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Sony HVR-A1 and HDR-HC Series
Sony's latest single-CMOS additions to their HDV camcorder line.


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Old February 14th, 2006, 12:13 PM   #1
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3 CMOS vs 1 CMOS

Hello all. I've been considering the A1U to augment my DVX for while and reading the posts in this forum. They have been very informative, and I appreciate the information. Just out of morbid curiousity, I have a question about the single CMOS ship in the HC1/A1U.

I have been reading a great number of reviews of these camera, I consistantly find the single CMOS rating close to (even better in some cases) to the 3 CCD imagers in the FX1/Z1U. I have seen a few that trashed the single CMOS - but I suspect they are from non-professionals who are operating off the old 3 is better than 1 theory when comparing CCDs. No reviews that actually did camera tests had a problem with it. Most reviewers seem to think this single CMOS provides slightly better latitude, color, and contrast.

I have a little B or more like a C camera. A Sony PC-1000 that I occasionally use as a crash/stick inside the bass drum/tape to the front of the motorcycle cam and it advertises it has 3 CMOS chips. Given, they are TINY, like 1/6 of an inch. BUT, the image quality is stellar when it is set up properly - no hype - just amazing.

Why would this camera have 3 CMOS and the HC1/A1U have 1 CMOS? Also, anyone with experience on the PC-1000, is the A1U menu and set up similiar? Thanks for any info.
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Old February 14th, 2006, 01:14 PM   #2
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Quote:
Originally Posted by Drew Buchanan
Why would this camera have 3 CMOS and the HC1/A1U have 1 CMOS?
I think that all other things being equal, single-chip cams are less-expensive to make, and they can be smaller and simpler too as only 1 chip to build in.
Sensors are expensive to make. I think that once Sony got their color filter system working well enough, it made sense for them to go single-chip for cams of this nature.
Having said that, i'm fairly sure that Sony have a 3CMOS chip HDV camera in the pipeline. It'll be more expensive, sure. Maybe the HC5? Just a guess.

Quote:
Originally Posted by Drew Buchanan
Also, anyone with experience on the PC-1000, is the A1U menu and set up similiar? Thanks for any info.
I'm not familiar with PC1000 menu, but every Sony cam i've played with the past year or so, the menu system seems remarkably similar in it's structure and functionality. So i'd guess that the A1 menu would be instantly familiar to you given you know the PC1000 menu well.
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Old February 14th, 2006, 03:23 PM   #3
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Yes, the PC1000 and A1 has a similar menu. The structure is exactly the same, but obviously, the A1 will have a ton more features. This menu has been around since the PC330 days (3 or so years ago) and hasn't been changed at all since then. Doesn't need to be, it's perfect as it is.

Regarding the 3 vs. 1 CMOS sensor, I agree with Stu. New 1-chip camcorders are closing in the performance gap with the 3-chip ones. The PC1000's 3 CMOS doens't compare with the A1's single one. Like Doughie said, advancement in technologies eliminate the need to spend more money on such things.

Last edited by Alexander Karol; February 14th, 2006 at 10:54 PM.
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Old February 14th, 2006, 03:34 PM   #4
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I think it's a size & resolution issue. You can fit three much smaller chips into a compact camera, but then to make them high enough resolution to produce decent HD images the sensors get pretty small and low light performance will drop (exacerbated by the splitting of the light to the three sensors).

Someone correct me if I've got this totally wrong, but I think the reason the HC1/A1 compare so favorably to the FX1/Z1 is because of the resolution of the CMOS chip. With a horizontal resolution of 1920 pixels you end up with 960 luminance samples and 480 each for the chrominance channels. The CCDs in the FX1/Z1 also have 960 horizontal pixels. So this means you're getting very similar sharpness/detail with little noticeable difference in the the color detail due to the 4:2:0 sampling of HDV.

The tradeoff is low light performance, because the pixels on the HC1/A1 CMOS are smaller than those on the equivalently-sized but lower resolution CCDs in the FX1/Z1. In bright sunlight the difference between the cameras isn't significant, but in low light the HC1/A1 is barely adequate - a lot of detail and resolution is lost to noise.

Now imagine they'd put three smaller chips into the HC1/A1 like they did with the PC100, but they were higher resolution in order to produce a suitable HD image. The barely useable low light performance of the HC1/A1 would be significantly worse, and the improvement in color rendition would be negligible. To do three CMOS with the current chip would probably push the price into the same range as the FX1/Z1, as well as possibly increasing the size/weight (which I consider one of the biggest strengths of this camera). So the single, large, hi-res CMOS is the best compromise between cost, resolution, size, and low-light performance.

All that aside, it's a great camera and I know you won't be disappointed if you compare the footage side by side with the PC100.
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Old February 16th, 2006, 06:45 AM   #5
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I have always wondered why the current digital stills cameras don't use three ccd's - they all seem to be able to reproduce the full colour spectrum from the output of just one single hi-res (in most cases far higher than video) chip...
It doesn't make much sense to me why video needs three chips for the best performance, wheras stills photography doesn't although I admit this seems to be the case (until very recently by what I read here) - my trusty 3yr old 3 chip MX300 is still hard to beat from a colour saturation/fidelity POV.
This little Sony cam looks absolutely amazing though... :-)
(edit - I see that the forum still regards me as a 'regular' even though I haven't been around here for over two years... :-)
The HC1 has rekindled my enthusiasm for home video! :-)
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Old February 16th, 2006, 09:54 AM   #6
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Video and stills use completely difference processing methods. Thinks about it; it requires far less processing power to capture one frame than 60 frames per second. Therefore, something needs to be sacrificed. The single frames that digital cameras capture, are most of the time well-lit due to the flash; unlike video. This also requires more processing. Nowadays, technology is really reducing the necessity for 3-chip camcorders. There are plenty of 1-chippers out there that can out-perform 3-chip camcorders. Look at the HC1 for example, you can capture pretty decent stills from the video it produces.
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