Lens review

Pentax smc DA 15 mm f/4 ED AL Limited

16 August 2011
Arkadiusz Olech

3. Build quality

Usually in this place we compare the tested lens with similar devices produced by the competitors. However, as we mentioned in the introduction, there is a problem with the Pentax smc DA 15 mm f/4 ED AL Limited because it is really difficult to find its immediate equivalent among rival lenses. We are forced to compare it to full frame instruments with a similar focal length and to the Pentax 2.8/14 – the results can be seen in the following chart. Comparing dimensions and weight is really redundant here, though. By definition the Pentax 4/15 is decidedly the smallest and physically the lightest of all presented devices as it is designed, like all small Limited devices, for smaller than full frame sensors.

In the photo below it is positioned next other Limited models – the smc DA 21 mm f/3.2 AL Limited and the smc FA 31 mm f/1.8 AL.

Pentax smc DA 15 mm f/4 ED AL Limited  - Build quality

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The lens, as it befits the Limited series, is made almost completely of metal. Only a bottom inside the bayonet mount, surrounding a rear element, is made of plastics. On that bottom you can see the inscription : “Assembled in Vietnam”. The rear element is 11 mm in diameter which might suggest that , with such a wide angle of view and the size of the detector, we can forget about the telecentricity. In the next chapter we will find out how it influences image resolution on the edge of the frame. During focusing the rear element shifts with the whole optical system but the movement is slight, taking not more than 0.5 cm.

Pentax smc DA 15 mm f/4 ED AL Limited  - Build quality

The casing itself is very typical of new Limited series lenses - shapely, stylish, you really can’t confuse it with anything else. First we get a ring, finely ribbed on the left and on the right, with a silvery inscription PENTAX 15 in the middle. Then we find an immobile piece of the casing on which there is a depth of field scale with markings for every complete aperture value the lens offers so from f/4.0 to f/22.

The rest of the lens’s barrel by and large consists of a manual focus ring on which you can find a distance scale in feet and meters and also a relatively narrow ribbed area. The full turn of the ring takes less than 90 degrees. Its work is smooth and well-damped, really nothing to carp about.

At the very front of the lens there are two small protuberances which, at first glance, seem to facilitate the fixing of a screw-in front cap (also made of metal and padded with black velvet inside). In fact these protuberances are tops of an inbuilt petal-type hood. It’s enough to pull them and the hood extends, shadowing the lens.

It is an interesting solution, with an advantage (handy and easy to use) but also a disadvantage (there might be problems with some filters). The front element, 30 mm in diameter, is surrounded by a non-rotating filter thread, 49 mm in diameter. When it comes to the optical construction we deal here with 8 elements in 6 groups. The producer boasts using one low-dispersion ED glass element and a hybrid aspherical element as well (AL). Inside we can also find an aperture with seven diaphragm blades which can be closed down to f/22.

Pentax smc DA 15 mm f/4 ED AL Limited  - Build quality

The buyer gets two caps and a soft pouch in the box.

Pentax smc DA 15 mm f/4 ED AL Limited  - Build quality