the limited depth of field at these distances, but in fact a lot of this general softness is because the lens is at or beyond its optical limits. The pictures produced by this Pentax lens have an astonishing clarity and a ‘bite’ beyond anything you could achieve with an everyday lens.

This is partly because it’s optically optimised for close-ups, of course, and partly because it’s a fairly straightforward fixed focal length lens design. The optical quality it produces isn’t confined to macro shots, though. It produces really crisp, contrasty images at any distance and, in fact, this would make a perfectly good ‘standard’ lens for a film camera. It also works on Pentax’s DSLRs, of course, but here the 50mm focal length equates to around 78mm, so it’s a bit ‘long’ for everyday use, though it might make a good portrait lens.

Our test results show high and exceptionally consistent resolution right from f2.8 to f16. It is starting to fall at smaller apertures as diffraction effects start to take hold, but the fall-off isn’t rapid. This is important in a macro lens, where you’re often going to be shooting at small lens apertures to get as much depth of field as possible.

There’s an awful lot to like about this lens, quite apart from its optical quality. It has a smooth, light focusing action that has enormous travel and allows pinpoint focusing accuracy. With close-ups you’re better off shooting manually, partly because you need to pick your focus point carefully to maximise depth of field, and partly because the autofocus in this case tends to hunt around noisily at really close distances. You can use the lens’s distance scale to focus if you prefer, and there are depth of field markings for f16 and f32 to help you ‘zone focus’.

A macro lens like this opens up whole new worlds of photography, and the Pentax’s optical performance and handling are both excellent. It’s not cheap, although it’s not the most expensive piece of glass either, but it is thoroughly recommended for any Pentax DSLR owner with an interest in the smaller details.

It’s always worth mentioning to check the compatibility of a lens with your camera before purchasing, and this can be done fairly easily online via the manufacturer’s website.

Final Verdict The Pentax 50mm f2.8 macro offers consistently high resolution across its aperture range, but what’s not so obvious from the raw figures is this lens’s amazing clarity and ‘bite’. This zoom lens enables you to do something entirely new with your photography OVERALL

Our lens reviewer, and technical expert, Rod is a veritable photographic encyclopaedia. His illustrious CV has seen him write for many mags, websites and journals.