The Digital Sensor: A Guide to Understanding Digital Cameras

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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evolving and improving, and whatever megapixel assumptions we talk about today will certainly become invalid and outdated in the near future.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.