Lens review

Pentax smc D FA 100 mm f/2.8 Macro WR

18 March 2011
Arkadiusz Olech

3. Build quality

This chapter we start in a traditional way – by comparing the tested lens with its competitors. In the following chart we gathered different macro class 2.8/100 lenses without image stabilization. Small dimensions and weight of the Pentax stick out immediately in this group. It’s interesting that exactly the smallest Pentax is the only weather-resistant lens here (WR), and its outer barrel is made of metal.

The photo below shows how small the Pentax smc D FA 100 mm f/2.8 Macro WR really is – the lens is positioned next to the Canon EF 100 mm f/2.8L IS USM. Both lenses feature exactly the same parameters and both cover full frame. The Canon has image stabilization build in; it features an ultrasonic autofocus motor and doesn’t change its dimensions but even after taking these facts into account the difference in their sizes remains really huge.

Pentax smc D FA 100 mm f/2.8 Macro WR - Build quality

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Immediately you can notice delicate build of the lens along with its solidity; it clearly refers to the style of older manual devices. At first sight you get the impression that we deal here with something different than a typical, contemporary lens. In fact, it is a distinctive feature of Pentax products – if it doesn’t have untypical focal length or aperture, it has at least an untypical appearance or dimensions. When our market is being inundated with identical or almost identical products which often differ only in logo on their casings and has been produced in the same factory, such an originality is really a nice variety.

Pentax smc D FA 100 mm f/2.8 Macro WR - Build quality

The lens starts with a metal mount inside which you can find an immobile rear element, 3 cm in diameter. The mount is surrounded by a red gasket. It is a very interesting choice of colour, which, along with the blue ‘WR’ letters on the barrel breaks the black-and-white monotony of the rest of the casing in a really original way.

Pentax smc D FA 100 mm f/2.8 Macro WR - Build quality

The further part of the lens, painted black, is made of metal like the mount. First we meet the ‘PENTAX 100’ inscription and right below ‘MACRO WR’, informing us that we deal here with a fully-sealed macro lens. On both sides of the inscription there is some ribbed area to ensure a better grip. On the other side there is another inscription ‘Assembled in Vietnam’. In this price segment we would definitely prefer to see ‘Japan’ instead. What can be done, though – this globalization and cost- cutting tendencies…

In the next part of the casing we find a depth of field scale for f/32 and f/16 aperture values. It is expressed in feet and metres and additionally provides information about the magnification ratio. The scale is moved by a manual focus ring. The ring is comfortable as it features a ribbing area 13 mm wide. It works very efficiently. Running through the distance scale takes about a 310-degree turn. Such a value is sufficiently high to ensure very precise settings. It’s a pity, though the producer didn’t implement any focus limiter which would make the focusing mechanism work faster in some specific usages.

The movement of the ring makes two noticeable (i.e.audible) things occur. First you can hear quite distinctly some unpleasant wheezing. I don’t know whether it is a norm or an affliction of this particular specimen but it is not an effect pleasing to the ear. The second thing concerns extending of the front elements system by about 46 mm. When we pass to the minimum focus the lens gets longer and, what’s interesting, the tube which support the front elements system is made of plastics. The front element is a bit over 3 cm in diameter and it hides inside the tube almost 2 cm deep. It is surrounded by a non-rotating filter thread, 49 mm in diameter.

When it comes to the optical construction of the lens, we deal here with nine elements positioned in 8 groups. Inside you can also find a circular aperture with eight diaphragm blades which can be closed down to f/32.

Pentax smc D FA 100 mm f/2.8 Macro WR - Build quality

The buyer gets both caps, a hood and a stiffened case made of fabric.

Pentax smc D FA 100 mm f/2.8 Macro WR - Build quality