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evolving and improving, and whatever megapixel assumptions we talk about today will certainly become invalid and outdated in the near future.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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Johnmcl7 - Monday, April 21, 2008 - link
On page 4:"The Foveon sensor falls between 4/4 and the Canon 1.6 in size and has a 1.7X lens multiplier."
I assume this should read '4/3'
Obvious question is what about Fuji? While I realise they re-use Nikon bodies and lenses, the discussion about Bater and Foveon makes no mention of Fuji's sensor. While it is more conventional than the Foveon, it's not just a bog standard bayer sensor and while Fuji are a minor player, so are Sigma.
For those who are not familiar with Fuji's design, they use two photodiodes at every point one larger and one smaller with the two combined to produce a single pixel in the output image. The idea is that these pair of pixels can capture more extended dynamic range than a standard bayer sensor of the same size. The latest version of this sensor is in the Fuji S5 Pro however it's limited to just 6MP although I can't remember if they still produce 12MP files from this. The S5 itself is basically a Fuji version of the very good Nikon D200 body although Nikon have of course moved on with the very impressive D300.
John
Wesley Fink - Monday, April 21, 2008 - link
Yes, it should have read 4/3 and the reference is corrected. The Fuji S3 was one of my favorite Nikon bodies and the dynamic range was certainly impressive in the studio.We did not mean to slight Fuji, but as one Nikon-mount body with a sensor that hasn't been updated in several years (the S3 and S5 sensors are the same as I understand it) we decided not to include the Fuji since there have been no sensor updates in quite a while.
Johnmcl7 - Monday, April 21, 2008 - link
"We did not mean to slight Fuji, but as one Nikon-mount body with a sensor that hasn't been updated in several years (the S3 and S5 sensors are the same as I understand it) we decided not to include the Fuji since there have been no sensor updates in quite a while. "I can't say I really agree there, given the article more focuses on concept in parts I think the S5 sensor is still relevent as it's something slightly different to the bayer sensor. The article refers to only Bayer and Foveon which implies there is nothing else, I think for completeness even if you don't go into any detail it's still worth mentioning Fuji are doing something else.
Also the S3 and S5 sensor are not the same, while they have the same amount of pixels it appears there's been some slight improvements although clearly not much. To be far to Fuji though, the Foveon sensor hasn't really come on much either - it's gone up very slightly in resolution with some small other changes but that's it pretty much. If the Foveon sensor had been just mentioned in passing I could definitely understand leaving Fuji with a similar mention but generally Fuji and Sigma are considered in the same boat as doing something a bit different although arguably with the Nikon body and mount Fuji have had more success.
John
melgross - Tuesday, April 22, 2008 - link
I never saw an advantage to their designs. I can't see what purpose having a smaller photo site on the sensor would do. It just has more noise, and less dynamic range than the larger sensor. I've read their papers on the subject, and they don't seem to have made a good case for it. Somehow, I think they understand that now.Johnmcl7 - Thursday, April 24, 2008 - link
"I never saw an advantage to their designs. I can't see what purpose having a smaller photo site on the sensor would do. It just has more noise, and less dynamic range than the larger sensor. I've read their papers on the subject, and they don't seem to have made a good case for it. Somehow, I think they understand that now."Are you referring to Fuji? If so, your information is incorrect - the last measurement I saw put the S5's sensor at slightly more dynamic range than the 35mm sensor in the Nikon D3. Their real problem at the moment seems to be resolution as well as having the older D200 based body.
John
strikeback03 - Tuesday, April 22, 2008 - link
I think Sigma (and Foveon) would be better off if Sigma could license a major player's mount, like Kodak did with the SLR/n and SLR/c. There are plenty of people who would like to have the sensor for the situations where it excels, but have no interest in a whole Sigma SA mount setup.pinto4402 - Monday, April 21, 2008 - link
I've been reading Anandtech for over 8 years now. I was a bit skeptical about your doing articles on digital cameras; however, this article put my reservations to rest. Very nicely done.I see why it makes sense for Anandtech to write about digital cameras. The nexus between computer tech and camera tech are very obvious if you've been following the trends. I'm a professional portrait photographer. In the last few years, it has become virtually impossible to remain in business unless you have a firm grasp on the latest camera tech as well as computer tech. I spend as much time on my computer as I do behind the camera. The camera has become a computer accessory (or vice versa). Many old timers who are hanging on to film are slowly being forced out. I'm somewhat of an old timer myself because I learned about photography when it was cool to have a darkroom, but I embraced digital equipment early.
Your graphs make it very easy to explain to people why their P&S (piece of s***) cameras are simply not adequate for serious portraiture. The MP count is marketing crap. As you demonstrated, it's the physical size of the sensor that matters.
Looking forward to part II of the series. Also, do you have any solid info on the introduction of 5D Mk II?
bjacobson - Tuesday, April 22, 2008 - link
"The MP count is marketing crap."Mostly. If you're willing to do some post processing yourself, the higher MP will enable you to decrease the IQ gap between the higher end DSLR and the ho-hum consumer camera. For this reason, since I wanted something compact and didn't really need a lot of optical zoom, I chose the Canon SD1100IS. 8MP, and while you begin to get noise at ISO400, more at ISO800, and tons at ISO1600, using a non-linear digital filter should correct most of that without blurring the image much (if at all).
strikeback03 - Wednesday, April 23, 2008 - link
Problem is that the camera has already blurred away lots of your detail at ISO 400 and up.http://www.dpreview.com/reviews/canonsd1100is/page...">http://www.dpreview.com/reviews/canonsd1100is/page...
Too bad there is no option to reduce/turn off the in-camera NR, for those of us who own a better program for it already.
Wesley Fink - Monday, April 21, 2008 - link
I wish I did have definitive info about the 5D Mark II launch, but the best info I have is this fall at Photokina. Rumors pop up every month that the new 5D will be here in a few weeks - and the last rumor was a definite April 22, which is tomorrow. Rumors are just that - rumors.