8 MegaPixel Digital Sensor Unveiled

hdtv writes "Micron has unveiled an 8-megapixel digital sensor, that 'enables pocket-sized cameras and cell phones to capture bursts of 10 high-quality photos in a single second or even high-definition video.'" From the article: "'We're saying it can go in a point-and-shoot camera selling in the $200 to $300 range,' said Suresh Venkatrama, Micron's director of the digital camera segment. 'It brings high-quality digital video and photography down to the consumer space.' The new sensor is a type of chip known as a 'complementary metal-oxide semiconductor,' or CMOS. Analysts say the technology, which is also used in memory chips and microprocessors, will challenge the dominance of traditional light-sensing charge-coupled devices, or CCDs."

Comments

Sensors? Pfft...

[Locus Mote]

In terms of high-end photography, there are several requirements which rate MUCH higher than simple FPS:

Input Dynamic Range. This is the range of light values in a scene which the sensor "sees" and is able to record. In order to understand this, think of light at dusk reflecting off wet pavement in the distance. The super bright orange glare hitting your eyes is extremely high intensity light, while the shadowed sides of houses and trees and things are low intensity light. Both of these elements have detail that can be recorded. With a low dynamic range, one or the other can be exposed properly. With a high dynamic range it is possible to capture the detail in very dark shadows and very bright highlights without clipping. (Clipping is truncation to flat black or white pixels with no detail). Chemical film, especially positive film (slide film), has a dynamic range which obliterates the best digital sensors.

Falloff. This is the ability to clip gracefully. When using any type of transducer, whether it's a microphone, a square of film or a digital sensor, there is a response curve which maps values input values (light/sound) into recordable output values. In the age of analog (vacuum tubes, vinyl records and chemical film) the response curves were all based on Calculus. They literally rolled off (logarithmic) at the ends. This meant that as the microphone, vacuum tube or film overloaded, it did so gracefully with a smooth transition to clipping. In the digital world, our chips are "dumb". They can only do algebra, not calculus. Their falloff is linear. 8-bit = 256 values, 16-bit = 65536 values, etc. Anything above or below this is immediately clipped to white or black, on or off. The digital world is flat, if your input source is flat, you sail right off the edge into infinity.

Single Pixel Resolution. 99.99% of digital camera sensors use a single layer of matrixed sensors (Bayer array). These sensors are located in gangs of three, similarly to the pixels on an old CRT television. The problem is that each sensor can only see red, green or blue. There is a lot of jibber-jabber that I could go on with, but essentially, bayer sensors really only see 1/3 of the picture information their lenses dump on them. Chemical film is stacked in layers, thus each pixel location "sees" all three RGB. Currently only the Foveon X3 sensor in Sigma digital cameras is capable resolving all the information in each color channel at each individual pixel location.

Now, even if this new Matrix chip performs at even the sub-par level of today's CCD camera sensors, simply buying a camera with one in it does not by any means guarantee quality photography. Back when the sensor (film!) was interchangable from camera to camera, there was still intense competition between camera and lens manufacturers. This is because the sensor can only "see" the image that the lens and camera body deliver to it. The most important factor is the lens! Imagine rubbing vaseline on your glasses and walking around like that all day. This is life with a cheap camera lens. There's a reason why most professional lenses, without a camera body, cost betweed two and ten times as much as an entire point and shoot camera. If a lens is a valve for light, then a professional lens is like a firehose, a prosumer is like a garden hose, a point and shoot is a drinking straw and a cameraphone is a hypodermic needle.

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That's my 2(6.022*10^23) cents worth.

Re:Where's the useful cut-off point?

[swillden]

However, I've also got an 8 mega pixel Canon digital SLR, and the picture quality is vastly superior

What lens do you have on that? I just bought a Rebel XT and although I was really impressed with the quality of the images, it was pointed out to me that the 18-55mm f/3.5-5.6 lens it came with really isn't a very good lens. It's not very sharp, especially in the corners, it's a slow lens, doesn't have very good depth of field, etc. At a friend's suggestion, I bought an inexpensive 50mm f/1.8 prime (non-zoom) lens, and I have been amazed by how much better the image quality is. I've shot the same scene with both lenses and the difference isn't subtle at all. Not only is the 50mm much sharper, but when you look at the pictures side by side, it's obvious that the 18-55mm gathers light unevenly. The picture is darker in all of the corners and in the right and left edges. Pictures with high contrast edges show pretty obvious color distortion with the 18-55 as well.

Oh, and if you're taking pictures indoors, that f/5.6 is just way too slow. You need a lot of light with that lens.

Note that I'm not actually knocking the 18-55; compared to my old camera (which wasn't junk, either) it takes *fantastic* pictures. But experimenting with the 50/1.8 has made me realize that the optics matter -- a lot. That seems like kind of a stupid thing to say, in retrospect, since it should be utterly obvious that optics are important to a camera, but I kind of assumed that the differences between lenses, other than zoom power, were subtle and maybe even subjective. They're not. Which makes it obvious that the tiny lenses that can be crammed into a compact camera are always going to be limited. No matter how many megapixels the sensor can capture, if the glass can't focus the light onto it properly, the pictures aren't going to be very good.