Tamron 45mm f/1.8 Di VC USD SP

SLRgear Review
September 18, 2015
by William Brawley

Tamron, the third-party lens manufacturer primarily known for their zoom lenses, is doing a re-vamp to their "SP" line of higher-end lenses, starting with a pair of new full-frame ƒ/1.8 prime lenses. The 45mm ƒ/1.8 lens is just shy of the typical "standard" 50mm focal length, giving this short portrait prime a touch more wide-angle perspective.

In addition, this lens, as well as the new 35mm ƒ/1.8 VC, is not only weather-sealed (including a gasket around the mount), but also features Tamron's Vibration Compensation image stabilization system -- making this the world's first 45mm full-frame lens with an ƒ/1.8 aperture and image stabilization.

As with the new 35mm ƒ/1.8 VC, the 45mm affordably priced at $599 and ships with a lens hood and SILKYPIX Developer Studio 4.0 image editing software.

Sharpness
Despite the bright ƒ/1.8 aperture, the Tamron 45mm ƒ/1.8 VC is quite sharp wide-open, on both full- and sub-frame cameras. The centers aren't quite tack-sharp wide open, but are still surprisingly sharp for the aperture. The corners are, understandably, a bit soft at ƒ/1.8, but not objectionably so, on both full-frame and APS-C cameras.

As with many lenses, stopping down a bit sharpens things up considerably. On both sensor sizes, the sweet spot for critical sharpness was around ƒ/4-5.6, though ƒ/8 is still very sharp. The centers are tack sharp, and the blur characteristics -- as shown in our graphs -- are nearly flat across the entire frame. As you stop down further, to the ƒ/16 minimum aperture size, we see some very minor image softness creep in due to diffraction, but overall the effect is very minimal.

Excellent sharpness from this lens all-around.

Chromatic Aberration
Chromatic aberration is well-controlled and stays at a pretty consistent level throughout the aperture range on both full-frame and APS-C cameras. Average CA on a full-frame camera measured right around three hundredths of a percent of frame height, which is very low. On a sub-frame camera, CA measured slightly higher, with a slight increase in average CA past ƒ/4. In real-world shooting, we see some evidence of CA in the far corners on high-contrast edges in the form of cyan and magenta fringing, but at an amount that would easily be correctable in photo editing software.

Shading ("Vignetting")
Although Tamron touts the new 45mm ƒ/1.8 as having virtually no vignetting with "well balanced and optimized" overall illumination across the frame, vignetting was in fact an issue with this lens, particularly on full-frame cameras. As can be expected, the greatest vignetting was found wide open (a bit below a full 1EV of light falloff). And while vignetting decreased as we stopped down it was still measurable at ƒ/4 and beyond (around 0.25EVs).

On a sub-frame camera, vignetting becomes less severe, but doesn't disappear entirely, with ~0.4EVs of falloff at ƒ/1.8. Stopping down lessens the vignetting, though from ƒ/2.8 onwards, vignetting remains steady -- though very low -- at around 0.1EV.

Distortion
With a focal length around the 50mm mark this lens is a prime (ha!) choice for portraits, so it's nice to see very minimal geometric distortion on both sensor sizes. The lens is not completely devoid of distortion, but it's extremely minimal: Around +0.13% of barrel distortion on a full-frame sensor and around +0.06% barrel distortion on an APS-C sensor.

Autofocus Operation
Autofocus is achieved using a ring-type ultrasonic motor, known as "Ultrasonic Silent Drive" in Tamron marketing-speak. In our tests, the AF was indeed nearly silent and felt accurate, but autofocus was on the slow side. It felt slower to us than Canon's USM lenses, and in our testing, the Tamron took over one second to rack through the entire range from minimum focusing distance out to infinity -- this is most likely due to its short close-focusing distance, which means the lens has a lot of distance to rotate when focusing.

Manual focus is also available, of course, with a dedicated AF/MF switch located on the side of the barrel. The lens also offers full-time manual focus override of the AF system simply by rotating the focus ring.

Macro
Though the lens is not designed for true macro photography, it does have a rather impressive minimum focusing distance of 11.4 inches with a magnification ratio of 1:3.4 (0.29x). Far from a macro lens, that's for sure, but the Tamron 45mm ƒ/1.8 allows for very nice close-up shots (which can result in some very pleasing, highly blurred backgrounds).

Build Quality and Handling
Despite being a full-frame lens, having a wide ƒ/1.8 aperture, and featuring built-in image stabilization, the Tamron 45mm ƒ/1.8 is surprisingly lightweight, at around 540g (~1.2lbs.) for the Canon-mount version. The Nikon-mount version is slightly lighter, according to Tamron, at 520g. A Sony full-frame A-mount version is also available, though since Sony's full-frame SLT cameras and now also their full-frame "Mark II" E-mount cameras all have sensor-shift image stabilization, the Tamron 45mm ƒ/1.8 for Sony does not include Vibration Compensation. (Presumably, the Sony-mount version weighs even less than the Canon or Nikon version, but Tamron has not provided that spec yet.)

Mounted to a larger Canon DSLR - in this case a Canon 5DS and 5DS R - the lens balanced well on the camera. With a diameter of around three inches, the lens feels rather large, but the lightweight design makes up for bulk.

The entire lens feels very solid, with a lightweight aluminum metal barrel construction finished in a smooth matte black (and a new characteristic matte gold ring around the lens mount). The mount itself is also metal and features a rubbery gasket for weather sealing against the camera body. The lens barrel elsewhere is also physically sealed against dust and moisture, and the internal focusing design prevents lens "breathing" that could suck in moisture and particulates.

As a prime lens, the external features are relatively simple and straightforward. The lens features one large ridged focus ring, which has a rather long focus throw of about 180 degrees. Having a long focus throw is great for filmmaking as it allows precise control over small focus adjustments. The focus ring on the Tamron lens will rotate indefinitely due to the electronic USM ring-type AF system, though it does have soft stops at either end of the focus scale. The AF/MF toggle sits on the left side of the lens with the image stabilization switch. The lens also features a covered focus distance window, though it lacks depth of field markings.

Inside the barrel, the Tamron 45mm uses a floating element design with a total of 10 optical elements, including two glass-molded aspherical elements and one Low Dispersion element, all situated in eight groups. The lens elements feature eBAND (Extended Bandwidth and Angular-Dependency) and BBAR (Broad-Band Anti-Reflection) coatings to help reduce surface reflections and prevent ghosting and flare. Additionally, the outermost lens elements also include a fluorine coating, for enhanced water and oil resistance, further increasing the lens's performance in difficult conditions.

The lens features a 9-bladed circular aperture diaphragm, which results in smooth, pleasing out of focus backgrounds. The lens uses 67mm filter threads and includes a bayonet-mount petal-shaped lens hood.

Alternatives

With the 45mm ƒ/1.8 VC and 35mm ƒ/1.8 VC lenses ushering in Tamron's revamp of their 'SP' lens lineup, Tamron doesn't have a direct competitor to this 45mm prime in terms of a predecessor model. Other manufacturers, however, offer a number of similar alternatives for the budget-friendly, standard FOV, fast-aperture portrait prime. However, the 45mm ƒ/1.8 VC currently stands alone as the only 45mm prime for full-frame cameras with an ƒ/1.8 aperture and image stabilization.

For Canon users, the long-lived "Plastic Fantastic" 50mm ƒ/1.8 lens was recently updated with an upgraded build, a metal lens mount once again and Canon's new STM focusing motor. Compared to the Tamron 45mm ƒ/1.8 VC, however, the Canon's primary strengths are its smaller size and much lower expensive price. The Tamron lens, despite its $599 price tag, is situated more as a professional- or enthusiast-level lens, and produces much sharper images, even at ƒ/1.8. The Tamron also offers weather sealing and image stabilization, which the Canon 50 ƒ/1.8 lacks.

On the Nikon side of things, they too have their nifty fifty: The Nikon 50mm ƒ/1.8G AF-S. The Tamron, again, takes the nod for sharpness, build quality and weather sealing, while the Nikon gets points -- similar to its Canon counterpart -- for a smaller size and lower price.

For A-mount shooters, Sony also offers their own 50mm ƒ/1.8 prime. The Sony 50mm ƒ/1.8 SAM earns many of the same points for compactness and price as its Canon and Nikon counterparts, however the Tamron bests this lens in sharpness, build quality and feature-set.

All told, perhaps the most apt alternative to the Tamron 45mm ƒ/1.8 VC, given the Tamron's focus as a higher-end, high-quality optic, is the Sigma 50mm ƒ/1.4 Art. The Sigma 50mm ƒ/1.4 Art was designed to such a high standard as to compete with the $4,000 Zeiss Otus 55mm ƒ/1.4 lens. The Sigma edges out Tamron in sharpness, and control of distortion and chromatic aberration while providing a much brighter maximum aperture. The Tamron 45mm will save you almost $500, while adding image stabilization and weather sealing to the mix.

Conclusion
Taking a page out of Sigma's book, Tamron is revamping their higher-end 'SP' line of premium lenses, starting with a pair of fast, ƒ/1.8 image stabilized prime lenses. The longer 45mm ƒ/1.8 VC prime offers an excellent balance of affordable price and image quality. Furthermore, the Tamron 45mm ƒ/1.8 VC, maintain this low price while including lots of high-end features only seen on pro lenses at double the price, such as weather sealing, all-metal barrel construction and fluorine-coated lenses. Add in the as-yet unmatched image stabilization and you have a very compelling lens.

The Tamron SP 45mm ƒ/1.8 VC is a great choice for full-frame DSLR shooters looking for an affordable portrait prime with excellent low-light capabilities and very good image quality.

Product Photos

Sample Photos

• View Sample Gallery Photos on our Flickr page •

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.

Still Life shot

VFA target

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.