The SMC Pentax-DA 18-270 mm F3.5-6.3 ED SDM super zoom is designed exclusively for digital cameras and only covers the APS-C image circle. This lens is manufactured by Tamron, and thus it is made in China rather than in Vietnam, where the Pentax lens factory is located. It features the same external layout and optics as the Tamron 18-270mm lens currently available for Canon and Nikon.
The lens barrel is made of a composite material (plastic) to very fine tolerances and hardly exhibits any wobbling when extended. There is no zoom creep but the lens nevertheless has a switch to lock the lens at its shortest length (which is at the 18mm setting). It has been our experience that zoom creep may develop over time, but out of the box, this lens doesn't have any.
The lens hood is petal-shaped and has a bayonet mount. It is easy to mount and it can even be reversed for storage, although reverse-mounting the hood can be tedious at times. One Pentax specialty is missing: the hood lacks the removable door that facilitates adjusting a circular polarizer.
The front lens cap is the pinch type and can conveniently be mounted and removed with the lens hood in place. The rear lens cap is of the push-on type.
We do miss quick-shift manual focusing (i.e. full-time manual override), so with this lens you cannot fine-tune focus in autofocus mode by just turning the focusing ring. You must first bring the lens into manual focus mode if you wish to focus manually. This is done with an AF/MF switch on the lens barrel.
Autofocus is by built-in AF motor only. This leaves a handful of the oldest Pentax DSLRs in the dust since they do not support SDM focusing (*istD series, K110D and K100D), but the lens can of course be focused manually with these older cameras.
All-in-all the build quality is outstanding for a consumer zoom. The lack of zoom creep, at least while the lens is new, is encouraging.
The lens is light and easy to hold, and the zooming is smooth, so there isn't much more to ask for from a handling standpoint. The only annoyance is that the hood is a little bit hard to reverse-mount.
Some users will find the lack of quick-shift focusing annoying; this is a manifestation of the fact that this is a Tamron lens. If you spend a lot of time focusing manually, the Pentax 18-135mm does offer quick-shift, so you should consider that as an alternative if you can live without the telephoto reach.
The 18-270mm feels quite balanced in your hands even when zoomed to 270mm. It approximately doubles in length, but this certainly doesn't seem excessive.
In addition to the zoom ring and focusing ring, the 18-270mm only has two additional switches: the AF/MF switch, located on the left, and the zoom lock switch, located on the right.
|The AF/MF switch controls whether or not the focusing ring is locked and toggles the camera's autofocus system. The switch is on the small side||The zoom lock switch can lock the lens at 18 mm focal length so that the lens doesn't accidentally extend when you carry it around.|