Minolta AF 28-135mm F4-4.5 A-mount lens review by artuk
|artuk#2822 date: Oct-6-2007|
flare control: 3
|ownership:||I own this lens|
|compared to:||Minolta 24-85 f3.5-4.5|
Minolta 24-105 f3.5-4.5
Sigma 24-70 f2.8 EX
|positive:||Very good image quality|
Classic Minolta colour
Very well built
|negative:||No dedicated lens hood|
4ft close focus
|comment:||Originally launched with the first batch of AF lenses with the Minolta 7000 AF body, this was an expensive lens (Ł350). As with all the first generation AF lenses, it has a metal body, and uses (I believe) glass elements rather than plastic, which would account for its weight of around 700g. It is rumoured this lens was designed by, or co-designed with, Leica, but I do not believe there is any evidence for this. My own understanding was that it was designed and built by hand at Minolta's lens plant in Osaka. It differs in detail from other Minolta lenses as the focus ring is in front of the lens mount, near the body, no doubt making it easier to find than at the end of the zoom. Fingers need to be kept clear as it rotates when the camera drives the AF gear, as it is not clutched. A very wide knurled metal zoom ring fills most of the lens body. Build quality is exceptional.|
Minolta stated at launch that the large front element (72mm) had been designed to give good image quality at 28mm at full aperture. At 28mm and full aperture (f4) image quality is very good to excellent, from centre to corner (full frame). Stopping down one or two stops improves image quality a little, but not by a great deal. It can be used at full aperture with confidence. At the long end, where maximum aperture drops to f4.5 the situation is similar, with good to very good performance fully open rising to very good to excellent about 2 stops down. Intermediate focal lengths are equally strong.
At 28mm, a "macro" mode can be engaged by pulling the macro button and twisting the zoom ring beyond its 28mm limit. The zoom ring then becomes a focus control with a well weighted damped action. In this mode, the lens can focus at a ratio of about 1:4 (not true "macro), but this represents a subject distance mere centimetres from the front element, so care may be needed! The image quality in this mode is extremely good, sharp across the frame even from full aperture.
The lens displays typical early Minolta colour and contrast. Overall contrast is moderate, giving good overall image and edge contrast but without the aggressively high contrast of some modern lens designs. Colour is well saturated, and seems to exhibit that classic Minolta "liquid" colour. This type of image quality is often attributed to good micro-contrast, the ability to handle very fine changes in contrast and colour/tone giving the image a very "real" almost 3 dimentional quality. Leica have always designed their lenses with this in mind, and this may explain the rumours of a Leica design in this lens.
Distortions are surprisingly well controlled for a lens of this vintage and extreme range. There is some barreling at 28mm, though it is not the worst I have seen in a full frame zoom lens. At the long end, there is some subtle pincushioning, but it should generally not cause a problem. This isn't the ideal lens for architectural work at its widest end, as straight lines toward the edge of the frame will display a little outward bowing, but it is usable.
AF speed is surpirsingly good for a lens of this vintage, the AF gearing is reasonably high, and on a mid-range body such as a Dynax 7, AF speed is good and accurate. Unfortunately, the minumim focus distance is around 4 feet. This was not doubt a limitation of the design at the time, the lens undoubtedly having been designed by Minoltas engineers with only a little assistance with computer aided design. Given it's focal length range was quite extreme, the image quality was exceptionally good, and the aperture reasonable, something had to give - and it was focus distance!
Flare control in undoubyedly is biggest weakness. Bizarrely, it was never sold with a dedicate lens hood, though in fairness a hood designed for 28mm would offer no protection at 135mm - just check the hood on the 35-200mm Xi to see! Although I would not say the lens glass itself is especially prone to flare, with a 72mm front element right at the front of the lens, it is easy to get flare when a light source is out of shot but in front of the lens. It tends to be the contrast reducing type of flare than can ruin an image, rather than the more localised type of "sunspot" flaring. There are some internet reports that some examples are more prone to flare than others. The best solution is either to use a hand to shade it when it becomes a problem, or use a rubber collpapsible lens hood that screws into the filter ring (Hama et al make them).
Overall, this is a terrific lens. It may not compare to some of todays high resolution and high contrast lens designs on digital, but the overall image quality is fantastic.