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Contax ND

Dirk,

Sure I can give it to you. We just need to change it a bit so the magazine does not start dripping with venom that you have exactly the same thing.
 
(from previous message) "John, I would not be surprised because D1s employs CMOS chip, which is inherently less charp than CCD."

I'd be interested in what some of you think of an article at digitimes.com about Micron developing a CMOS chip that is allegedly sharper than CCDs. I don't know much about this technology; for those who know, please drop a quick message. (I actually followed a link from www.tomshardware.com to the digitimes article)
 
> (from previous message) "John, I would not be surprised because D1s > employs CMOS chip, which is inherently less charp than CCD."

That's not true (I assume you mean Sharp). Where did you get that information?

The technology of the image sensor has not much at all to do with how "sharp" the image is that comes out of the sensor, except for saturation and bloom, which will not occur in normal use, and should be mitigated by design. Sharpness is based on resolution, as in number of pixels and magnification, and optics. Any image can be post-processed to make it sharp. Even those from a Holga!

Austin
 
>The technology of the sensor determines the resolution and the quality of the image. This is why the Foveon detector is superior. > William
 
> >The technology of the sensor determines the resolution and the > quality of the image. This is why the Foveon detector is superior. > > William

William,

The technology of the sensor DOES NOT determine the resolution of the sensor. The resolution of the sensor is determined by the number of photosites, period. The Foveon happens to use three sensing elements PER photosite, but that does not have a thing to do with spatial resolution, it has ONLY to do with tonal resolution (more bits/photosite). Whether the sensor gives 3M pixels from a Bayer pattern, or 3M from a Foveon, they both have the same RAW resolution, 3M photosites.

It is also NOT a given that the Foveon is "superior", as it depends on what you mean by "superior". The images from a 3M Foveon sensor are marginally "better" in some aspects than a 3M Bayer pattern image sensor, but they are also "worse" in some aspects.

Also, comparing digital images and claiming one sensor is better/worse than another is somewhat of an exercise in futility, unfortunately. You need to compare RAW image files, which most people can't do. The reason for this, is processing the image (which happens in most cameras unbeknownst to you, and unstated by the manufacturer) removes the subjectivity from the imaging sensor to the processing. At the very least, you need to know ALL the processing that has happened to the raw image between the sensor and your seeing it. What you are comparing is TWO CAMERAS, NOT TWO SENSOR TECHNOLOGIES. That is an entirely different problem.

Austin
 
>Austin, are you saying that whether the technology allows 100,000 pixels or 10,000,000 pixels has no effect on the resolution? > William
 
> >Austin, are you saying that whether the technology allows 100,000 > pixels or 10,000,000 pixels has no effect on the resolution? > William

William,

There is nothing about the Foveon vs CCD vs CMOS that "allows" the number of photosites (NOT pixels, pixels, as we use them, are something different).

You can pretty much make the size of the cells to be anything the "process" (meaning the silicon fabrication process) allows, but the smaller the photosites, the higher the noise. In the type of imaging sensors used in the mid to high end DSLRs, the noise is the limiting factor to cell size used. You aren't going to sell a high end DSLR that has bad noise properties. You can make an array as large as you want, to the size of a wafer...but you won't get very good yield, as a good number the photosites will not be operational.

Again, the spatial resolution is determined by number of photosites, period, whether the photosite has one sensing element or three vertically stacked. The Foveon "technology" does not necessarily allow you to have more photosites than other "technologies" in either the same unit area, or in overall area. In fact, it's probably less. The number of photosites is limited by the cell size, and the cell size is typically limited by noise.

Consumer digicams and digital video cameras use what is called "interline" sensors. They can use cell sizes down to 3u...but...they are very high noise, which is one of the major easons why they are not used in anything that requires image fidelity, like DSLRs. Consumer digicams and video tolerate noise. Typically, 6u is the smallest cell that you can currently use for decent noise characteristics, and more like 9u+. But, this really doesn't have much to do with whether it's a Foveon, CMOS or CCD...

Austin
 
> Theoretically, the number of "sensors" and the degree of miniaturization is limited by the wavelength of light, not just the technology- that is, you can only have "sensor" size/density improved until they approach the 400-800 nm range. I'm not sure we would need it anyway but this goes to show that digital cameras with a gzillion pixels are not to be expected, even in the distant future.

Regards

Andrei
 
> > Theoretically, the number of "sensors" and the degree of > miniaturization is limited by the wavelength of light, not just the > technology- that is, you can only have "sensor" size/density improved > until they approach the 400-800 nm range. I'm not sure we would need > it anyway but this goes to show that digital cameras with a gzillion > pixels are not to be expected, even in the distant future. > > Regards > > Andrei

Agreed, but that isn't the limiting factor with current sensors. You also need just so many photons to "register", therefore there is a minimum size of detection area as well. I do believe that minimum size is way above any limitations that wavelength imposes at this point in time.

Regards,

Austin
 
>Austin, >

You say " The Foveon 'technology' does not necessarily allow you to have more photosites than other "technologies" in either the same unit area, or in overall area. In fact, it's probably less. The number of photosites is limited by the cell size, and the cell size is typically limited by noise."

This is self contradicory. If as you say, the cell size is limited by noise - which I can accept - then the more information gathering you can pack into a single photo site the better off you are. If it takes three "normal" photo sites to produce one pixel, and if you can produce one pixel with one photo site the area required is cut by approximately a factor of three. In the case of the detector used in the Sigma SD9, there are 3,429,216 photosites (2268 x 1512), hence pixels, in an area of 20.7 x 13.8 mm (0.0091269841 mm on a side per photo site) To achieve this same density of photo sites using the old single layer technology, and three photo sites per pixel, would require a photo site size considerably less than 9 microns which would increase noise dramatically.
 
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