Where Are The Lenses?
January 23, 2010
Most DSLRs today evolved from earlier film-camera systems. (Sony’s originally came from Minolta; only Olympus started over from scratch.)
Although lens mounts stayed the same, there was a tiny problem about the sensor. Film cameras shot in a 24 x 36mm format. But making digital sensor chips of that size turns out to be quite expensive and difficult.
Sensor chips are made on costly, ultrapure silicon wafers, each about 8 or 12 inches in diameter. Obviously, increasing the area of each sensor means fewer of them can fit on the wafer.
With all the steps needed to lay down pixel electronics, it’s nearly unavoidable to get a few random, chip-wrecking defects scattered across the wafer. So the bigger each sensor is, the more likely it is to be ruined by some defect.
These two factors mean the economics of “full-frame” sensors will always be forbidding. You can read more details in a rather informative Canon PDF white paper here. (Take their marketing spin with a grain of salt; just start reading at page 11.)
By Canon’s reckoning, a finished APS-C sensor might cost 1/20th as much as a full-frame one. (That was written in 2006; today’s numbers might be a little different, with 12″ wafers more common. But still, the principle applies.)
So, despite all the wails and begging of enthusiast photographers, there are still only a handful of 24 x 36 mm format digital cameras on the market. A Canon 5D Mk II is $2500. A Nikon D700 is $2400. A Leica M9 is a whopping $7000. A Sony A850 is the “bargain,” at only $2000. These prices are without lenses, of course.
Today’s affordable DSLR models are all based on smaller, APS-C sized sensors. The origin of that cryptic name is irrelevant today; but it simply means a chip slightly under 16 x 24 mm.
There are dozens of APS-C models on the market, starting from the low $400’s—and that price includes a kit zoom. Megapixel counts range from 6 to 14 Mp. While it would be misguided to push pixel counts higher than that, the current models give satisfactory images even when set to ISO 800.
It seems apparent that APS-C is today’s sweet spot for digital-camera value. And because of the chip economics I mentioned, that is not likely to change anytime soon.
So let me (finally) get to my real point.
Where are the lenses?
Back in the olden days of 35mm SLRs, the “kit lens” was typically a 50mm standard one, with an aperture f/1.8 or so. A photographer more serious about low-light shooting could buy the f/1.4 version. You could get a nice inexpensive wide angle or portrait lens of f/2.8 or faster.
So, where are the equivalents for APS-C?
Lots of old lenses designed for film bodies are still being sold. But when used on APS, these make you to pay a premium in size, weight, cost, and maximum aperture. Cameramakers have dragged their feet on creating interesting, new, fast lenses dedicated to APS-C bodies.
Today, of course, the default is to offer zooms instead of primes; the APS-specific lenses you are able to buy are mostly zooms.
Yes, zooms are convenient. But you typically lose two f-stops of light-gathering power. Some say modern image stabilization gives back those two stops—but that’s true only if you don’t care about viewfinder dimness, or blur when the subject moves. Zooms are larger and heavier than primes, too.
The normal lens for an APS-C camera would be about 32 mm (48e on a 1.5x sensor; 52e on a 1.6x Canon). The only camera maker so far to “get it” with an APS-specific normal is Nikon, with their 35/1.8. Sigma sells a 30mm f/1.4 in various mounts—but it’s mystifying that they’re all alone in that market.
For portraits we generally want a nicely-blurred background—meaning we’d like a wide maximum f/stop. This is especially true when using a smaller sensor, because depth of field increases slightly compared to 24 x 36 format. So where are the APS-specific portrait lenses, at f/2.0 or faster? In the range of 60 to 70mm (giving 90-105e), there’s only this Tamron—intended more as a dedicated macro lens.
Yes, there’s oodles of 50mm’s around, recycled from the film era. Canon is well known for their “thrifty 50” —which apparently they’re able to knock out for a hundred bucks, despite it covering a larger format. Why on earth should APS-specific lenses be more expensive? The image circle they cover is only 2/3rds the width!
Shooting film, my most-used wide-angle is a 24mm f/2.8. And back in the day, cheap 28mm f/2.8’s were a dime a dozen. But convert that to APS-speak. Are there any f/2.8 lenses of roughly 17mm? Is your sole available choice one chubby $600 zoom? I sure can’t find anything else.
I’ll give credit to Pentax, for creating the widest lineup of APS-specific lenses—including several beautifully-finished primes. But their prices are high, and their widest apertures are really nothing to get excited about.
Finally, lets take a glance at the Micro Four Thirds universe, too. Panasonic’s new 20mm f/1.7 pancake (40e on the µ4/3 sensor format) has indeed made quite a splash.
The test reports are excellent. So I suppose it would be snarky to observe that Panasonic’s 20 just revives a lens style that numerous snapshot cameras offered in the 1970s—and at a much higher price.
So, where are the lenses?