Ricoh GRX/A12 Review: 18. Photographic tests (Lens): Digital Photography Review

Studio Tests - 33mm F2.5 Macro GR lens

NOTE - These tests use RAW files converted with ACR 5.6 for the MTF50 calculations, and as we've noted elsewhere in this review, this appears to be a sub-optimal combination. This means that comparisons with other lenses should be viewed with caution - we suspect the Ricoh's numbers are being underestimated.

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Ricoh were keen to stress to us the quality of the 'GR' series 33mm F2.5 Macro lens, and our tests show that their confidence in the optics is well-founded. There's very little to complain about here at all - the corners are slightly soft wide open, but this unlikely to be a problem in practice, as these areas of the frame will probably be either out-of-focus, or simply pictorially unimportant, anyway.

Sharpness	Wide open at F2.5, sharpness is very good in the center and across most of the frame, just dropping off somewhat towards the extreme edge and corners. Close the aperture down a couple of notches to F3.3, though, and the corners sharpen up nicely. Performance is then impressively high and even across the frame, until diffraction starts degrading the image at small apertures. As usual on APS-C apertures smaller than F16 should probably be avoided, unless extreme depth of field is essential.
Chromatic Aberration	Chromatic aberration is very low indeed, with just-about-noticeable red/cyan fringing at the corners. If you shoot in JPEG, the camera will automatically correct this anyway.
Falloff	We consider falloff to become perceptible when the corner illumination falls to more than 1 stop less than the center. At a maximum of 2/3 stop wide open, there's really nothing to see here.
Distortion	Distortion is (as we'd expect from a lens designated 'Macro') very low indeed, at a near-imperceptible 0.4% barrel. In the shooting menu you've got the option to turn on distortion correction, but this doesn't have any effect (it appears to be a body function which has been implemented for use with other camera modules).

Macro Focus

	Macro - 40 x 26 mm coverage 106 px/mm (2686 px/in) Distortion: Low Corner softness: Excellent Equiv. focal length: 50 mm

The A12's macro mode lets you focus from a minimum distance of 7 cm (30 cm in standard mode) which is approximately half life-size. This is not quite as good as the best dedicated macro lenses for SLRs, but still allows for interesting macro photography (photographer's skills permitting). Image quality at such short subject distances is still excellent but the macro mode is slightly let down by its Auto Focus performance. It's very slow, tends to hunt and frequently requires several attempts to lock on, making manual focus the better solution for this type of photography.

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