June 6, 2010
April 29, 2010
The essential principle of the single-lens-reflex camera is actually quite old. Most of the SLR’s earliest incarnations are long forgotten today; but it’s interesting that the name “Graflex” derives from that brand’s early, jumbo sheet-film reflexes—dating all the way back to the 1890s.
In the middle of the 20th century, 35mm cameras rapidly gained respect and market share. But if you could time-travel back to 1958 and ask photographers how they felt about 35mm SLRs, you might be surprised at how divided and contentious the answers were.
Most would probably admit to the SLR’s advantages—in principle—over the other viewfinder styles common at the time.
There is no offset between the taking lens and some separate viewing lens. The framing of a shot is previewed exactly—which is particularly useful in macro and telephoto work. And the lens’s depth of field can be seen directly on the groundglass (albeit dimly, when apertures are small).
All these advantages might even cause our 1958 friends to proclaim SLRs as the wave of the future.
But keep in mind: At that time, the leading 35mm SLR brand was the Exakta, from Dresden, East Germany.
This was a nicely-finished camera, capable of taking fine photos. But its operation was rather clunky. For those who wanted to shoot quickly and spontaneously (which after all, was the forte of 35mm compared to larger formats), SLRs could not compete with rangefinder cameras. Decades of improvements had brought rangefinders to quite a high level of refinement, and they fully dominated the era’s 35mm marketplace.
Before the shutter opens, an SLR’s mirror must flip up out of the way. But in these early models, it did not drop down again afterward—not until the film was advanced. The resulting viewfinder blackout was disorienting, and made it quite hard to follow action.
Also, for a clear, bright groundglass image, an SLR’s lens ought to be at its widest aperture. But ordinarily, it must then be stopped down to a smaller working aperture before making the exposure. Doing that manually for every single shot becomes kind of a pain. Early SLRs struggled with this problem, and manufacturers created numerous rather half-baked solutions to it.
In retrospect the answer was obvious: just design an instant-return mirror and an instant-reopen lens diaphragm. Yet throughout the 1950s, a puzzling thing happened: All the elements of the solution existed somewhere; yet no camera maker ever put all the pieces together.
Many Exakta lenses used an external, spring-loaded plunger aligned in front of the shutter release; the photographer’s finger pressure on this closed the diaphragm. The Praktina of 1954 (another East German brand) pioneered the first instant-stopdown linkage built inside a lensmount—though needing a separate, manual lever to reset it.
But when it came to instant-return mirrors, German camera-makers had a strange resistance to them. Exakta would not redesign their SLRs to include one until 1966.
An instant-return mirror appeared in the 1954 Asahiflex, predecessor to the Pentax. Several other Japanese brands quickly adopted the innovation. But they still wrestled with the diaphragm problem. Many brands used a mechanism that stayed closed down after the shot, dimming the viewfinder until it was reset.
So, it’s rather understandible that many 1950s photographers found SLRs exasperating—and assumed they would always stay that way.
Finally in the spring of 1959, three new Japanese SLRs were introduced: the 120-film Zenza Bronica, the Canonflex, and the Nikon F. All made the breakthrough of combining the two essential features—the instant-return mirror and the instant-reopen diaphragm.
Although Canon’s first SLR proved an evolutionary dead end, the Nikon F was an instant classic (and its lens mount lives on, in Nikon’s DSLRs today). It cemented Nikon’s reputation as a top-tier camera maker; and it announced the arrival of the Japanese as the world’s new camera-design leaders. And within a few years, the two SLR innovations were practically universal among Japanese brands.
So—how does all this ancient history relate to the current wave of EVIL cameras? (“Electronic Viewing, Interchangeable Lens.”) Well, I believe EVIL stands at a similar crossroads today.*
In principle, we know electronic viewfinders offer certain advantages:
Potentially, they can give a much larger and brighter image than the cut-down reflex viewfinder in an APS-C camera. Histograms or any other information can be overlaid on the live image (and be easily reconfigured, via menu or firmware updates). Depth-of-field preview can be brightened electronically, for easier viewing. And instantly magnifying a portion of the frame eases focusing manually when desired.
Electronic viewing opens up possibilities for unconventional new body designs—ones that might be innovative, less obtrusive, and more easily pocketable.
And in principle, (relatively) larger sensors ought to offer no-compromise shooting at higher sensitivities—say, ISO 800, at least.
A midsized image format, with no reflex mirror getting in the way, should stimulate nifty lens innovations, too—imagine shrunken-down rangefinder-type designs. An f/1.4 normal lens could be half the size of its 35mm equivalent! (If the purpose of larger sensors is enhanced low-light shooting, why not fully capitalize on this?)
But the EVIL cameras of today are, in their own way, 1958 Exaktas.
We are beginning to glimpse the great potential they offer. But all the current implementations are crippled by maddening omissions and flaws.
The Olympus VF-2 is the nicest electronic viewfinder currently available. But EVFs must continue to improve in speed, clarity, and low-light usability before they can replace optical viewfinders entirely. And ready access to magnified focusing is essential—something the Samsung NX10 seems to have bungled badly.
“Faux-SLR” body shapes are boringly unimaginative, and needlessly large.
To date, Micro Four Thirds has only delivered a single camera with adequate high-ISO performance (the Panasonic GH1)—despite trumpeting this as the key performance advantage of larger sensors. (The GH1 also uses the only µ4/3 sensor to allow 3:2 framing without penalty.)
Likwise, the Samsung NX10 gives sub-par high-ISO performance compared to other APS-C cameras, such as those using 12 Mp Sony sensors. Pixel counts higher than this simply become counterproductive.
Only Panasonic has delivered any native EVIL lens brighter than f/2.0—which is inexcusable, considering the wide apertures of cine and TV lenses covering similar image circles. Adapting legacy lenses to EVIL bodies remains problematic, due to µ4/3’s crop factor and Samsung’s NX design choices.
Shooting quickly and spontaneously requires an eye-level viewfinder—the history of cameras has repeatedly shown it. A touch-screen interface may look whizzy, but it splits attention between the camera and subject. Controls need to be graspable and usable by feel, while looking through the camera. We’ll have to see if Sony’s upcoming EVIL system (rumored to be called “NEX”) makes any concessions on this point.
In short, it may be quite reasonable to claim “EVIL is the future.”
But I say, “the future isn’t here yet.”
I am still waiting for 1959.
*(Some prefer “MILC”—Mirrorless Interchangeable Lens Cameras—or even “SLEV”—Single Lens Electronic Viewfinder. But why name a camera after what it lacks?)
February 12, 2010
January and February are months when the air hangs thick with new-camera introductions.
We’re also approaching this country’s wildest Lost Weekend of photo-equipment marketing, PMA 2010, which starts February 19th.
So, it’s the right moment to look our camera industry straight in the bleary eye, and ask the hard question. Are you on drugs?
Regular readers of this blog know my arguments well: Overdosing cameras with millions of teensy pixels is risky behavior—in fact, irrational and damaging.
Not unlike drug abuse.
But to survey the full breadth of this scourge, I’ve needed to pore over DP Review’s specs listings—noting the pixel density of every model introduced since January, 2008. (There were almost 400 in total.)
No doubt I’ve missed some models somewhere, or copied some numbers wrong. But I’ve made a sincere attempt to find out: Which brand has the worst megapixel-monkey on its back?
Here’s how it works:
- Camera models of 35 Mp/sq. cm or more (but less than 40) earn one crack pipe
- Models having 40 Mp/sq. cm or above (but below 45) get two crack pipes
- Any model with 45 Mp/sq. cm or “higher” is awarded the unprecedented three crack pipes.
But a camera maker can redeem themselves, somewhat. All I want to see is evidence they’re entering rehab and doing community service.
- Any model with a pixel density of 5 to 15 Mp/sq. cm subtracts one crack pipe
- A camera having 2.5 to 5 Mp/sq. cm knocks off two pipes
- A model of less than 2.5 Mp/sq. cm expunges three whole pipes.
[Note: Currently, the last category only includes Nikon’s high-end D700 and D3s. The Micro Four Thirds models included are all a whisker over 5 Mp/sq. cm.]
First, we must single out Sigma—Boy Scout among camera makers.
Better known for their lenses, they have a small lineup of cameras using the Foveon sensor, which is 20.7 x 13.8mm.
This makes them the only current camera manufacturer to be 100% CRACK FREE. We may find their products a bit geeky and lacking in social graces, but at least they’re leading the clean life.
But for the others, it’s a grim tragedy. In reverse order of crackheadedness, here is the ranking:
- Ricoh: 2 crack pipes
- Pentax: 12 crack pipes
- Tied, with 24 crack pipes each: Sony and Kodak
I must interrupt here to mention that Sony’s crack score should have been 20 points higher—except that, like an agitated street person muttering “I’m getting my life together!”, Sony somehow introduced eleven different DSLR models in the past two years.
But I’m going to let that slide. Sony has at least admitted a problem. Their new (and unproven) detox plan involves a medication named “Exmor R,” and a risky procedure called “back illumination.”
Sadly, we all know how fragile recovery can be.
- Okay. Back to Nikon: 25 crack pipes
- Fujifilm: 31
- Casio: 34
- Canon: 37
(Canon does earn a special “we’re getting help” mention—for tapering off their S90 and G11 models to a slightly lower dose of 10 mg. Er… Mp.)
- Samsung: 39
Samsung! Snap out of it! There’s still time to go home to your family, bringing more NX-mount cameras. I am speaking to you as a concerned friend.
And finally—we get to the two saddest cases in the whole megapixel ward.
Like many addicts, they always seemed able to hold it together in public. But the numbers don’t lie.
- Yes, Olympus: 54 crack pipes
…and perhaps most shocking,
- Panasonic: 67 crack pipes
Tell me it’s not true. The two leaders of Micro Four Thirds? The upstanding citizens who gathered us all in the church basement, to spread the good news about large chips in compact cameras—living a lie?
It’s tragic. One day, you’re a respected member of your industry. Then suddenly, you’re passed out in a seedy motel, wearing nothing but a frayed terry-cloth robe, surrounded by crumpled marketing plans.
Camera makers: There is still time to clean up, and save yourselves.
February 1, 2010
And now for something completely trivial.
Pentax’s recent “upper entry-level” DSLR, the K-x, has been getting favorable reviews lately. Within its circa-$550 price bracket, it offers a lot of value; in particular, “its high ISO JPEGs are possibly the best of all current DSLRs with an APS-C size sensor” (making it an intriguing model for me).
But marketing being what it is, the K-x is equally well known as the DSLR you can get in different colors. Woowoo!
In fact, within Japan, you can use an online configurator to choose between dozens of different finish options.
Which makes Pentax’s meager color choices for those who live elsewhere rather disappointing.
I won’t be too hard on the white version:
To my tastes, this look is a bit too “dental office.” But there’s a practical argument in favor of it.
A light-colored body won’t heat up as much in sunlight. This is probably healthier for the electronics; and it may even reduce image noise, in a few situations.
Buyers of the white K-x enjoy calling it the “Imperial Stormtrooper” edition.
The navy blue variant seems to be aiming for a metallic auto-body style:
Okay, that’s a very sober, masculine, and tasteful color. Great if you’re a silver-haired attorney, buying a luxury sedan.
But it’s not very, you know… colorful. And painting plastics in metallic finishes just makes them look more plasticky, not less, if you ask me.
As an alternative, what about this?
Now, that ought to be a hit among the outdoors crowd. It works for both tree-hugging birdwatchers and camo-wearing deer hunters. Olive isn’t bad either.
Tan has the same advantage of being a lighter color, but without showing dirt quite as quickly as white. And it gives the nice bonus of reducing the visual “weight” of the camera—making it less intimidating for people photos.
The most questionable K-x color option is the screaming fire-engine red:
Ouch. Okay, that is colorful. But it’s rather garish and conspicuous. And red+black feels very dated to me. Is this some ironic 1980s reference I’m not getting?
Anyway, let’s assume red was supposed to be the “fun & playful” option. How about acid green instead:
Again, it lightens the camera (literally and figuratively), while adding a bit of cheerfulness.
In the end it’s all a matter of taste of course.
But still—if Pentax is already producing so many different colors, who picked out such unimaginative ones?
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?
January 19, 2010
So, you’ve probably gotten the idea: I’m a bit outraged about ridiculous megapixel inflation in point & shoot cameras. But Is this just some theoretical problem? Or does it really make for bad pictures?
My apologies that I haven’t yet given an illustration of what I’m talking about. So let’s take a look at the image below:
Whoa, dreamy! What on earth is going on here? Have I mistakenly substituted a Matisse painting by accident? Is this an image from Photoshop’s “watercolor” filter?
Not at all. This is a 100% crop from a typical compact-camera snapshot. We’re seeing about 4% of the total frame. The original image is here.
(I should be clear that I don’t know the photographer; and I am only singling out this image as being typical for its camera type. This source conveniently includes both the fullsize image and the EXIF data, below the image.)
What’s horrifying is that this photo (as we learn from the EXIF) was taken in what ought to be the ideal situation for a digital compact: Bright sunlight, with the sensitivity setting at a moderate ISO 100.
There is no issue of camera shake, as the shutter speed is 1/500 second. The f/4.6 aperture is within one f/stop of the widest possible (at that focal length), to reduce diffraction.
Yet the image looks JUST TERRIBLE.
Okay, let’s name names here. This photo was taken with an inexpensive camera from Olympus: the FE-26.
So, is Olympus just the crappiest manufacturer ever? Well, I will concede that the lens on this camera seems to be particularly poor. Look at that crazy color fringing!
But when it comes to the smudgy lack of detail, the problem is the same as with every other compact camera today—too many pixels.
The FE-26 is a “12 megapixel” model (actually it’s more like 11.8 Mp) using a 1/2.33″ sensor. This means each pixel is about 1.5 microns wide. When pixels are that small, the random difference in photon counts between adjacent pixels can add quite a bit of noise to the image. To solve this, the camera’s processor chip applies a noise-suppressing algorithm, which unfortunately smears out all the fine detail and texture in the scene.
Admittedly, different camera companies can be more or less clever about their noise-reduction processing. This one looks especially bad, but it nicely illustrates the kinds of artifacts that can result.
But what’s clear is that the surplus megapixels of this camera are certainly not delivering additional image detail. And as you increase the ISO or stop down the lens, quality will only get worse.
As I discussed last time, 1.5 micron pixels are always going to struggle with diffraction blur. The theoretical minimum size for a light spot focused by an f/3.7 lens is 5 microns. Stopping down the lens makes the diffraction blur larger.
You can be certain that somewhere within Olympus, engineers are quite aware of the noise and diffraction problems caused by tiny pixels. But the marketing department steamrollers on, demanding that every year the megapixel spec keeps going up. Olympus’s new FE-47 has 1.4 micron pixels—50 Mp per square centimeter.
This is madness. Higher megapixel numbers are a swindle. They make pictures worse. Stop.
And check out all the other “megapixel madness” posts, too.
January 19, 2010
There is a great article at cambridgeincolour.com about the role diffraction plays in digital-camera resolution.
The issue is that at microscopic scales, the wavelike nature of light makes it act in a slightly “squishy” way. Points of light brought to focus by a lens are smeared out by a certain irreducible amount—even if all lens aberrations are perfectly corrected.
Instead of a sharp pinpoint, light is actually focused into a fuzzy bulls-eye pattern. Its bright center is named the Airy disk, after the British scientist who first described it.
Interestingly, the diameter of the Airy disk is unaffected by lens focal length, or image size; it depends only on the f/ratio of the lens. As you stop down the aperture, a bigger fraction of the light fans outwards from its intended path, and so the wider the Airy disk blur becomes.
With lens aberrations, the opposite is true: they create the most blur at widest apertures. On stopping down, sharpness improves.
So most film-camera lenses give their sharpest images at the middle of the f/stop range—the “sweet spot” where the combined effects from diffraction and lens aberrations are lowest. That’s one way to interpret the old photography rule, “f/8 and be there.”
Anyway, it’s easy to figure out the Airy disk size. The diameter in microns is about 1.35 times the f/number (using the green wavelength our eyes see most brightly). So, for example, the Airy disk at f/4 is 5.4 microns across.
The shocking thing few camera-buyers realize is that these fuzzy blobs are often larger than the individual pixels in a digital camera sensor.
The problem is most egregious in the world of point & shoots. Everyone seems to want the highest possible megapixels, in a camera the size of a deck of cards. There’s no way to do this without making each pixel extremely tiny. While the pixels in a good DSLR sensor might be 5 microns wide, the latest megapixel-mad point & shoots shrink each one to 1.5 microns or less. You start to see the problem.
We need to be a little careful about relating Airy disk size to pixel size, though. Sensor pixels have a Bayer pattern of color filters over them; and the final RGB image pixels are the result of a demosaicing algorithm. Also, every digital camera applies some amount of sharpening. This can, to some extent, counteract the diffraction blur.
But you can’t generate detail that was never recorded to begin with.
My assumption is simply that when the Airy disk fully covers four sensor pixels (as shown above), you have reached the point where diffraction makes additional pixels useless—no additional detail can be extracted. (This is a more generous criteria than many other folks’ reckoning.)
Let’s consider a typical point & shoot. Although its lens might open to f/2.8 at the widest zoom setting, at a “normal” focal length the maximum aperture is more like f/3.7. At this f/stop, the Airy disk is 5 microns across; it would fully illuminate four pixels of 1.7 micron width.
So how many megapixels could you get, if a single pixel is 1.7 microns?
Take a typical P&S chip size of 5.9 x 4.4 mm (a size better known by the cryptic designation 1/2.3″). At 3470 x 2603 pixels, you’d have a 9 megapixel camera.
Adding more pixels will not capture more detail. Neither will improved chip technology—we’ve hit a fundamental limit of optics.
Remember, this is all at the lens’s widest aperture (i.e., the one giving the poorest lens performance). As you stop down from there, the diffraction just gets worse.
Yet today’s models continue their mad race to ever-higher megapixel counts. Ten, twelve—now even 14 Mp are being sold.
This is where I start using the word “fraud.” Customers are being sold on these higher numbers with the implication it will make their photos better. This is simply a lie. All the higher megapixels deliver is needlessly bloated file sizes.
People forget that “full” HDTV is only 2 megapixels (1920 x 1080). Or that a 6 Mp camera can make a fine 8″ x 10″ print. A camera with 2 micron pixels is just about the limit, in allowing you to stop down the lens at all. That means staying under 7 Mp, given typical point & shoot chip dimensions.
And the more important point is this: Shoppers shouldn’t give their money to companies who lie to them.