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Old Aug 6, 2007, 10:21 AM   #1
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I'm hoping some one can clarify some points for me on cmos and ccd as far as which is better for light gathering there by making them better for low light.

In the past we all assumed CCD was better, and considered CMOS to be more on the line of for toys. That is until Canon released it's amazing DSLR D60! That changed the way we looked at CMOS! Even I being a long time Nikon man bought the D60 and had to admit the quality was excellent, more film like!

Then we started reading that CMOS was actually better for gathering light!

Now I'm reading the opposite again about these hybrids, so I am once again lost.

Is it the physical size of the cmos and ccd used in these hybrids that really make the difference more so then the chip? The physical size would effect the physical size of each pixel. I know that the larger the pixel size is more important for light gathering then the pixel count. My D1H was better then my D1X for low light!

Any input on this subject would be appreciated! I'm sure I can't be alone on this.

Thanks!
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Old Aug 6, 2007, 1:53 PM   #2
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Well, there are several things to keep in mind. CMOS and CCD imagers work in different ways. a CMOS image can be as good as a CCD, I think, but usually they are not. Most of your toy devices use CMOS sensors because they are cheaper to impliment, and less power-hungry. But they also tend to use very small CMOS imagers, which don't capture light well. My Aiptek IS-DV2 takes photos extreemly well outdoors. You would not be able to look at the image and say whether it was a CCD or CMOS imager. But it is a small sensor so it collects less light than a more expensive camera would use.

The Sanyo cameras do something very impressive. Normally if you have a megapixel CCD but you are recording video at 640x480, then the camera will essentially skip several pixels in between each pixel that is used to make the 640x480 image. It requires too much CPU power to take the whole CCD and interpolate it down to 640x480. So even if the sensor is very large, the more pixels it has, the worse light performance it will have. The Sanyo cameras are one of the first that actually really do use the whole CCD. It actually takes a large megapixel image and resamples it down to 640x480 for each frame of your video. So this allows it to collect light even better, while cancelling out any static you might get otherwise.

Sometimes it is difficult to tell from specifications exactly what kind of picture to expect, but here is the best info I can give you:
  1. the size of the imager.[/*]
    • 1/8" VERY BAD[/*]
    • 1/6" BAD[/*]
    • 1/4" Getting better[/*]
    • 1/3" lots better[/*]
    • 1/2" the best!!!
    [/*]
  2. The design of the apperature, iris, and shutter.[/*]
  3. The manner in which the camera uses the pixels
[/*]
These things are probably the most important considerations for low-light performance. Whether it is a CMOS imager or a CCD probably isn't as important. I think that in the next few years CMOS images will become more mainstream on high-end products. Right now they have a bad name because people associate them with toys. Once more good products come out with large CMOS imagers, I think they will start to cut into the market more.
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Old Aug 6, 2007, 2:00 PM   #3
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Just look at it this way

you want a Plazma and know how it works that is CCD

you want a lcd and know how it works that is Cmos

rather explain, what is on the net? the CCd lens cost a lot mre , and the cmos less expensive?

I love the hybrids I have with Cmos, the Go I am now leaning back into with a cmos , over the casio Ex-v7 with ccd? the casio showssmear like a star trek , beam me up effect? 2nd ccd hybrid that did this to me? my JVC well no words love it.
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Old Aug 7, 2007, 11:22 AM   #4
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adric22 wrote:
Quote:
Well, there are several things to keep in mind. CMOS and CCD imagers work in different ways. a CMOS image can be as good as a CCD, I think, but usually they are not. Most of your toy devices use CMOS sensors because they are cheaper to impliment, and less power-hungry. But they also tend to use very small CMOS imagers, which don't capture light well. My Aiptek IS-DV2 takes photos extreemly well outdoors. You would not be able to look at the image and say whether it was a CCD or CMOS imager. But it is a small sensor so it collects less light than a more expensive camera would use.

The Sanyo cameras do something very impressive. Normally if you have a megapixel CCD but you are recording video at 640x480, then the camera will essentially skip several pixels in between each pixel that is used to make the 640x480 image. It requires too much CPU power to take the whole CCD and interpolate it down to 640x480. So even if the sensor is very large, the more pixels it has, the worse light performance it will have. The Sanyo cameras are one of the first that actually really do use the whole CCD. It actually takes a large megapixel image and resamples it down to 640x480 for each frame of your video. So this allows it to collect light even better, while cancelling out any static you might get otherwise.

Sometimes it is difficult to tell from specifications exactly what kind of picture to expect, but here is the best info I can give you:
  1. the size of the imager.[/*]
    • 1/8" VERY BAD[/*]
    • 1/6" BAD[/*]
    • 1/4" Getting better[/*]
    • 1/3" lots better[/*]
    • 1/2" the best!!![/*]
  2. The design of the apperature, iris, and shutter.[/*]
  3. The manner in which the camera uses the pixels[/*]
These things are probably the most important considerations for low-light performance. Whether it is a CMOS imager or a CCD probably isn't as important. I think that in the next few years CMOS images will become more mainstream on high-end products. Right now they have a bad name because people associate them with toys. Once more good products come out with large CMOS imagers, I think they will start to cut into the market more.
Well with the design and size limitations of these hybrids, I think we are stuck with the smaller imagers. I would love to know what the sizes are on current models, my guess is 1/8 and/or 1/6. This is the kind of information consumers really need to know instead of the fluff and gimmicks. Most really push the envelope on false advertising, or at the very least, being misleading!

My experiences with miniDV and consumer digitals up to pro DSLR's, is the actual size of the imager is just as important if not more important then the actual pixel count.

For example, a 1/4" 6MP CCD and a 1/4" 7MP CCD.

all the tests I have seen shows that the 1/4-6MP will be better in low light then the 1/4-7MP. And a 1/4" 4MP will be even better in low light.

The reason of course is because the actual individual pixels will be larger and become more sensitive to light.

The problem has been, at least on the consumer level, by cramming more picels on a small chip the pixels become smaller, and do not perform as well in low light. I realize we have come a long way to compensate for this but it is a up hill battle.

My interest in CMOS is because if it actually costs less then CCD's, and functions differently, why not do more R&D with them. It may be possible to produce a 1/8" 8MP cmos with the same light sensitivity as a 1/3" 4MP, but still produce the resolution and sharpeness of a 8MP ccd!

There must be a reason Canon does not use a cmos for their pro line, despite the fantastic results their D30 and D60 provided. But for these hybrids it may still be a workable solution.

I just didn't know if there were some other charactoristics that would make a cmos perform better. I understood the basic theory, but was confused on some conflicting reports I read.

But these hybrids are so small, and thats what I like about them too, we need some break thru technology to really dramatically improve their quality with a smaller imager, or else they will have to get a little larger to accomodate a larger imager.

I'd like to see them stay small.

Thx for the input!!
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Old Aug 7, 2007, 12:14 PM   #5
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Quote:
all the tests I have seen shows that the 1/4-6MP will be better in low light then the 1/4-7MP. And a 1/4" 4MP will be even better in low light.
You are right, but the main problem that haunts us is the stupidity of the average consumer. The manufacturs know that it sounds better to advertise a high megapixel rating than it does to advertise good low-light performance. So they keep pushing for the higher pixel count, despite the obvious problems in low light. In the consumer line of camcorders it hasn't been as much of an issue because everyone expects a camcorder to be television resolution and so the only thing to worry about is the size of the CCD. But these hybrids are trying to sell people on megapixels (why else do they lie about the resolution with their interpolated specifications?)

From my perspective, take the Aiptek IS-DV2 (or just about any of their products) I would probably have been more satisfied with the unit if it had the same sized imager but only 640x480 pixels. It is likely that the indoor video recording would be very much improved, at the loss of being able to take multi-megapixel still images.

Something occurred to me the other day about Aiptek, though. They appearently realize that they have a very high return rate on their products. more than likely most of those returns aren't defective, simply didn't live up to expectations. Since their products are sold in plastic blister-packs, the stores will always return them to manufacturer rather than re-sell them again on the shelf. If you look at their website, you'll notice they have an endless supply of refurbished models that they sell there. Those are all very likely the ones that were returned from places like Target.
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