Underexposed

The top two SLR makers have released relatively minor firmware revisions for three cameras, Nikon's higher-end full-frame D3 and D700 and Canon's prosumer-grade EOS 40D.

The fixes generally address rare and unusual problems. One notable fix for the D3 and D700 is for a problem which, as Nikon describes it, "in extremely rare cases, resulted in noticeable black dots in images captured with Long exp. NR (long exposure noise reduction) in the shooting menu set to On." Canon fixed a black-dot issue of its own with the EOS 5D Mark II earlier this month, but Nikon's issue sounds rarer.

Forthwith, the release notes:

The top four SLRs in DxO Labs' current rankings.

(Credit: DxO Labs)

It's not a surprise that the Nikon D3X, the company's brand-new $8,000, 24.5-megapixel SLR, tops DxO Labs' sensor performance test. What is a surprise is the margin by which it leads its rivals from Canon and Sony.

When the French firm unveiled its DxOMark Sensor benchmark test last year, Nikon's D3 was the top scorer at 80.6, a composite number that represents various performance features. Very close on its heels were Nikon's D700 at 80.5, Canon's EOS-1Ds Mark III 80.3, and later Canon's 5D Mark II at 79 and Sony's Alpha A900 at 78.9.

All those cameras were close, but the D3X stands apart with a score of 88. The result shows how much ground Nikon has made up on Canon, which has dominated high-end digital SLR technology.

The Leica M8, the company's first digital rangefinder camera, costs $5,500 without a lens.

(Credit: Leica)

Leica Camera, the German manufacturer of high-prestige but high-price photography equipment, has replaced its top executive, Steven Lee.

"The supervisory board of Leica Camera AG today removed Steven K. Lee as member and chairman of the board of management of Leica Camera AG with immediate effect," the company said in a brief statement Friday.

The board also named Andreas Kaufmann to be chairman of Leica Camera's board of management until February 28, 2009. He and Andreas Lobejaeger will lead the company jointly, the company said.

Leica was an influential brand in the 20th century, pioneering the use of 35mm film and supplying cameras to notable figures such as Henri Cartier-Bresson. However, the company has had some missteps making the transition from film to digital photography.

Leica has a cultlike following for its equipment, and the company sets prices accordingly. The M8, its first digital member of its decades-old M family, costs about $5,500 with no lens. And though its core components are upgradable, the price tag for a new shutter and LCD cover upgrade announced recently is $1,775--about the price of an entire Nikon D300 SLR.

According to a Leica representative quoted in Amateur Photographer, one of Kaufmann's first priorities will be to "review all options for the M system's future."

In an interview earlier this month with Amateur Photographer, Lee hinted that Leica is working on an M8 upgrade that would give it a full-frame image sensor, which is the size of a 35mm film image. Leica's M8 today, as well as most entry-level and midrange SLRs, use sensors about two thirds that size.

(Via 1001 Noisy Cameras.)

It looks like Canon's intermediate-size APS-H sensor line, found in the 1D Mark III SLRs used by photojournalists, may be at the end of its life span.

A silicon chip wafer from Canon can fit only 20 full-frame sensors, and there's lots of wasted real estate.

(Credit: Canon)

The sensor is larger than the APS-C sensors used in mainstream Canon SLRs such as the EOS-40D or the new Canon EOS Rebel XSi, but it's smaller than those in a 1Ds Mark III or 5D, which is the size of a full frame of 35mm film. With Nikon now selling its first full-frame model, the D3, and Sony planning to launch its own full-frame competitor by the end of 2008, I have been curious if those developments meant momentum is shifting toward full-frame. Accordingly, at the Photo Marketing Association trade show, I asked Chuck Westfall, technical adviser for Canon USA's professional products marketing division, about the future of APS-H.

He didn't say anything definite (click here for the full Westfall Q&A), but it's hard to feel optimistic about the format's future. Westfall said the only advantage APS-H has over full-frame is price. And although that's significant, I can't help but notice that Nikon's full-frame D3 is a strong competitor to the 1D Mark III that largely matches its price.

"When we started it at the time, the idea was to compete against APS-C. In that respect it was successful...We've had a good, long run with APS-H," Westfall said. "Going forward, it remains to be seen whether it will continue to be a desirable format. We're not ready to say it's over."

With a rosier future for full-frame cameras, it's not clear to me that anyone will really miss APS-H if it goes extinct.

Chuck Westfall

(Credit: Canon)

With Nikon showing that price doesn't need to be as much of an issue, the photojournalists who are the core market for the 1D Mark III could fare just fine with a full-frame model designed for their high-speed, low-light needs--the 1D Mark IV, perhaps. And for those photogs on the NFL sidelines who might like APS-H's slight telephoto effect, there could be an equivalent to the Nikon D3's DX crop mode that captures only central pixels from the sensor.

For background, there are some good reasons to employ different sensor sizes. Larger sensors of a given megapixel count permit larger pixels that do a better job distinguishing the signal of incoming light from electronic noise in the sensor, so photos have fewer speckles, colors remain more true, and cameras work better in low light. But large image sensors cost a lot more to build.

In the compact camera domain, there are multiple image-sensor sizes in use, but customers rarely know which because the lens is matched to it. In SLRs, though, where lenses are interchangeable, sensor size makes a difference. Lenses behave the same way as in the film era with cameras equipped with full-frame sensors, but the field of view is cropped more narrowly with APS-H and APS-C.

Because of this field-of-view crop factor, the field of view is 1.3 times narrower on an APS-H camera than a full-frame camera and 1.6 times narrower on an APS-C camera.

So for example, a 50mm lens on a full-frame 1Ds Mark III has the same field of view as a 38mm lens on an APS-H 1D Mark III and a 31mm lens on a Rebel XSi.

For telephoto shooting, smaller sensors are generally OK, in effect amplifying the ability to reach distant subjects. For wide-angle lenses, though, the arrival of SLRs with sensors smaller than full-frame initially posed problems. Now, though, camera makers have released new lenses with shorter focal lengths to cover the wider field of view.

Update 12:21 p.m. PST: Mike Baird, Ask.com's first vice president of engineering but now an avid camera buff, is one photographer who expects his 1D Mark III to be his last camera to have a sensor smaller than a full frame.

"I thoroughly expect the sub-35mm sensors to go away in the pro market," Baird said. "The APS-H 1D Mark III has replaced all of my APS-C cameras...I'd like the 1Ds Mark III, but I'm spending all my money on lenses."

Update at 8 a.m. PST on February 7: Westfall's title at Canon has changed and been duly noted.

LAS VEGAS--Two's company, three's a crowd, and Canon's Chuck Westfall is a lot less lonely these days.

Canon once was the sole camera company offering a digital SLR whose sensor is the size of a full frame of 35mm film, a technology that can increase the performance advantage and price penalty that SLR cameras already have compared with compact cameras. In November, though, Nikon began selling its full-frame rival, the D3, and last week Sony said it will launch its own full-frame competitor by the end of 2008.

Chuck Westfall

(Credit: Canon)

Westfall is a camera tech guru and the technical adviser for Canon USA's professional products marketing division. In his 25 years at Canon, he's amassed an encyclopedic knowledge not only of official camera specs but also deeply buried engineering details.

Westfall shared his opinions about the full-frame market and other camera trends during the Photo Marketing Association trade show here. He also discussed fuel cells to replace batteries, flash memory technology, OLED displays, and geotagging.

Talking tech might sound like fun if you represent the company that leads market share both for compact cameras and in the higher-end SLRs, but Westfall also has had to deal with unpleasant autofocus trouble that's afflicted the company's $4,500 photojournalist-oriented EOS-1D Mark III during some shooting conditions. A quality and reputation problem is the last thing a camera maker wants for a model aimed squarely at the professional photographer market that Canon dominates but that Nikon is aggressively courting.

Though Canon is repairing affected 1D Mark III models and has issued a firmware update, the issue still hasn't gone away: Rob Galbraith, the photographer and consultant whose tests brought the problem to light, still believes the 1D Mark III's predecessor has better autofocus, and he reported Monday that Canon is working on yet another fix.

Read on for Westfall's response to the autofocus issue and other thoughts.

CNET News.com: Sony now has said it'll join Canon and Nikon in offering a full-frame camera--its flagship 24.6-megapixel SLR due to launch by the end of the year.
Westfall: It's quite flattering the other companies have recognized what we've known for years--that full-frame is quite a desirable imaging format. I think the full-frame market is set to expand in 2008. There's no doubt about it.

With Nikon and now Sony adding weight to the full-frame market, what role is there for the in-between sensor size, APS-H? (It's about halfway between the full-frame sensors used in the high-end SLRs and the APS-C sensors use in the top-selling models such as the Rebel XTi and 40D. The APS-H is used in the 1D Mark III and its predecessors.)
Westfall: When we introduced APS-H in 2001 with the original EOS-1D, the idea was to compete against other professional DSLRs with APS-C. In that respect it has been extremely successful. At that point it was about what the competition had to offer. It's only been in the last six months that there has been an alternative. We've had a good long run with APS-H.

Going forward, it remains to be seen whether it will continue to be a desirable format. We're not ready to say it's over.

Is there a unique advantage APS-H has over full-frame sensors besides price? Nikon's D3 is a full-frame competitor to the 1D Mark III at about the same cost.
Westfall: At this point, no. Price would be the only thing.

Do you think you've resolved the 1D Mark III autofocus issue?
The hardware fix and firmware update has effectively brought the camera within our design specifications. Under the vast majority of study conditions, the camera is functioning exactly the way we expected it to.

So is it better at autofocus than the 1D Mark II N (the camera's predecessor)?
Westfall: Overall, yes. The system has a lot more to it. There are improvements to the Mark III's autofocus sensor, with 19 cross-type focusing points throughout the frame compared to 7 in the center for the 1D Mark II N. This is an area Rob Galbraith's tests did not address. And there are a lot more customization settings to be able to tweak autofocus accuracy according to the way you shoot--focus priority versus release priority for example.

That said, we are continuing to investigate. We're not disputing anything Rob wrote--he's made a fair and objective test. We have no argument except that the 1D Mark III is a lot closer (to the 1D Mark II N's autofocus performance) in overall performance than his severe tests indicate at first glance and that he doesn't test the full range of conditions. There's more to it.

Geotagging is a hot subject, and much of the discussion at the PMA show seems to have moved from when it will arrive in cameras rather than whether it will. When do you think it will?
Westfall: The desirability of that feature is quite clear. You can see reasons why--classifying, sorting, and searching photos--especially with the advances in technology starting to appear that is taking advantage of the (location) information. That's why we started putting in the optional capability with the wireless transmitters (accessories available for higher-end Canon SLRs).

How far away is the geotagging era?
Westfall: There's no doubt we'll see cameras with built-in GPS within the next two years, possibly sooner. I'm not able to give guidance regarding Canon specifically.

Are you getting pressure to add geotagging support from Web sites such as Google and Yahoo that enable users to make use of geotagged photos?
Westfall: Mostly we're hearing from the vertical markets--professional, commercial, and industrial applications. And the military.

Some envision geotagging as an aspect of "autotagging," in which a rich set of metadata is recorded when the photograph is taken. It might be possible to combine face recognition with autotagging to label photos automatically.
With our PowerShot line, we started autotagging a year ago. We call it "My Category." It has a total of five or six presets and three customizable tags. When you choose a scene mode, it associates for example a "landscape" tag. It can be done in review, too--you can apply it after the fact. For a camera with face recognition, we know when people are present. This will become much more valuable in the future. Facial recognition is a very powerful feature.

Are there any developments in battery technology?
Westfall: Lithium-ion is still dominant. Battery manufacturers have been able to increase the storage density lately. The Canon Rebel XSi battery has a capacity of 1080 milliamp-hours compared to 720 for the Rebel XTi (whose battery is about the same size).

Is there anything more radical on the horizon?
Westfall: Fuel cells. Within the same physical space, you have maybe twice the capacity as lithium-ion batteries. There's a lot of incentive to deliver that. And it's environmentally friendly--it's disposable and refillable.

Samsung is showing its NV24 HD camera, which uses an OLED (organic light-emitting diode) display. Is Canon planning on making that shift?
Westfall: Yes, definitely. We began exploring OLED several years ago. We showed in 2005 a prototype EOS-5D SLR. It was demonstrably brighter, had better color accuracy, and lower power consumption.

A prototype Canon EOS-5D SLR using a OLED display.

(Credit: Canon)

It's common knowledge that Canon is investing in OLED manufacturing ability, making big acquisitions last year. We have the infrastructure needed to bring this online.

And unlike with LCDs, it means you have more of the technology that actually ships in a camera under the Canon roof?
Westfall: Right. We're looking to implement OLED in all our consumer products: digital still cameras, camcorders, and inkjet printers.

There's a new version of CompactFlash memory cards under development that uses the Serial ATA technology rather than the current parallel ATA. You guys use CompactFlash in your SLRs. Will that technology catch on?
Westfall: It remains to be seen. What drives the market is cost and performance issues and availability. That's one reason we elected to wait until now to switch to SD (memory cards) for our Rebel line. The availability of SD cards is better now than even a year ago, and people are more comfortable with it.

I was interested that the 1Ds Mark III has an SD card slot in it as well as a CompactFlash slot.
Westfall: We actually started that with the 1D Mark II in 2004. We were able to add a second slot without changing the overall size of the camera. Now you see a second slot capability on other cameras.

What's changing in the compact camera market?
Westfall: The pricing on these cameras will continue to decline. It's become a more commoditized market, but it's bigger. The forecast for the next three years is it will continue to grow. CIPA (the Camera and Imaging Products Association) forecasts global shipments of 126 million units in 2010 compared to 93 million last year. The challenge is to continue to expand the feature set in the face of price erosion while maintaining profitability. We've got good technology and the highest level of profitability in the digital camera market.

Who's the top competitor?
Westfall: Sony is a very strong competitor. Once you get past them, there are a lot of other companies in there.

Are you worried about Sony entering the SLR market, too?
Westfall: Between us and Nikon, we've got 90 percent of the SLR market. Sony is only in the 5 percent range so far.

With pricing pressures, will you outsource more manufacturing to outside companies?
Westfall: That's not for us. We've increased our Japanese facility for better R&D and manufacturing. We have some outside manufacturing, especially in the point-and-shoot cameras. But we doubled the capacity of our main camera plant in the last two years. To control costs, we're developing more automation in manufacturing.

The jump from 2 megapixels to 4 megapixels is significant, but the jump from 10 to 12 is less dramatic. Is the megapixel race over?
Westfall: We're trying to upgrade the entire camera. The megapixels rating is only one thing. When upgrading, you have to look at more aspects.

Update 5:40 p.m. PST: Westfall requested a few minor changes to his quotations for clarity, such as changing "they" to "battery manufacturers," and I obliged.

With a Thursday announcement about a flagship SLR due later this year, Sony has become the third manufacturer to bet on the full-frame camera market.

(Credit: Stephen Shankland/CNET Networks)

LAS VEGAS--The heyday of 35mm film SLR cameras is long past, but one foundation of the technology is staging something of a comeback with new help from Sony.

The vast majority of digital single-lens reflex cameras today use an image sensor that's smaller than a full frame of 35mm film, which means lenses behave somewhat differently than on a film camera. For years, only Canon sold SLRs with a full-frame sensor, but Nikon entered the market with its top-end D3 late in 2007. At the Photo Marketing Association trade show Thursday, Sony announced its forthcoming "flagship" Alpha-branded SLR will follow suit.

"We will commercialize this model by the end of this year," said Toru Katsumoto, senior general manager of Sony's digital imaging business group. "This model uses a full-frame size, 24.6 megapixel, CMOS censor with Exmor technology"--specifically, Sony's full-frame sensor, he said.

Sony hopes the company's flagship SLR will appeal to professional photographers, but Katsumoto said in an interview that's not the main thrust for the camera.

"It's not for the real professional," Katsumoto said of the flagship model. "We'd like to make this camera of course for professionals, but also for enthusiasts and high-end amateurs."

Sony's move helps the full-frame remain relevant and perhaps spread it a bit more widely. But don't expect the full-frame format to dominate the way it did in the 35mm film era.

Full-frame economics
It's much more expensive to manufacture larger image sensors. Other SLR makers--Olympus, Pentax, Panasonic, Leica, and Samsung--use smaller sensors only, and Nikon and Canon say their small-sensor camera lines are here to stay. Camera makers also have been selling lenses that are geared specifically for small sensors and that sometimes don't work on full-frame models.

Smaller-sensor SLRs are a much larger market. Of the 2007 SLR market, fully 23 percent cost $600 or less, according to data released Thursday by NPD Group. For comparison, the cheapest full-frame model today, Canon's 5D, costs about $2,100 with no lens.

And chip-manufacturing improvements that could lower the cost of full-frame sensors help with smaller sensors.

"Any advance...would apply to both large- and small-format sensors. If CMOS suddenly got less expensive, then small-format would have an even smaller cost per sensor," said Mike DeLuca, a market segment manager for Eastman Kodak's professional and applied imaging group, which designs both small and very large image sensors.

From entry-level to flagship
That Sony is willing to tackle the difficult economics of the full-frame SLR market with its new Alpha provides further evidence that Sony is serious with its SLR push.

"This year, Alpha will proceed to its main stage," Katsumoto said. "We will address the whole spectrum of digital SLR segments this year ranging from entry-level to flagship."

Full-frame cameras can offer greater sensitivity for a given megapixel count because individual pixels are larger and gather more light. Sony's flagship Alpha, just shy of 25 megapixels, puts pixel count in the driver's seat. In contrast, Nikon's 12-megapixel D3 emphasizes bigger pixels with good low-light performance.

Another advantage of full-frame cameras is that lenses owned by 35mm film buffs work the way they were designed to. Small-frame cameras crop out the outer portions of the frame, making it harder to achieve wide-angle views. That could be relevant for customers who own lenses from Konica Minolta, whose camera assets Sony purchased to jump-start its SLR push.

"Full-frame still has advantages," said InfoTrends analyst Ed Lee. "It'll get you back all the wide-angle viewing."

• Field of view diagram from Digital Photo Professional magazine - A nice diagram showing what kind of focal length is required to get a 47-degree field of view with various cameras, e.g. full-frame, APS-C, medium format, Four Thirds. (Judging by the Four Thirds logo, this might be from that Olympus-led group.)
• Leaked? The Samsung GX-20 DSLR - 1001 Noisy Cameras - Roundup of links to GX-20, presumably derivative of a new Pentax model. would-be photo, specs here: http://www.aronsen.no/default.asp?ArtID=428
• Getty Bolsters Its Web Presence (subscription only) WSJ.com - A longish look at Getty's attempt to remake itself through royalty-free photography, including iStockphoto.
• Washingtonpost.com on snitching photos from Flickr etc. - Bloggers to the rescue? "What's noteworthy in each of these cases, Lessig says, 'is that bloggers, a community typically associated with piracy, are rallying in support of copyright.'"
• OLPC Tells Nigerian Court: We Don't Use LANCOR's Keyboard - Groklaw - OLPC answers the patent-infringment complaint.
• Novell's top lawyer is leaving - Joseph LaSala, who's been involved in litigation with The SCO Group and the controversial patent deal with Microsoft, is headed for Discovery Communications. Novell said deputy general counsel Ryan Richards will take over for now.
• Olympus E-3 Review - PhotographyBLOG - Generally favorable review. Modest jabs about its size--so much for one of the advantages 4/3 cameras have over Nikon and Canon. "The amount of time you'll spend penitently wading through the manual will reward you with some seriously good images."
• ExifTool by Phil Harvey - a photo tag editing utility - Perhaps this will be the way I transfer geotags from one photo to others. Looks like a pretty powerful utility, and it supports DNG and various raw file formats.

Update 4:00 p.m.: I clarified two sentences and added a third to make it clear that Nikon and Canon never forced customers to buy small-frame lenses. Still relevant in my opinion, though, is the practical reality that customers already have and will again.

Rob Gruhl shot this photo with a 12-24mm 'DX' lens geared for small-frame Nikon cameras mounted to a full-frame 'FX' camera, the new D3. The DX lens is designed to shed light only on a small-frame image circle, but the D3 can be set to record on its entire sensor frame. This shot, taken at a focal length of 12mm, shows the portion illuminated with the DX lens.

(Credit: Rob Gruhl)

Canon beat Nikon to market by years with a high-end digital SLR whose image sensor is the size of a full frame of 35mm film. But while Nikon may have been late to the party with its new D3, I think it employed a much smarter approach to a lens compatibility issue.

One of the chief merits of single-lens reflex (SLR) cameras is their ability to accommodate multiple lenses, letting photographers adapt the same camera body to shoot everything from faraway birds to the confined quarters of a small house. It's annoying that one company's lenses generally don't work on another company's camera bodies, but it's even more annoying when a single company's products are incompatible, and the full-frame trend in higher-end cameras has put the spotlight on the issue.

Here's the background. The vast majority of digital SLRs sold today use smaller image sensors measuring roughly 24x16mm that are much less expensive to manufacture than full-frame 36x24mm sensors. Canon and Nikon both have made lenses specifically for these smaller sensors; Canon's small-frame lenses bear the EF-S label and Nikon's are called DX. Although neither company forced anyone to buy these lens lines, many have done so.

One big reason to make small-frame lenses is that wide-angle lenses need to be reworked for small sensors. For example, you need to use a 10mm lens on a small-frame Canon camera such as an EOS 40D to get the same field of view as a 16mm lens on a full-frame camera model such as an EOS 5D. Another big reason is that lenses for smaller sensors can be made smaller and lighter.

For many folks with digital SLRs, having a separate line of lenses for small-frame cameras isn't a big deal. They'll buy a lower-end, small-frame camera, and if they buy a later model, there's a good chance it'll be another small-frame model and their lenses will work fine. But for photographers upgrading to a full-frame camera, the lens compatibility issue rears its ugly head.

Canon shooters can't use small-frame EF-S lenses on full-frame cameras. Full-frame cameras physically can only accommodate EF lenses. Nikon, though, permits its small-frame DX lenses to be mounted on its full-frame FX cameras.

Nikon's approach isn't all smooth sailing. DX lenses are designed to shine light only a small sensor, so by default, a full-frame camera will use only the central portion of the larger sensor, meaning that many pixels are wasted. On the 12.1-megapixel D3, you only get a 5.1 megapixel image. And if you do enable the full sensor to work, in many situations light will only fall on the central pixels anyway, leaving a clear record of the lens' smaller image circle. (The DX-on-FX photo by D3 owner Rob Gruhl above illustrates the effect.)

Nikon's strategy meant that lens compatibility is a bigger issue for professional-level photographers. Its first full-frame camera, the $5,000 D3, has only just hit the market in recent weeks. That means pro-level photographers who wanted to go digital with earlier pro-level SLRs such as Nikon's D2Xs might well have felt no compunctions about investing in small-frame lenses and might have been enticed to do so to get a super-wide-angle zoom, for example.

In addition to the relatively inexpensive "kit" lenses that ship with lower-end SLRs, Nikon DX models include a $900 12-24mm f/4 wide-angle zoom, a $1,200 17-55mm f/2.8, a $600 10.5mm f/2.8mm fisheye, and a $700 image-stabilized 18-200mm f/3.5-5.6 super-zoom that's the company's best-selling lens ever.

Canon, on the other hand, introduced full-frame cameras many years earlier--2002 with the EOS-1Ds--when pros weren't as far along in their transition from film to digital and therefore might have been less likely to have made investments in EF-S lenses. Indeed, one EF-S lens useful in getting full performance out of a small-frame SLR, the 10-22mm f/4-5.6 zoom, wasn't even on the market until 2004.

But the market is different now. Canon introduced the full-frame 5D more than two years ago, and it's now available for $2,100. No entry-level buyer will be interested, but that's within the range of a lot of enthusiasts, and I wouldn't be surprised if a more powerful successor (the 5D Mark II? The 7D?) is announced in conjunction with the PMA photo show in January. This is an obvious upgrade path for people who bought solid small-frame models such as the Rebel XT or 20D.

Unfortunately, it's not just a matter of reworking the lens mount on the 5D successor. The approach Canon chose with its EF-S lenses means they physically can't work on full-frame cameras because the camera's reflex mirror, which flips out of the way when a photograph is taken, would strike with the rearmost lens element or at least a rubber ring that protrudes to protect it.

"The reflex mirror on a full-frame camera would definitely collide with the rubber ring on EF-S lenses if someone managed to jam one on," said Canon spokesman and tech guru Chuck Westfall. Canon is not currently rethinking its approach to small-frame lenses on full-frame cameras, he also said.

Canon stands by its approach of permitting only full-frame lenses on full-frame cameras. "In our view, it's more valuable to preserve a full angle of view wherever possible," Westfall said. "The image circle projected by EF-S lenses is only sufficient for EOS digital SLRs with APS-C format (small-frame) image sensors, so allowing such lenses to be mounted on cameras with larger imaging formats wouldn't be practical."

The "S" in EF-S refers to the shorter back-focus distance separating the lenses' rearmost element and the sensor. "Probably the most important potential advantage of shorter backfocus is smaller, lighter and more affordable lenses," Westfall said. "Case in point: EF-S 18-55mm f/3.5-5.6 is significantly smaller, lighter, and more affordable than a lens of the same zoom range and maximum aperture with full-frame coverage."

Canon has some good engineers and I'm sure it carefully evaluated its options when making small-sensor lenses. Its lens approach probably helped it be the first to market with a sub-$1,000 digital SLR, the original Digital Rebel.

But with full-frame SLRs now dropping in price--potentially even faster now that Nikon is exerting competitive pressure--I think it's too bad Canon didn't opt for a design with better lens compatibility. If you're the type of photographer who might consider upgrading to a full-frame camera, think carefully before laying out nearly $1,000 for a Canon 17-55mm EF-S f/2.8.

Sigma's new 70-200mm f/2.8 lens

(Credit: Sigma)

Sigma announced two higher-end telephoto lenses this week for digital SLRs with smaller image sensors.

One has a range of 70mm to 200mm and the other 50mm to 150mm, but both have a large f/2.8 aperture for faster shutter speeds in lower-light conditions and a hypersonic motor for quiet focusing. The lenses are designed for Canon, Nikon, and Sigma SLR cameras.

The two lenses highlight the growing sophistication of technology for digital SLRs with sensors smaller than a frame of 35mm film. Though Canon and now Nikon sell full-frame cameras, the vast majority of models sold use less expensive smaller sensors. Using these new lenses on a full-frame camera will result in dark corners, a phenomenon called vignetting.

Sigma's new 50-150mm f/2.8 lens

(Credit: Sigma)

The APO 50-150mm F2.8 II EX DC HSM has four super-low dispersion glass elements, a minimum focusing distance of 100cm, or 39.4 inches, and a weight of 780 grams, or 27.5 oz. According to Sigma's Japanese Web site, the lens has a price of 109,600 yen, or about $1,000, and will be available Dec. 22.

The APO 70-200mm F2.8 II EX DG MACRO HSM has two super-low dispersion elements and three extra-low dispersion elements. Its minimum focusing distance is 100cm, its minimum focusing distance 100cm, or 39.4 inches, and its weight 1370 grams, or 48.3 oz. The Japanese site puts its price at 142,900 yen, or about $1,300, with availability on December 22.