Tamron 90mm macro lenses have long had an excellent reputation. The latest version [introduced in late 2012] is the Tamron SP 90mm f2.8 Di VC USD Macro. The new lens has many features including:
- Optical Stabilization [VC = Vibration Control]
- An ultrasonic drive AF motor [USD] with full time manual focusing control
- Improved sealing against dust and moisture
- Additional elements including two XLD [extra low dispersion] and one LD [low dispersion]
- Internal focusing
- eBAND coating
- Circular 9 blade aperture
Tamron 90mm f2.8 Di VC USD Macro Specifications
Model F004 Lens Construction [Groups/Elements] 11/14 Angle of View [diagonal] 27°02’ [full frame] 17°37’ [APS-C] Aperture Range f2.8 – f32 Maximum Macro Magnification Ratio 1:1 Minimum Focusing Distance0.3m [11.8 in] Working Distance at 1:1 macro 139mm [5.5 in] Filter Diameter 58mm Weight 550g [19.4 oz] Lens Length 114.5mm [4.5 in] Lens iameter 76.4mm Aperture Blades 9 [circular] Supplied Accessories Lens hood Available Mounts Canon Nikon Sony [No VC]
The Tamron 90mm f2.8 Di VC USD Macro is a Di series lens, meaning that it is designed to provide full frame coverage. It can, of course, also be used on crop sensor cameras where it provides the angle of view that a 135mm would on full frame. The lens is available in Canon, Nikon and Sony lens mounts, but the Sony version is not optically stabilized since Sony DSLRs use an in-body sensor shift system to stabilize the image.
The Tamron SP 90MM F/2.8 Di VC USD 1:1 Macro has a semi-matte finish plastic outer barrel with a wide ruberrized focusing ring towards the front. There's an AF/MF switch, though since the lens has full time manual focusing the switch only has to be moved to the MF position when no AF operation is desired. The lens has three focusing ranges:
- Infinity to 0.3m
- Infinity to 0.5m
- 0.5m to 0.3m
The ranges are provided to speed up autofocus in the case when the focus range needs to cycle to lock onto the subject. While the difference between 0.3m and 0.5m might seem trivial, in fact it's over half the focusing range. The focus ring turns though a greater angle to go from 0.3m to 0.5m than it does to go from 0.5m to infinity, so selecting the right focusing range can potentially cut the AF time in half under some conditions.
The Vibration control system [VC] only has two settings, "on" and "off". There are no selectable panning modes.
In common with most Tamron lenses, the focus ring rotates to the left [anticlockwise looking from the rear] to get to close focus and to the right to get to infinity. This is also the usual scheme for Nikon lenses, but is backwards from the way most Canon lenses focus. It's not a problem, but it's something to be aware of.
The Tamron 90mm f2.8 Di VC USD Macro comes supplied with a lens hood and carries a 6 year warranty from Tamron.
Lens Performance
Focusing
The USD AF motor is fast and very quiet. I measured the time taken to focus from closest focus [0.3m] to infinity [or vice versa] in good light on an EOS 7D at around 0.55s. If the focus limiting switch is set to 0.5m to infinity, the time is reduced significantly to 0.22s, so you can see that if you aren't shooting in the macro range it pays to use the focus limiter.
Of course normally the lens just moves from wherever it's focused to the new focus point without cycling through the range. Cycling through the full range only happens if there's some initial focus difficulty, such as might occur in very low light. Normally focus is fast, quiet and positive.
AF works well all the way from infinity and normal focus distance down to 1:1 macro at 0.3m
Vibration Control
The Tamron VC system is effective. At normal focus distances most shots taken at around 1/10s were pretty sharp, which corresponds to around 3 stops of stabilization.
It's important to note that stabilization in the macro range is less effective than at non-macro focus distances. This is true for all simple stabilization systems which compensate for rotation about the horizontal and vertical axes. When the lens is focused down into the macro range, horizontal and vertical translation become important and most [but not all] stabilization systems don't compensate for much movement. Tamron themselves say that �From 3m, the benefits of VC gradually decrease as the focus distance becomes closer�. The Canon hybrid AF system can compensate for horizontal and vertical displacement.
The reason why horizontal and vertical translation becomes important in the macro range is simple. The amount that the image moves on the sensor when the camera is translated by "N" mm is simply "N" x magnification. so at 1:1 [1x magnification], is the camera is moved 1mm, the image also moves 1mm. If the lens is focused at a more normal distance, say 9000mm or 9m [29.5ft] the magnification is approximately 1/100 or 0.01x. If the camera moves 1mm, the image only moves by 1/100 mm
Sharpness at non-macro distances
As you would expect, the Tamron 90mm f2.8 Di VC USD Macro is a sharp lens. Wide open at f2.8 it's very good in the center of the frame and good, but slightly less sharp, in the corners of a full frame image. If you look really closely stopping down marginally improves things and center sharpness probably peaks around f5.6, with the corners showing further improvement all the way though f11.
The images above are 100% crops from test shots with a full frame EOS 5D showing the center and corner sharpness at f2.8 and f5.6. The only processing done to the images was to compensate for the vignetting in order to make the crops easier to compare. It's pretty evident that the lens starts out sharp and gets sharper, with corner quality not far down on that of the center.
Sharpness in the macro range
Normal lenses lose sharpness when close focused because the magnitude of various aberrations increases. In a macro lens the lens elements are automatically reconfigured to compensate for the change in aberrations with focusing distance, so full sharpness can be retained even at the closest focusing distance [0.3m in this case] and at 1:1 magnification.
The Tamron 90mm f2.8 Di VC USD Macro starts out quite sharp even wide open at 1:1 macro, but it does get better as the lens is stopped down. At f4 it becomes a little sharper and peak sharpness is reached between f5.6 and f8. At f11 you can see very slight softening due to diffraction effects which become more noticable on further stopping down to f16, f22 and f32. For maximum overall sharpness, working in the f8-f11 range is best, with f16 still being pretty good if more DOF is required. f22 is certainly acceptable but diffraction softening becomes quite noticeable at f32 and unless you really need the additional DOF stopping down past f22 isn't really recommended if sharpness is a primary goal. Diffraction softening occurs with all lenses at small apertures of course, so this isn't a criticism of the Tamron lens, just an observation. Note that with ALL lenses DOF also becomes very narrow at 1x magnification. At f2.8 the total DOF is around 1/3mm [0.34mm]. Even at f16 the DOF is less than 2mm [1.92mm].
If you want actual numbers I made some measurements using a precision chrome-on-glass target which has resolution patterns down to over 200 lp/mm. Using and EOS 7D and measuring in the center of the frame I saw around 72 lp/mm at f2.8, increasing to about 80 lp/mm at f4 and f5.6. Slight diffraction softening at f8 resulted in a drop to 72 lp/mm which further fell to 64 lp/mm at f11 and 51 lp/mm at f16. For those accustomed to thinking in terms of LPPH [lines per picture height] the peak resolution of 80 lp/mm corresponds to around 2384 LPPH on the EOS 7D. These are very good numbers.
Again the edge sharpness lagged just a little behind the center sharpness, but it peaked around f8 where the edges were pretty close in sharpness to the center.
Distortion
For all practical purposes there isn't any distortion, or to put it another way the distortion was so low that I couldn't get an accurate measurement of it [