Prime macro lenses in the ~100mm range tend to be pretty darn good, regardless of who builds them, so competition for the Tamron 90mm f/2.8 is pretty stiff.
Sony 90mm macro not connecting manual#
As a visual cue that you're in manual focus mode, a blue ring around the end of the lens barrel is revealed when the focus ring is slid back to the manual position. We found this much more convenient than the usual small slide switch most lenses use. This lens also has a different way of switching between manual and automatic focusing, which is accomplished by sliding the focus ring forward or back on the lens barrel. In common with other non-IF (Internal Focusing) lenses, the barrel of the Tamron 90mm f/2.8 extends quite a distance (about 2 inches, or 5 cm) as you focus closer. This decreases the working distance by that amount, but may also eliminate the need to use the included lens hood in all but the most extreme flare conditions. Speaking of working distance, for some reason, the front element of this lens is recessed into the barrel about 1.5 inches (~4cm). With the focus limit disabled, the minimum field of view is about 0.87 inches (22mm), with a working distance of about 3.5 inches (~9 cm) from the front of the lens. At a range of ~11 inches from the front of the lens, and mounted on a 1.6x crop factor DSLR, the field of view is about 2.6 inches (67mm). The aforementioned focus limit switch is helpful when you're shooting at subject distances greater than a foot or so, as it greatly reduces the amount of time the camera could spend hunting for correct focus. The plastic construction does help a little with weight too, so this lens doesn't unbalance the camera to the extent some lenses built with more metal might. The Tamron 90mm f/2.8 doesn't rise to the "built like a tank" quality of some manufacturer's primes, but its plastic barrel feels sturdy and solid, and manual focus operation is very smooth.
On our EOS-20D test body, focus acquisition and tracking seemed precise and sure-footed. It doesn't do bad though, taking about 1.8 seconds to slew from closest focus to infinity, or a bit under a second when the focus-range switch on the side of the barrel is set to its "Limit" position (which limits the closest focusing distance to about 10-11 inches from the front of the lens). The Tamron 90mm f/2.8 uses a conventional (as opposed to ultrasonic) motor, so isn't quite as fast nor as quiet as lenses powered by the more advanced technology. This focal length seems to be a nearly ideal one for lens designers to minimize distortion: The most distortion the Tamron 90mm f/2.8 shows just 0.04% pincushion, and average distortion is less than half that value. Shading hits a maximum of only 0.2 EV wide open, and drops to more or less unmeasurable levels at f/4 and higher. On a sub-frame camera, light uniformity is excellent across the board. The Tamron 90mm f/2.8 also does very well in terms of Chromatic Aberration, with low to moderate maximum CA and low average CA.
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