1 or 3 ccd ???

[Fredrik Tarnell]

I'm having trouble understanding WHY I need a 3 ccd camera. Dont get me wrong I previously owned a Canon XM2 and it was great!!

But... A digital SLR (still) cameras use the 1 ccd concept and they dont get trouble with bad color reproduction......

OK. a still camera doesn't have to expose 25(pal) images per sencond but still....

If I'm shooting windsurfing ONLY... Meaining always in good lightning condition... Will I be better of with a larger (ref. to the ccd) 1 ccd camera ??? I need shallow DOF for interviews and such....

Soo... Is it the light issue causing the colors to go bad on a 1 ccd or will i get bad colors in general???

[Chris Hurd]

Hi Fredrik,

A CCD is a monochromatic device. It doesn't know what color is. There are a couple of methods used to force a color-blind CCD to accurately indicate color information. In a 3-CCD camcorder, light from the lens enters a prism and is split into the primary color wavelengths of red, green and blue. One primary color per CCD sensor. The camcorder's processor puts it all together again. So that's one method.

In a 1-CCD camcorder and in digital still cameras (which as you know also contain a single CCD or CMOS imaging sensor), there's a color filter mask built directly onto the face of the chip. This color filter overlay provides a way for each pixel on the sensor to indicate a particular color wavelength.

Most digital still cameras these days -- the better ones, anyway -- have an RGB color filter. This actually emulates the 3-CCD look because it builds color infomation from the primary color wavelengths of red, green and blue. Digicams which are equpped with RGB color filters are becoming more common all the time. For instance all Canon PowerShot digicams and Digital SLR cameras have RGB color filters, and that's why images taken by these cameras have such vibrant and accurate colors.

Video camcorders on the other hand are most often equipped with a CMY or complementary color filter mask on the face of their single CCD image sensors. A CMY or complementary color filter separates incoming light from the lens into cyan, magenta and yellow color wavelengths (these complementary colors are the exact opposites of the primary colors red, green and blue). A common 1-CCD camcorder equipped with a complementary color filter produces adequate color. There's nothing bad about it at all. In fact it produces readily acceptable color, and the only real way to notice any difference is to compare it with a 3-CCD camcorder... then you'll easily see the difference in color accuracy. The advantage of a CMY or complementary color filter is that it typically produces a cleaner signal with less noise and better lowlight performance than an RGB color filter. Unfortunately in the world of consumer electronics, the marketplace tends to put a somewhat misguided emphasis on lowlight performance over color accuracy. If you ask me it should be the other way around.

However there are a handful of 1-CCD consumer video camcorders which have RGB color filters and these little gems really do produce the color accuracy of 3-CCD camcorders. I'm not familiar with all RGB-equipped 1-CCD camcorders, but I can tell you that the higher-end Sonys and the Canon Optura series have them. They are typically more expensive than your basic single-chip camcorder but they're well worth the extra money. The inherent disadvantages of using an RGB color filter on a video camcorder are counter-balanced by a better-than-normal DSP, or Digital Signal Processor. The Canon Optura series for instance uses a version of Canon's proprietary Digic digicam DSP (it's called Digic DV in the Optura). Check out our Optura camcorder forum and you'll find Optura owners talking about how the new Op 60 model meets or exceeds the 3-chip GL2 in terms of color accuracy and sharpness. That's due entirely to the Optura's RGB color filter and Digic DV processor.

Hope this helps,

[Jeff Wilson]

I just read this article in TVTechnology. I thought it was a good read.

http://www.tvtechnology.com/features...04.06.05.shtml

Basicaly both the one chip and the three chip concept have their problems. In the end it's all about trade offs.

[Nick Jushchyshyn]

Another factor to consider is that the camera companies tend to not use the same optics in their 3CCD cameras as their single CCD models. Since customers are willing to pay a premium, the 3CCD cameras tend to have better lensing than the less expensive single CCD units. Even before the image hits one or more CCDs, this factor alone dramatically effects your image quality.

The optics used in Canon's 3CCD cams are much different than thier single CCD cameras, for example, so when you compare, it's not just 1CCD vs 3CCDs. Instead, you could be comparing "this 1CCD unit with a plastic lens" to "this 3CCD cam with an optically stabilized, fluorite lens system".

[Chris Hurd]

Nick I'm with you all the way except for one thing... there are no plastic lenses in consumer camcorders. I wish I could find the joker who originally perpetuated that myth a number of years ago on usenet. There are a number of optical elements that make up a zoom lens in a consumer DV camcorder, one or two of which might be made of a glass-like composite material, but the front objective is always glass. Maybe it's not the best glass in the world, but it is glass... and scratches, cracks and shatters just like you'd expect a glass lens would. And the occasional composite element within is much more like glass than it is like plastic.

[Jeff Wilson]

Just out of curiosity, are there any three chip still cameras out there? Professional, Still digital photography seems to have fixed on the SLR design.

[Nick Jushchyshyn]

Originally Posted by Chris Hurd

Nick I'm with you all the way except for one thing... there are no plastic lenses in consumer camcorders.

Sorry. Hyperboli on my part.

rephrase to ....

comparing "this 1CCD unit with an economy quartz lens" to "this 3CCD cam with an optically stabilized, fluorite lens system".

:)

[Nick Jushchyshyn]

Originally Posted by Jeff Wilson

Just out of curiosity, are there any three chip still cameras out there? Professional, Still digital photography seems to have fixed on the SLR design.

There's an expensive cheat out there by Foveon.
Check it out here.

[Jeff Wilson]

Yeah, I have seen that one. It is very interesting, it could be the future of both still and video, though with Philips liquid lenses and all the other research going on with camera phones, it is hard to imagine what cameras will look like in the next decade.

[Fredrik Tarnell]

OK... thanks for all the answers!

I think the answer about the "not sooo good optics" in cheeper cameras made the most sense...

I did understand the part about different filters but still not WHY the still have good enough color accuracy..... and WHY there are no 3-ccd still cameras...

If the optics where better and the DSP was better.... Are we talking about the new Sony HVR-A1 as such a camera????

1ccd (or CMOS...) ...good glass and good processing??? Maybe we'll just have to wait and see???

[Chris Hurd]

Originally Posted by Fredrik Tarnell

WHY the still have good enough color accuracy... and WHY there are no 3-ccd still cameras?

Sorry, I thought I had made that clear... most all digital still cameras are using RGB color filters. An RGB color filter combined with a very good DSP equals the same color accuracy as a 3-CCD camera. Plus it's a lot smaller, and everybody wants a smaller digicam these days.

If the optics where better and the DSP was better... Are we talking about the new Sony HVR-A1 as such a camera?

Yes, we are! I think it's going to be nothing short of amazing. I also predict that 3-CCD arrangements will be going away eventually. In fact that's already starting to happen.

[Fredrik Tarnell]

Originally Posted by Chris Hurd

Sorry, I thought I had made that clear... most all digital still cameras are using RGB color filters. An RGB color filter combined with a very good DSP equals the same color accuracy as a 3-CCD camera. Plus it's a lot smaller, and everybody wants a smaller digicam these days.

OK Thanks!

[Laurence Currie-Clark]

Originally Posted by Chris Hurd

Hi Fredrik,

In a 3-CCD camcorder, light from the lens enters a prism and is split into the primary color wavelengths of red, green and blue. One primary color per CCD sensor. The camcorder's processor puts it all together again. So that's one method.

The role of the prism is to actually split the image into three exact copies directioned towards the CCDs. In between each CCD and the prism is either a R, G or B filter. In this manner each CCD gets the whole color bandwith.

[Jeff Wilson]

I believe on a lot of the newer designs the mirror itself acts as a filter by only reflecting red, blue or green light. Everything nowadays seems to be about being able to shoot in as low as light as possible. I think the prism has been modified so that it doesn't have to contend with a filter factor. I might be wrong, but it is something I remember reading a long time ago.

[Chris Hurd]

Well, my own explanation was over-simplistic on purpose.