Still in the grip of Prime Lens Mania (“prime” means no zoom), I ventured into the wilds of eBay and picked up a Pentax smc 21mm P-DA F3.2, in theory the perfect companion to the 40mm “Pancake”. With illustrations and a cat-blogging bonus.

Very few pictures are worth anywhere near a thousand words, but this pair might be worth a couple hundred. The same scene from the same position, a corner of our back garden. The 21mm wide-angle above, the 40mm pancake below.

Garden scene shot with Pentax smc P-DA 21mm
· · ·
Garden scene shot with Pentax smc P-DA 40mm

The theory, I guess, is that the 21mm is for carrying around a city or a mountain and shooting views and vistas; the 40mm for taking a garden or party and shooting flowers and faces. One of these renditions looks a whole lot more like what I think I see than the other. What do you think?

I’ve decided that while the prime lenses may be (in theory) better glass, and a little faster too, my eyes aren’t good enough to care about the differences, other things being equal, between a prime shot and a zoom shot. The thing about the prime lenses is that they remove a distraction, encourage you to leave one hand off the camera, compose with your body, and shoot faster.

After dinner, our two cats and some neighborhood became involved in complex maneuvers involving the porch roof and the pear tree (the crows hate the cats, and say so noisily). I had the pancake on and the camera handy.

Cat in tree in the evening sun


Comment feed for ongoing:Comments feed

From: Janne (May 24 2007, at 23:52)

That is exactly the reason for me to prefer primes. It's a usability problem - a zoom adds another degree of freedom, and another control to operate. Which seems to be enough to overload my capacity to operate the camera without losing focus on what I am trying to do with it. I suddenly spend a lot of cognitive capability operating the camera rather than thinking about composition.

That said, I invite you to play a bit with the 10-17mm fisheye zoom. It's a zoom, yes, but way too much fun to skip :)


From: Matthew (May 25 2007, at 06:38)

I have the 21mm and love it. My favorite lens, though the 50mm f1.4 comes close. With another adventure on ebay you can find the Zenitar 16mm f2.8 Fisheye in the Pentax mount. It is an all manual lens but is on the cheap at around $125 USD. That one is great fun too.


From: Lenny (May 25 2007, at 10:02)

That last photo looks great.

Of the same scene shots, the first is more interesting, probably closer to what you would see, but look at the way the lens warps that tree in a circle!

I guess that "wide angle look" can be desirable, though. Whenever I shoot family, they always ask why I'm coming up so close to them. I think shooting people with a wide angle makes for a warmer, less Victorian sort of portrait.


From: Tim (May 25 2007, at 10:59)

Lenny: No, that's the way the tree's really shaped. Check out the lines of bricks to the left of the tree, straight as an arrow, and the porch railing. The optics are actually pretty remarkable.


From: Chaz Randles (May 25 2007, at 17:49)

The human eye has a focal length around 17mm. Unless there is something very, very strange about your eyes, you *should* get a visual image closer to the 21mm shot. If it is different, it's a software issue. Consider an upgrade :-)


From: Lenny (May 25 2007, at 21:53)

My bad. Indeed the bricks are straight. Is the tree so noticeably curved in a straight-on shot (or when using your eyes, for that matter)?


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