10 February 2011

My new "80 percent" lens for the K-7

Although the purpose of interchangeable-lens cameras is best fulfilled by occasionally changing the lens, I find that it’s nice to have one lens that will serve for around 80 percent of my shots. The DA16-45 is an excellent lens, but stopping at 45mm made it about a 50% lens for me, and the 55-300 although wonderful was even less in demand. I picked up a 50-200WR a few months back, and despite its cramped range and lesser sharpness (relative to the 55-300, in most opinions) I found it suited me better. It's small and light, give me more consistently smooth bokeh... and stopping at 200mm keeps me from venturing beyond SR's ability to combat motion blur when I play in faint light. I had picked up an 18-55WR for its weather properties, but its range was not much wider than the 16-45, it's inherently slower in most of its range, and its imaging qualities are less highly praised by most users.

In the meantime, Pentax introduced the 18-135WR along with its K-5. I could not bring myself to spend $500-plus on this lens, but it got me to thinking. After a full 20 minutes of thought, I rid myself of the 16-45, 18-55 and 55-300 lenses - in essence swapping them for the 18-135.

What did I gain?

  • A lens that is considered a “kit-plus” lens like
    the 16-45 but with a lot more range
  • A “DC” motor that is nearly silent
  • Rounded aperture blades for better bokeh (though my other lenses may have had that too?)
  • A WR lens that won’t need changing in conditions when WR is needed!
  • Last but not least, a lens that I can use for at least 80 percent of my shots.

And what did I lose?

  • the 16-18mm range, which I really will miss.. but maybe 5-10% of the time
  • a little bit of speed (the 55-300 was f/4 from 55-120)
  • all ability to use the screw-driven focus, should the DC motor fail
  • perhaps a bit of battery life, assuming DC is more of a drain than the screw-drive motor
  • perhaps some sharpness also, relative to the 55-300 (perhaps - we shall see!)
  • and some nice-looking lenses that decorated my shelf :^)

The 18-135WR arrived late on the 9th of February. Wow, what a small package! Compared to the 50-200WR, it is similar in length. The 18-135 is much thicker, using 62mm filters instead of 49mm; the new lens is fairly small but dense. It was getting dim outside so I got in a few snaps, which showed the promise this lens brings: a slight whoosh and it snaps into focus. Given the fairly silent shutter of the K-7, the package is impressively easy on the ears.

I know nothing of DA* lenses - they are the top dogs in the Pentax lineup, weather resistant, often f/2.8 and with SDM motors. They are large, heavy and expensive: three strikes so out of my lineup (for those who need the light grasp and can afford them, I have no doubt of the lens' talents). Many have been ridiculed for SDM motor failures, especially the 16-50. I expect this is fifty lenses out of several thousand, but those with bad motors are loud on most forums - and several have had it happen more than once, which is more ominous still. I therefore venture into motorized lenses with some trepidation, but hopefully the DC system is SDM with a few issues resolved in advance. I'll keep the receipt handy and register soon though.

Like every DA lens I've owned, this one comes with a hood. Not merely a hood but one with a slide-out partition so you can turn a polarizing filter with the hood attached. You can lose the slide-out part though, so some care is needed. The slide is at the bottom of the hood in landscape mode, so if holding the camera vertically the shade loses a bit of effectiveness if you hand isn't covering the small gap. The lens focuses internally so no realignment is needed due to focus. This is the first lens I know of that has the focus ring close to the camera mount, so at some point I'm bound to be confused; I have not run into that yet as an issue. All DA lenses can be manually focused while AF(s) is engaged - if you can find the ring. (Note that DAL lenses are the exception to these DA-specific details: the bargains of the Pentax line, these have plastic mounts, no hoods and no 'quick-shift' manual focus override.)