Sigma 30mm F1.4 DC HSM "Art"
Construction and Handling
On this page we will be looking at the physical construction of the Sigma 30mm lens and how it handles while in use.
The small size of the Sigma 30mm F1.4 "Art" makes it a good fit for virtually all Pentax DSLRs. But the lens weighs in at 435g (just shy of a pound), which may seem like a lot alongside Pentax lenses, as they are typically designed to be light and compact. This is the price one has to pay for a fast F1.4 aperture, which is a powerful feature to have at one's disposal. Even though the front element is relatively small, there's stil plenty of glass inside the lens.
Despite its weight, the 30mm feels well-balanced on the K-3 and K-5 cameras. The best handling is achieved when the lens is paired with either of these bodies, as they are substantially heavier than the lens itself as well as entry-level cameras such as the K-50, K-30, and K-r. With that said, when testing the larger Sigma 35mm F1.4 on the K-50 last year, we were able to look past its weight while in the field. Therefore, we don't think that the 30mm's weight will be a major concern for most users.
One last thing we'd like to mention in this section is that this lens has a 62mm filter thread, a rare diameter which it doesn't share with many current K-mount lenses. So, if you're a Pentax shooter and you plan on using filters with this lens, be prepared to purchase a new set of filters. In the current Pentax lens lineup, only the 18-135mm and 18-270mm zooms have a 62mm filter thread.
The lens barrel is just large enough to allow you to comfortably grip the lens and hold it steadily. The location of the focusing ring is perfect, and manual focusing is therefore a breeze. It is also easy to reach the AF/MF switch with your thumb while holding the lens.
Sigma makes precise manual focusing easy by gearing the focusing ring to increase its throw. The throw is 90 degrees and the focusing ring is stiff, enabling very fine adjustments to the focus setting and minimizing the risk of inadvertent changes to the focus setting.
Note that the focusing ring does not rotate while the AF mechanism is in use, and that the lens does not have to be taken out of AF mode to allow for manual focus adjustments (Pentax calls feature this "Quick Shift").
The Sigma 30mm is made in Japan and has a very good build quality. It doesn't boast an all-metal barrel like the Sigma 35mm, but it still looks and feels like a high-end lens. The barrel design is consistent with that of the other Sigma Global Vision lenses.
As far as external controls go, the list is short: we have the focusing ring, the distance scale, and the AF/MF switch. There is absolutely no play in any of the external components of this lens, which is a testament to its excellent construction.
On Pentax lenses, one normally turns the focusing ring clockwise toward infinity and counter-clockwise away from infinity. Like other Sigma lenses, this 30mm does the exact opposite. There is also no DOF scale on this particular lens.
As can be seen in the image above, the serial number is stamped to the right of the distance scale window. A silver "A" badge on the left side denotes that this is an Art-series lens, and the name of the lens and its filter diameter are stamped below the distance scale.
The trim surrounding the distance scale is made of plastic, as are the filter threads and the hood bayonet mount. The focusing ring is made of metal, and it has a nice rubber finish for easy gripping, though a consequence of this is that it attracts dust more easily.
Rear Ring Detail (1:4)
The small decorative piece of barrel adjacent to the lens mount is also made of metal and has finely-machined grooves like other Sigma "Art" lenses.
Looking at the KAF3 lens mount, we observe the lack of a screwdrive shaft, as this lens only supports HSM autofocus. This means that autofocusing on early Pentax DSLRs (launched before 2006) will not be possible. Another interesting thing to note is that due to its wide diameter, the lens mount flange is considerably wider than what we would see on a genuine Pentax lens.
Additional Product Photos
Click on any of the thumbnails below for a larger image.
The included lens hood is generously-sized, and is therefore effective at blocking out stray light to reduce flare and improve contrast. It does make the lens considerably bigger when mounted, but it can of course be reverse-mounted for easy storage. The equally-scaled photos below illustrate the size of the hood; click to enlarge.
Refer to the photo below to see how the Sigma 30mm compares to the Pentax 18-135mm (left) and Pentax 31mm (right).
Pentax 18-135mm (Left) vs Sigma 30mm (Center) vs Pentax 31mm (Right)
The Sigma 30mm F1.4 "Art" is a well-built lens with good ergonomics and a relatively compact size, especially when compared to the Sigma 35mm F1.4. There's a lot of glass inside this lens to facilitate the F1.4 aperture, and this makes it somewhat heavy compared to similarly-sized lenses with smaller apertures. Apart from this, we found no significant issues with this lens as far as build quality or handling goes. Our only regret is that the 30mm isn't weather-sealed, as Pentax is currently missing a WR normal prime in its lineup.