The Digital Sensor: A Guide to Understanding Digital Cameras
by Wesley Fink on April 21, 2008 1:00 AM EST- Posted in
- Digital Camera
Fast Forward
With digital SLR sales continuing to show record growth in a photographic market whose overall growth is much slower, it should be clear that a lot of photo buyers are selecting digital SLR cameras instead. The reasons many of these new buyers select a digital SLR is because they want better quality pictures than they can get with a point and shoot camera. They may also choose a DSLR for the flexibility and growth potential if they get hooked on the photo hobby.
These are exactly the same reasons buyers chose film SLRs instead of 110 point and shoots in the 70s, and 80s. Those reasons are just as valid in the DSLR market as they were in film, and maybe even more so. Digital sensors, like other electronics, are constantly evolving and improving, and whatever megapixel assumptions we talk about today will certainly become invalid and outdated in the near future. However, it is very clear with today's sensors that the tiny sensors in compact point-and-shoot cameras are reaching the point where higher resolutions are simply being traded for noise. Somewhere around 8-10MP we are finding that higher resolution also generally means higher noise and lower sensitivity.
No doubt this roadblock will be passed with advancements in sensor technology, but today more than 8MP of clean resolution and usable sensitivities greater than ISO 400 are rare indeed in the compact camera market. APS C sensors in digital SLRs, however, seem to be getting better and better at higher and higher sensitivities at ever-increasing resolutions. Pundits are already screaming we are going too far with14MP sensors, but they forget that the smallest 4/3 sensor is still more than nine times greater area than the average compact sensor. There is still a lot of room for growth in resolution.
The other complaint - that lenses are finally reaching resolving limits with higher sensor resolutions - is certainly true with the cheap lenses that were the wunderkind of the developing SLR market. It looks like time for quality optics again as the industry has been skating for far too long in the low demands of the developing digital SLR market.
It also appears that prosumers, the serious amateurs among us, will be facing a difficult decision today and even more so in the near future. The cost of larger and larger sensors has been dropping rapidly, and CMOS sensor development from all the majors is also a factor in lowering costs and increasing resolution. Like it or not Canon and Nikon have already begun segmenting their SLR line into full-frame and APS C sensors. Those who couldn't figure out why Sony was introducing mainly full-frame lenses will finally get their answer later this year with Sony's 24.6MP full-frame flagship model.
Despite the fact that full-frame will be aimed at the top of the DSLR market by Canon/Nikon/Sony, the APS C market does not appear to be in any danger. Developments and new models will definitely continue. Players like Pentax and Samsung seem positively locked into the APS C space with no full-frame peeking around the corner, and Olympus has fought too hard for credibility with 4/3 to start singing a full-frame song. Similarly Nikon, Canon, and Sony will adamantly define the full-frame as pro and the rest of their line as prosumer and entry-level. Nikon may also have struck the marketing chord that will develop with full-frame sensors being touted more for their incredible range of ISO sensitivity than for their higher megapixel resolutions.
The problem is that prosumers lust after pro gear and a prosumer today will have to ask another question in their buying decision for accessories now that full-frame looks like it will be "for real". That question is: "will it work on a full-frame". The current $2000 street price of the Canon 5D and the coming release of the Canon 5D Mark II are making that question an important one for many prosumer buyers. The final street price of the presumer Sony "A900" is also still a mystery, but if it is in line with the Canon 5D, as many expect, then this question in the back of the minds of prosumers will move up-front very quickly.
The purpose of this sensor guide was not to explore every facet of sensor design and performance considerations. Each topic discussed could have been an individual article in its own right with more in-depth discussion of the factors that drive design decisions. Instead, the hope was to provide a framework of basic sensor information to provide a better understanding of the evolution of digital sensors and the types of concerns and decisions that are being made in the market today. We sincerely hope you come away with a better understanding and appreciation of the current digital SLR market, and perhaps of your own digital SLR camera or one you might buy in the future.
Part 2 of this Sensor Series is in the works and many of the images are already in the can. It will take a closer look at the sensitivity range and noise of the most recent sensors in the 14MP, 12MP, and 10MP classes of sensors. A few more cameras are on the way, and as soon as they are prepped and tested we will be sharing more of our findings on the newest sensors in the higher resolution sensor classes.
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bjacobson - Tuesday, April 22, 2008 - link
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aliasfox - Monday, April 21, 2008 - link
When everybody was still on 35mm film, it was impossible to tell whether an SLR shot an image or a good point and shoot/rangefinder style camera. Image noise was a function of the film, and within a certain range, SLRs and point and shoots could reproduce the same sharpness and depth of field. All of that is pretty much impossible these days with the split in sensor sizes.My biggest question is: if camera companies could make a pocketable 35mm/APS sized camera 10 years ago, why can't they make the same pocketable size with a digital sensor? An APS-C sized sensor in a Canon G9-style body shouldn't be impossible, and while it would be expensive, it would have image quality worth the price.
I have a feeling that the companies producing SLRs are just trying to protect their high-margin lens business - a company that's not vested in the SLR side of things could carve out a very solid niche by making a point and shoot with an SLR sensor.
And yes, I know the Sigma DP1 exists, but without a zoom lens and max aperture of F4.0, $800 is a lot to ask...
idealego - Wednesday, April 23, 2008 - link
A lot of it has to do with consumers expecting zoom lenses with cameras. The larger the sensor the larger the lens has to be, especially with a zoom lens. I don't think it's possible to have a decent zoom lens on a pocketable camera with a large sensor (with current technology). This is why the DP1 has these limitations. This is also why a camera such as the Sony R1 has such a large lens compared to other cameras with smaller sensors.However, I'd be quite happy with a fast prime lens on a well-designed, pocketable, large-sensor camera, even if it did have a bunch of downsides to it.
If the DP1 was more refined and had a much faster lens, it would be an awesome camera. Unfortunately, it's rather crude compared to cameras from other leading brands.
Johnmcl7 - Monday, April 21, 2008 - link
"My biggest question is: if camera companies could make a pocketable 35mm/APS sized camera 10 years ago, why can't they make the same pocketable size with a digital sensor? An APS-C sized sensor in a Canon G9-style body shouldn't be impossible, and while it would be expensive, it would have image quality worth the price.I have a feeling that the companies producing SLRs are just trying to protect their high-margin lens business - a company that's not vested in the SLR side of things could carve out a very solid niche by making a point and shoot with an SLR sensor. "
I don't think that's the case at all, film and digital cameras have to be a lot more different than you perhaps appreciate. The Sigma DP1 has had a prolonged and difficult development, while I think that's partially because Sigma are less experienced it's not entirely the story. One of the main problems I believe is the way light hits the sensor, with a digital sensor to work optimally you need to have the light hitting the sensor as straight as possible. Film was more flexible in this sense which made it easer to produce small cameras using comparatively large pieces of film. I believe this was one of the difficulties in producing the DP1 as the lens is very close to the sensor which meant the light is hitting the sensor at very high angles. This is easier on an SLR as the sensor is a reasonable distance back from the rear of the lens (Olympus particularly have made a goal of telecentric lenses) although even the 35mm full frame cameras can suffer from poor corner sharpness.
Also with film you didn't have any low pass or IR filter in front of the film itself which is normally part of a digital camera, I believe the DP1 (as well as the Leica M8) don't actually have an AA filter at all which causes its own problems.
Hopefully other companies will have a go seeing the interest that the DP1 is generating, I think Panasonic who produce a 4/3 sensor and are having little success in the SLR market are in a prime condition to do so. However it's a more difficult task than it seems.
John
Heidfirst - Monday, April 21, 2008 - link
"I have a feeling that the companies producing SLRs are just trying to protect their high-margin lens business "when Kodak got out of doing DSLR bodies (even if they were basically Nikons with a different sensor) they said it was because the profits weren't in the bodies but in the lenses - which of course they didn't make ...
Pentax is supposed to be getting out of compacts because they're becoming a commodity item & hence price-sensitive/low margin.
I could imagine someone like Leica doing what you want though as they seem able to command a significant premium.
aliasfox - Monday, April 21, 2008 - link
Leica's currently tied to Panasonic sensors, and relatively speaking, Panasonic hasn't figured out how to make a sensor that has low noise above ISO 200 yet, regardless of size (otherwise I'd seriously contemplate the Lumix LX-2).Also, while I'm willing to pay a premium for a nice fixed lens camera (I'll consider up to $700, maybe even $1000 for a camera with the right handling, image quality, and features), the market for such an expensive "small" camera is probably pretty small (unless professionals are all clamoring for a pocketable camera as a backup in the field).
Lastly, the Leica name generally commands an even healthier premium than I'm willing (or financially able) to consider...
pinto4402 - Monday, April 21, 2008 - link
The sensor is only half the story. The lens is the other half. This is NOT marketing hype. The difference between consumer kit lenses and pro series glass is easily discernible (even to non pixel peepers). Does this justify the 8X difference in price? I don't know.However, I'm pretty sure that it's not possible to construct a high quality P&S with a great lens that is "pocketable," regardless of the sensor size. Good glass tends to be heavy. Even the old Leica and Contax rangefinders were not pocket cameras. They were compact, but I doubt anyone considers them pocket cameras (unless you're talking about cargo or jacket pockets, and you trust having a $6000 camera hanging out of your shirt pocket). When you add zoom functions to the equation (which is a must nowadays), you looking at some serious IQ trade-offs.
That said, I would be the first in line to purchase a good P&S camera that produces high quality professional grade images.
aliasfox - Monday, April 21, 2008 - link
Honestly, I'll be happy if someone can fit an under 2" thick camera with an adequate (say, 28-112mm equivalence, f2.8 - f4.0) lens and a large/larger sensor. Maybe not even an APS-C sensor - a 4/3" design is already significantly larger than a 1/1.8" sized unit. Olympus, are you listening?The Olympus E-420, even with its pancake 28mm equivalence lens, is too thick to put into a jacket pocket (or crammed into some looser fitting jeans).
I rarely ever take dedicated trips to take photos - so packing a backpack half full of photographic equipment to take a "nice" shot is something I'm loathe to do. But I do go cycling, hiking, and other normal touristy activities where I'd like to be able to bring a camera along...
strikeback03 - Tuesday, April 22, 2008 - link
There was the Sony R1 - APS-C sensor and 24-120 Zeiss-branded lens. Not exactly pocketable, even not having to deal with the registration distances required by an SLR with the swinging mirror. Maybe if you were willing to do something with folded optics you could fit a zoom in a smaller body, but who knows how much of an image compromise that would be.My XT with 28 1.8 does fit in the cargo pocket of one pair of pants I own, but I would rather just have it in a small shoulder bag.