Tamron 35mm f/1.8 Di VC USD SP
Lab Test Results
November 3, 2015
by Andrew Alexander
Tamron has upped the ante in the fast-prime market, taking a note from Sigma's book by creating new versions of its SP series of lens that have a premium feel. Tamron's lenses include image stabilization, something of a rarity in wide prime lenses.
The Tamron 35mm ƒ/1.8 Di VC USD SP is designed to fit a full-frame sensor, and is available currently in Nikon and Canon mounts, with plans for a Sony mount in the works. On a Nikon sub-frame camera like the D7100, the lens will produce an effective field of view of 52mm, and on a Canon, around 56mm (both in 35mm film terms).
The lens ships with a hood, is available now for around $600.
The Tamron 35mm ƒ/1.8 Di VC USD SP offers decent results for sharpness when used at its maximum aperture of ƒ/1.8, and improves remarkably when stopped down. When the lens is employed on a sub-frame camera like the Canon 7D, the results are slightly better in the corners because the lens is trained on a smaller capture area.
The "worst" results are found with the lens mounted on a full-frame camera like the Canon 1Ds mkIII, where corners are slightly soft at ƒ/1.8; there is a sweet spot of sharpness in the center. Stopping down even just a third of a stop to ƒ/2 shows significant improvement, but one needs to go to ƒ/2.8 to get better results for sharpness: at this point it's getting to the point where it's almost tack-sharp across the frame.
At ƒ/4 and greater, the lens offers its sharpest performance, essentially, tack-sharp across the frame. This trend continues to ƒ/11, where we begin to note the impact of diffraction limiting, but even at ƒ/16, the impact is only slightly noticeable.
The Tamron 35mm holds up well against chromatic aberration - there is some visible, mostly in the corners and in areas of high contrast - where it manifests as color fringing, in the cyan-magenta spectrum.
With the Tamron 35mm ƒ/1.8 mounted on the sub-frame Canon 7D, there isn't evidence of any noteworthy corner shading. With the lens mounted on the full-frame Canon 1Ds mkIII however, it's much more noticeable - at the ƒ/1.8 setting, the extreme corners are one full stop darker than the center of the frame. This is reduced as the lens is stopped down: a half-stop at ƒ/2.8, and a third of a stop at any other aperture.
As you'd expect with a wide-angle lens, there would be some barrel distortion, but what's unexpected is how it's been minimized by Tamron. In this case, the worst you'll see is +0.3% barrel distortion, and that's with the lens mounted on the full-frame Canon 1Ds mkIII.
The Tamron SP 35mm ƒ/1.8 Di VC USD uses a ring-type USD (Ultrasonic Silent Drive) that allows the lens to focus very quietly. It's not as quick to focus as other lenses, but we'll attribute that to the wider throw it has to cover; it takes about a second to go through the entire range of focus. There is a slight amount of lens extension as the lens focuses to its closest point, but not so much as to interfere with any attached 67mm filters. Attached filters will not rotate during focusing operations.
Tamron has made sure to note that the lens focuses very close - closer than other lenses in this category. Specifically, its minimum close-focusing distance is 20cm, just shy of 8 inches, and it offers a decent macro performance of 0.4x (1:2.5).
Build Quality and Handling
The Tamron SP 35mm ƒ/1.8 Di VC USD SP presents a new fit and finish for Tamron lenses, offering a smooth, satiny finish with just a hint of texture. A new "SP" badge is present to seal the deal. Inside the lens there's an exotic layout of lens elements: 10 elements in 9 groups, including 1 LD (Low Dispersion), 1 XLD (eXtra Low Dispersion) and 2 aspherical elements. The aperture is made up of 9 curved diaphragm blades, to ensure excellent bokeh. Tamron has provided a windowed distance scale, measured in both metric and imperial, but there is no depth-of-field scale or infrared index.
The layout of the lens is fairly simple: two switches, one for enabling / disabling autofocus, and one for enabling / disabling the Vibration Control (VC) system. The Sony-mount variant of this lens won't come with VC, because Sony cameras have image stabilization built-in, and the two systems conflict. It's also worth noting that there is a rubber seal at the camera-mount side of the lens.
The manual focusing ring is quite pleasant to use on this lens: it's about an inch wide, with a deep ribbed rubber texture. There is a generous 180 degrees of focusing throw - great for manual focus - and either end comes to a soft stop to let you know that focusing further won't do anything.
The Vibration Control image stabilization is a definite perk for this lens, as most manufacturers don't include it for a prime lens: however, with digital cameras being used more and more for making movies, having built-in stabilization is very useful indeed. In our testing, the system offers around three stops of hand-holding improvement: check out our IS Test tab for greater detail.
The lens ships with the HF012 lens hood, which is a petal-shaped, bayonet-mounted hood. The interior of the hood is ribbed to improve resistance to flare. It's about 1 3/4 long, and it will add about 1 1/2 inches to the overall length of the lens when it's mounted.
Canon EF 35mm ƒ/2 IS USM ~$600
Canon's the only other manufacturer to offer a lens with image stabilization in this category, and it performs very well. However, the Tamron is a bit sharper than the Canon, and is more resistant to chromatic aberration; as well, it offers a wider ƒ/1.8 aperture (though this is only a third of a stop). Since the lenses cost about the same, you get slightly more out of the Tamron.
Nikon 35mm ƒ/1.8G AF-S Nikkor ~$600
Though we've yet to test this lens, it's Nikon's full-frame affordable 35mm prime. The other option from Nikon is the 35mm f/1.4, which tips the scales at three times the price. Unlike the Tamron, the Nikon 35mm f/1.8G is not stabilized, but it is competitively priced similar to the Tamron.
Sigma 35mm ƒ/1.4 DG HSM "A" ~$900
Sigma's offering in this category offers very sharp results, even wide open at ƒ/1.4, at a competitive price; it also fares very well with CA and distortion, but presents some significant corner shading.
There's a lot to like in the Tamron 35mm ƒ/1.8 Di VC USD SP. One usually expects the third-party manufacturers to produce lenses that are less expensive than the name-brand manufacturers, but in this case, Tamron has produced a superior lens and priced it for at least as much as its Canon equivalent, making it an attractive option indeed.
The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Tamron 35mm f/1.8 Di VC USD SP
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