The overall 10mm movement within the AX body is designed to give autofocus with lenses from 15mm to 300mm. By moving the entire film, mirror, shutter and viewfinder assembly backwards or forwards at high speed on ceramic rails, the AX SLR body allows AF with manual focus lenses. When using wide or standard lenses, it is enough to set the lens to infinity and let the camera do the focusing - with 85 to 300mm lenses, mid-distance and closer subjects are best tackled by first focusing the lens to around the right distance.
Macro and extreme close-up subjects call for the camera lens to be set to its closest focus, and in many cases AF is comfortable and accurate. In other cases, however, it hunts or runs out of extension, and for these the Macro mode is provided. This sets the film plane right back as far from the lens mount as it will go, and locks it there. The viewfinder then provides electronic focus confirmation with an optional audible bleep, making the camera fully usable by those with poor eyesight, even for critical macro work.
With the 50mm �1.4 Planar, the extra 1cm permits focusing to around one-third life size on film, just as a 10mm extension tube would do. With the 28mm �2.8 Distagon the effect is more extreme, a scale of around half life size exaggerated by a very close viewpoint.
I tested both lenses at Gilmerton Butterfly World near Edinburgh (photography is freely permitted) and found that for these subjects, and for most flowers, the extra 10mm added to the range of a standard 50mm lens was adequate. The exposure accuracy and colour quality of the natural-light shots which resulted, mostly taken at around �8, was striking. The entire roll from the Contax AX completely blew away other pictures which we shot using two different ringflashes, two other 35mm bodies, and the Minolta Vectis S-1 APS SLR. Technically, depth of field might be a bit lacking and the hand-held shutter speeds were not short enough, but the beautiful natural light rendering given by the Planar could not be matched. I say this despite the fact that all our other shots were taken on 50mm or 100mm dedicated macro lenses. Even the �1.7 Planar is hardly intended to be used at macro distances, let alone the �1.4. This leads to an important consideration.
I doubt that this is so. Even before AF lenses were needed, designers were claiming that internal focusing and floating elements greatly enhanced performance. Old-fashioned 'move the whole lens' focusing was already on the way out - and Zeiss themselves used these new ideas, providing a manual floating group to improve close-up field flatness on the 40mm CF Distagon for Hasselblad, and building automatic floating elements into several Contax wide-angles.
When the AX autofocus is used, the benefits of these floating elements are lost. To keep the precise corrections of an 18mm Distagon, you should disable AF and work manually. This applies even more to macro lenses and zooms.
Zeiss can not have it both ways - they can't claim optimum optical performance for a focusing system which over-rides the finely corrected internal focusing and floating elements of their best lenses.
Any photographer who has ever copied a slide knows that an exact 1:1 (life size) limit is frustrating. We need macro lenses which go just beyond, to 1.1:1 - 10% magnification. With the AX's extra 10mm extension, this is enabled. Slide copies can be made which clear the 1.5mm all-round crop given by DIN standard slide mounts.
That 10mm can also come in very useful when you're trying to focus on a close subject with a 135mm, 180mm or tele zoom.
The Contax AX must return to its makers - we can't keep their sample for ever - so at this stage I can't test it with the 60mm macro. You lot out there will have had no trouble in understanding how useful an extra 10mm variable extension tube, body-integral AF and viewfinder/audible focus confirmation will be to macro workers. Combined with the absence of external lens movement during AF - no risk of an AF 50mm macro suddenly hunting forwards and alarming your subject, which constantly happened with the other cameras during our butterfly shoot - these factors make the bulky, expensive Contax AX one of the best SLRs ever produced for macro work.
- David Kilpatrick
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