Although Tamron has been producing 90mm macro lenses since the late 1970s, the latest SP AF90mm f/2.8 Di Macro 1:1 lens is the first with Tamron's latest Di (Digitally Integrated Design) technology, which matches the performance characteristics of current DSLR cameras. The new lens features improved coatings that reduce reflected light bouncing off the mirror-like surface of the sensor, thereby ensuring the full colour and contrast ranges in subjects are recorded.
Otherwise the new lens has the same optical configuration as the lens it replaces, with 10 elements in 9 groups. No exotic glasses are included and, like its predecessor, the new lens provided a 1:1 magnification ratio at a focused distance of 29 cm. Weighing only 405 grams, it is lighter than many competitors while being similar in length and diameter.
Tamron's latest SP AF90mm f/2.8 Di Macro 1:1 lens, shown without the supplied cylindrical lens hood. (Source: Tamron.)
Usable with both film and digital SLRs (including DSLRs with APS-C sized sensors, where it covers a focal length equivalent to approximately 135mm in 35mm format), this lens will also work as a portrait lens. The focal length is ideal for head and shoulders portraits with a full-frame DSLR and for head shots on cameras with smaller sensors.
Most of the lens barrel is made from black polycarbonate, although a metal mounting plate is provided. Despite its relatively light weight, the build quality of the 90mm macro lens is good, which is to be expected of Tamron's SP (Super Performance) lenses, which are built to ‘professional' standards.
The front element is recessed almost 4 cm into the lens barrel, protecting it from dust, scratches and sticky fingers. In contrast, the rear element is quite exposed. Both front and rear elements remain fixed during autofocusing, effectively sealing the lens against the entry of dust and moisture.
Near the front of the lens barrel is a 45 mm wide focusing ring with a 25mm wide ridged rubber grip coating. The front of the ring steps down sharply for a couple of millimeters to the inner barrel. Although the front of the lens doesn't rotate during focusing, the inner barrel extends by 52 mm as you move from the infinity position to the closest focus of 29 cm.
Autofocusing appears to be driven by a conventional micro-motor. Switching between manual and autofocusing is done by moving the focus ring backwards (for MF) and forwards (for AF), which engages a clutch mechanism. (With some Sony and Pentax cameras you must also set the camera to the corresponding focus mode.) The focusing mode can be swapped at any point in the focusing range.
Behind the focusing ring is a recessed distance scale with distances in metres and feet. As on most modern lenses, no aperture ring is provided, which means this lens can't be used on older cameras with only mechanical controls. (The Canon version we reviewed has seven contact points on the lens mount to support electronic control of the nine-bladed iris diaphragm.)
Just aft of the distance scale and part way around the left side of the lens barrel is an AF limiter switch with two positions: Full and Limit. The Limit setting restricts the focusing range to between 29 and 40 centimetres and is used to minimise hunting, particularly in low-contrast lighting. The Full setting allows autofocusing to range all the way from 29 cm to infinity, while setting the switch mid-way between Full and Limit spans between 45 cm and infinity and is useful when the lens is used for portraiture.
The lens comes with a cylindrical lens hood, which reverses over the lens barrel for storage. Front and rear caps are also provided, along with a soft carrying pouch. Multi-lingual user instructions are provided on a large printed sheet, which is folded many times and difficult to open for reading. We suspect many purchasers will bin it in frustration before discovering the critical aspects of using this lens (a booklet would have been infinitely preferable).
Handling
We conducted our tests of this lens on the EOS 5D, the standard body we use for testing all lenses of this type. The mounting plate attached to the body positively and securely and the lens felt nicely balanced and comfortable to use.
Like most macro lenses, this lens is usually easier to operate when the camera is tripod-mounted. This gives you more flexibility with aperture and enables you to shoot with slower shutter speed settings and maximise the depth-of-field in subjects.
However, thanks to its adequate working distance, it is also usable when the camera is hand-held - as long as the subject is relatively still. Higher ISO settings are required to provide small enough lens apertures to give some depth-of-field in subjects - although depth-of-field remains very limited at apertures as small as f/11 with very close subjects.
We found the clutch mechanism on the AF/MF switch to be rather tight. The advantage of this was that shifting between auto and manual focusing was very positive. However, after pre-focusing in AF mode then swapping back to manual focus for fine-tuning we found the focus often shifted slightly. It's not a major problem, but one users should be aware of.
Autofocusing was generally quiet for a motor-driven lens and reasonably fast for a macro lens. Provided the focus limiter switch was used correctly, hunting was mainly restricted to low-contrast subjects in poor lighting. In bright lighting, focus was usually quick to lock on.
Manual focusing was very smooth and the focusing ring turns through almost 180 degrees, making accurate focusing relatively easy.
Performance
Imatest showed the review lens to be a very good performer, although not up to the standard of the Canon EF 100mm f/2.8L Macro IS USM lens we reviewed earlier this year - which is more than twice the price. In addition, resolution was comparatively low at the widest lens apertures, although the overall contrast from this lens was relatively high, giving an impression of above-average sharpness.
Resolution climbed steadily upwards to a peak at f/5.6 before trending slowly down. As expected, the differences between centre and edge resolution were minimal, confirming the lens has the excellent flatness of field you would expect from a true macro lens.
Diffraction reduces resolution from about f/11 on and it's probably best to avoid apertures smaller than about f/14. The graph below shows the results of our tests.
Lateral chromatic aberration was negligible to low, as you would expect from a true macro lens. In the graph below, the red line marks the boundary between ‘negligible' and ‘low' CA.
Distortion was also negligible and this, again, is a characteristic of a good true macro lens. We found slight vignetting at the widest apertures but it was gone by f/4, another expected characteristic. Bokeh was as attractive as you would expect from a high-quality macro lens, both at wide apertures and with the aperture stopped down, as is evident in the sample images below.
Buy this lens if:
- You want an affordable macro lens that delivers sharp images at mid-range aperture settings.
- You want competent mechanical performance.
- You want a lens that requires no readjustment when you fit filters.
- You'd like a lens that delivers attractive bokeh.
Don't buy this lens if:
- You need a general-purpose lens.
- You require built-in image stabilisation.
- You're not prepared to use a tripod for critical macro work.
IMATEST GRAPHS
Based on JPEG files taken with the Canon EOS 5D:
SAMPLE IMAGES
Taken with the Canon EOS 5D:
Vignetting at f/2.8.
Vignetting at f/4.
Camera on tripod; 1:1 reproduction of a postage stamp; ISO 200, 1/5 second at f/6.4.
Camera on tripod; ISO 200, 1/60 second at f/2.8.
Camera on tripod; ISO 200, 1/30 second at f/4.
Camera on tripod; ISO 200, 1/15 second at f/5.6.
Camera on tripod; ISO 200, 1/8 second at f/8.
Camera on tripod; ISO 100, 1/25 second at f/5.6.
Camera on tripod; ISO 100, 1/12 second at f/5.6.
Camera hand-held; ISO 800, 1/60 second at f/8.
Camera hand-held; ISO 800, 1/30 second at f/11.
Camera hand-held; ISO 400, 1/60 second at f/5.6.
Camera hand-held; ISO 400, 1/100 second at f/11.
Camera hand-held; ISO 400, 1/125 second at f/4. (Subject measures approximately 4 mm overall.)
Camera hand-held; ISO 400, 1/60 second at f/5.6.
Camera hand-held; ISO 640, 1/83 second at f/4.
Taken with the lens on the Canon EOS 40D; camera hand-held; ISO 800, 1/100 second at f/8. (Subject measures approximately 4 mm overall.)