|
Tamron AF 90mm f/2.8 SP Di macro (Pentax) - Review / Lab Test Report |
|
Lens Reviews -
Pentax
|
|
Page 1 of 2
Review by Klaus Schroiff, published February 2008
Lens kindly provided for testing purposes by Norbert Warncke!
Introduction
Tamron has always been a major player in the macro photography market and their star
in this segment is the highly popular the Tamron AF 90mm f/2.8 SP Di macro. It is a distant
relative of the initial Tamron 90mm f/2.5 Adaptall model from the early 80s. It received
several incremental improvements over the years and the current Di (Digitally Integrated)
version has been optimized for today's image sensors. The lens belongs to Tamron's SP
(Super Performance) line up indicating a professional grade performance similar to
Sigma EX or Tokina AT-X Pro lenses - on paper at least. The Tamron is a full format lens -
used on an APS-C DSLRs the field-of-view is equivalent to about 135mm here. The
primary application of the lens is, obviously, macro photography but it's not limited to
that - infinity focus remains naturally possible so it's also an interesting option for -say-
portrait photography.
The Tamron is a comparatively light-weight lens but Tamron managed to keep the build quality o
n a high level. The focus rings operates exceptionally smooth. Typical for most
macro lenses the length of the lens increases substantially when focusing towards closer distances.
The front element does not rotate so using a polarizer is not problem.
The package includes a soft-bag and a lens hood but the latter is really a strictly optional
accessory item because the front element resides deeply recessed within the lens body (about 2cm
below the front) making cleaning efforts a little cumbersome.
Switching between manual- and auto-focus is possible via a focus clutch mechanism by moving the
focus ring back and forth in conjunction with the camera's AF/MF switch. Typical for most
conventional Pentax mount lenses the Tamron has no internal AF motor and relies on a slotted
drive screw operated by the camera. As a result the AF generates a moderate degree of noise.
The AF speed is Ok but unless you use the lens for macro photography it is a good idea to take
advantage of the focus limiter in order to avoid excessive AF hunting throughout the focus range.
| Specifications |
|---|
| Equiv. focal length | 135 mm (full format equivalent) |
| Equiv. aperture | f/4.2 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 12 elements in 9 groups |
| Number of aperture blades | 9 |
| min. focus distance | 0.29 m (max. magnification ratio 1:1) |
| Dimensions | 72 x 97 mm |
| Weight | 405 g |
| Filter size | 55 mm (non-rotating) |
| Hood | Barrel shaped (supplied) |
| Other features | Focus clutch mechanism. Focus limiter. |
|
