Okay, I take back what I said about the new Pentax 35mm ƒ/2.4 yesterday. The thing is, Pentax needs a Limited DA 24mm!—badly. Badly. But I won't dwell on that. (Unless I just did.) The thing is, I was wrong about the new lens. Pentax is doing the right thing.
The new lens on the new K-r. This looks giant in the picture (ever notice how relative size just doesn't come through in online illustrations?), but it's going to be quite small and light in reality—the body weighs 21 oz. with batteries and card and the lens weighs just 4.4 oz. That's a total of 720g metric.
About the new K-r: its Mama was a K-x, its Papa was a K-7, and remember that old saying about how every new baby is an attempt to take the best of its parents and create a perfect mix?
Exhibit Two. I doubt all these colors will be available in the U.S. or U.K., but the colors are a clear indication that the lens is meant to be an alternative to a kit zoom on the K-r and K-x. That's the right move.
Exhibit Three: The commenters who said that the price of the lens needs to match the price of the camera. They're right.
As Chris Nelson said in the comments, "I think offering an inexpensive prime lens is a great way to get typical zoom consumers interested in the wonderful world of traditional photography. And, I wouldn't be surprised if this lens performs amazingly well." I wouldn't be surprised either.
So Pentax is encouraging K-x and K-r buyers to experience the pleasures of a matched normal prime that goes with those killer little cameras. That's a move I should approve of. I do.
And a final comment: ƒ/2.4 isn't really slow any more. We need to get out of that mindset, I think. In 1980—recent history for me, since I was alive and an adult then ("history" being anything that happened before you were born)—we didn't even have a truly decent 400-speed color print film. ƒ/2.4 is half a stop slower than ƒ/2, but from what I hear, the K-r will have such good high-ISO performance that shooting at ISO 1600 will come with very little penalty and faster ISOs will be feasible. So we lose a quarter from one hand and gain a dollar in the other; the balance is in our favor. Maybe not relative to the best DSLRs of recent times but certainly relative to the not-so-old film days when many still-current lenses were designed and made. Faster lenses are still nice, but they inevitably come with cost and size penalties that aren't always the right tradeoff.
ADDENDUM: Several commenters have noted a website that has published the block diagrams of the new lens and the old FA lens and that claims they're identical. Here's the post. The two lenses are certainly related, but they're not identical. Right away you can see that element 6 has a larger diameter relative to element 5 in the new lens, and both elements 2 and 5 have greater thickness in the new lens. Furthermore, the specs say that both lenses have 5 groups, and the reproductions of these drawings are so crude you can't even tell which group has the additional airspace—they both look like diagrams of 6/4 lenses. (I suspect elements 4 and 5 are uncemented.)
It's tempting to do so, but you really can't make predictions about lens performance based on cross section diagrams. (All you'd have to do to prove this to yourself would be to test a few of the great variety of almost-identical lenses of similar types—say, Planar-types or Tessar-types.) Very subtle changes in the diameter and degrees of curvature and spacing can affect performance, and of course many factors such as glass type, coatings, and mechanical considerations (baffling, centering, aperture shape, etc.) don't show up in the drawing. Sometimes you can detect shared characteristics typical of design types, sometimes not so much. I am more comfortable evaluating the actual performance of specific lenses. In any event, I wouldn't read too much into crude JPEGs of drawings that show similar arrangements of elements.
Notice any similarity? One is a nondescript single-coated kit lens from the 1970s that can be bought on Ebay for $15; the other is one of the most famous—and expensive—lenses of its type available today.
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Original contents copyright 2010 by Michael C. Johnston and/or the bylined author. All Rights Reserved.
Featured Comment by Wieland W.: "Regarding your addendum, although I agree with you in general, in this specific case I think you should consider the evidence. Please look at the attached image, in which the lens schemes are superimposed in a way to give the same size of the mount. The only difference is a slightly smaller diameter of the elements, which might be due to the reduced aperture."
Mike replies: I understand that. And the two lenses might be identical; the superimposition shows that I was...well, wrong. (How appropriate!) However, what I'm saying is that what we as photographers are interested in is performance, and similar or even identical cross sections are not always a predictor of identical performance. There are too many other factors that are also important.
I think it's wiser to wait for the actual lens, test or try it, and evaluate its actual results, rather than make assumptions based on the block diagram.