Not quite a 50mm lens, the Tamron SP 45mm f/1.8 Di VC USD gives a more generous viewing angle of 51 degrees rather than the more usual 46 degrees on a full-frame body. Suffice to say, there’s very little in it. Like the Tamron SP 35mm f/1.8 Di VC USD, the bigger 45mm combines a fairly fast f/1.8 aperture rating with 4-stop stabilisation. It’s smaller than Sigma and Zeiss’s 50mm lenses and more lightweight; at 540g, it’s two-thirds the weight of the Sigma and a little over half the weight of the Zeiss. It’s still almost twice as heavy as the Canon 50mm f/1.4.
Build quality is considerably better than in either of the Canon 50mm lenses, including the EF 50mm f/1.8 STM, and not far off that of the Sigma. Like the Tamron 35mm, this lens features extensive weather-seals and a fluorine coating on its front element, to repel water and greasy fingerprints and to aid easy cleaning. It has a ring-type ultrasonic autofocus system that’s both fast and consistently accurate, beating that of the Canon 50mm f/1.4 lens on both counts. As usual with this type of system, full-time manual override is available in Single AF mode.
Centre-sharpness is much better than from the Tamron 35mm lens in the aperture range of f/1.8 to f/2.8, although both lenses perform well towards the edges and corners of the frame. Defocused areas look very soft and the crossover between sharp and blurred areas in images has a nicely smooth transition. Bokeh continues to impress when stopping down a bit from wide-open shooting, helped by a well-rounded aperture based on nine diaphragm blades.
Having a quality lens as lightweight as this really helps when travelling or shooting for an extended day, and handling is also a pleasure thanks to the large, smooth focusing ring and the large AF and VC switches. Minimum focus distance is also shorter than you might expect on a lens like this at 0.2m, further expanding the lens’s versatility.