Olympus makes an unfeasibly small 17mm f/2.8 pancake lens that measures just 57x22mm and nudges rather than tips the scales at a mere 71g. This 'Premium' class lens isn't quite so tiny but it's still very compact at 58x36mm and 120g. The diminutive size and weight are all the more remarkable considering that this lens is more than a whole f/stop faster, with a widest aperture of f/1.8. It makes the zoom lenses in this test group look positively bulky, and serves as an ideal small, stealthy and understated optic for street photography.
The 17mm focal length is equivalent to 34mm in full-frame terms, and gives a viewing angle of 65 degrees. That's pretty much spot on as a classic wide-angle field of view. The optical path includes nine elements in six groups, including two aspherical elements and one Super HR (High Refractive) element.
It lacks the weather-sealed construction of the 7-14mm and 12-40mm lenses that we've covered so far but this one's still a tough cookie with a metal housing. Whereas the autofocus mechanism is extremely quiet in the two zoom lenses, it's essentially silent in this lens, based on Olympus's MSC (Movie & Stills Compatible) screw-drive system with an internal motor. The manual focus clutch and anti-flare ZERO coatings featured in the 'pro' line zoom lenses are retained.
True to its promise, the autofocus system is extremely rapid for stills, yet glides smoothly between focus transitions when shooting movies, without any noise to upset the audio channel. Sharpness is very impressive throughout the entire aperture range and across the whole image frame, only really dropping off at f/22 due to diffraction. Contrast is similarly sumptuous, even at f/1.8, while this widest aperture is sufficient to blur the background nicely when shooting at or near the minimum focus distance of 0.25m. Any signs of colour fringing or distortion are almost impossible to spot.