Lens review

Pentax smc DA 50 mm f/1.8

22 December 2012
Arkadiusz Olech

3. Build quality

Almost every self-respecting producer wants to have cheap 50 mm lenses with an aperture near f/1.8 in their line-up. As you can imagine we had no problems with a comparison which we presented in the following chart. Still you should remember that only the Pentax and the Sony have been designed for smaller sensors. Them and the Canon are made of plastics (mounts included). A metal mount you can get buying products of Nikon and Minolta which is already out of production. You can notice that the Pentax is physically the lightest and the smallest of all the group, presented here.

In the photo below the Pentax 1.8/50 is positioned next to the Sigma 1.4/30 and the Canon 1.8/50 II.

Pentax smc DA 50 mm f/1.8 - Build quality

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The tested lens starts with a mount made of plastics which is surrounded by an immobile element of the barrel, also plastic, with an embossed inscription “Assembled in Vietnam”. Right next to it you can find contacts and an aperture pusher.

A rear element is 23 mm in diameter and it moves along the whole optical system of the lens. When the sharpness is set at the minimum distance the element is more or less 1 cm deep inside the barrel. If you pass to infinity the element is almost on the same level as the edge of the mount.

Pentax smc DA 50 mm f/1.8 - Build quality

Looking from above at the proper body of the lens you can find the “PENTAX 50 mm” inscription with fine ribs flanking it – their task is to ensure a safer grip. On the left there is a plate in the middle of the ribs with the “smc PENTAX DA” notice which indicates using multilayer SMC coatings and suggests we deal here with a lens optimized to work with digital detectors.

The next element is a narrow, green ring behind which there is an immobile fragment of the barrel with the name and the parameters of the lens. Further on you see a manual focus ring, 8 mm wide, covered with fine ribs. Its movements are surprisingly smooth and it is well-damped. It compares very favourably to the rings of its rivals as it actually allows you normal, comfortable work. What’s more running through the whole scale takes a turn through 200 degrees which is a very good result, ensuring precise settings.

The lens ends with an immobile, smooth part of the barrel, not looking like something you can attach a hood to. However inside it features a non-rotating fliter thread, 52 mm in diameter.

The front element is 29 mm in diameter and, as we’ve already mentioned, it moves along the whole optical system of the lens.

The build quality of the Pentax 1.8/50 is similar to that of lenses produced by Canon and Sony. The Pentax stands out because its manual focus ring is actually functional. In the case of the Canon and the Sony these rings are rather dummies as you can’t use them in a normal way. The Nikkor 1.8/50G boasts the highest build quality in this group as it features a metal mount.

Pentax smc DA 50 mm f/1.8 - Build quality

When it comes to the optical construction we deal here with 6 elements positioned in 5 groups. It is a quite typical layout, repeated also in the case of the Canon, the Sony and the Minolta. Inside you can find an aperture with seven diaphragm blades which can be closed down to the value of f/22.

In the segment of plastic 1.8/50 lenses the producers don’t give you a lot of accessories and Pentax is not an exception to that rule. You get just caps in the box.

Pentax smc DA 50 mm f/1.8 - Build quality