Tamron AF 90mm f/2.8 SP Di macro (Pentax) - Review / Lab Test Report
Lens Reviews - Pentax
Saturday, 02 February 2008 22:13
Article Index
Introduction
Analysis

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 length135 mm (full format equivalent)
Equiv. aperturef/4.2 (full format equivalent, in terms of depth-of-field)
Optical construction12 elements in 9 groups
Number of aperture blades9
min. focus distance0.29 m (max. magnification ratio 1:1)
Dimensions72 x 97 mm
Weight405 g
Filter size55 mm (non-rotating)
HoodBarrel shaped (supplied)
Other featuresFocus clutch mechanism. Focus limiter.




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