HPX500 vs. HDX900

S

skillimon

New member
Trying to sort out a new camera purchase.
Setting aside all the issues related to P2 vs. tape, how do these two cameras stack up,camera to camera? Picture quality, low-light capability, easy of use. Any experiences or comments helpful.
 
bump.

Anyone with info on this? I think I've done a fairly thorough job searching the board for such info; and the Panasonic site is TRAGICALLY uninformative. They make very little effort to differentiate their product lines and explain the differences. A bunch of comparisons were made with the 2000, but not with the 500 vs. 900.... so what are the differences, besides tape?

-Kevin
 
As far as I know, the HDX900 does not do variable framerates but it does have an HD sensor whereas the HPX500 uses an SD sensor like the HVX and achieves HD resolution through pixel shifting.


Marco
 
marco0782 said:
As far as I know, the HDX900 does not do variable framerates but it does have an HD sensor whereas the HPX500 uses an SD sensor like the HVX and achieves HD resolution through pixel shifting.


Marco
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The hvx is not an SD sensor - pixel shift doesnt make resolution from nothing - its a smart way of having less noise and more resolution.
 
The hvx is not an SD sensor - pixel shift doesnt make resolution from nothing - its a smart way of having less noise and more resolution.
Click to expand...

Yes it is an SD sensor. An HD sensor is slightly above 2 megapixels whereas the HVX sensor is around 0.6 megapixels.

Pixel shift is a smart way of achieving HD-like results with a sensor that has less pixels. I don't see that noise has anything to do with it because the HVX is slower and noisier than the Canon HV20 with its full 1920x1080 sensor.

Pixel shift works pretty well but it's no substitute for the real thing. The image from an HV20 is sharper, in my opinion, but my HVX holds up very well against the XLH1.


Marco
 
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The HVX200 and the HPX500 both have HD sensor blocks, no question about it.

Pixel shift simply combines 3 sensors into one higher resolution one.


- Mikko
 
From DVinfo.net:

"It's worth noting that this resolution increase applies mainly to luminance, and is most effective for a subject with low colour saturation. For a highly saturated subject, pure red lit, say, all the output will be from the red sensors, none from the green or blue, so the pixel shift technology can't have any effect.

Since the human eye is more sensitive to luminance resolution than chrominance, and most TV systems have more limited chrominance resolution anyway, it should generally be seen as a good thing."
 
marco0782 said:
Yes it is an SD sensor. An HD sensor is slightly above 2 megapixels whereas the HVX sensor is around 0.6 megapixels.

Pixel shift is a smart way of achieving HD-like results with a sensor that has less pixels. I don't see that noise has anything to do with it because the HVX is slower and noisier than the Canon HV20 with its full 1920x1080 sensor.

Pixel shift works pretty well but it's no substitute for the real thing. The image from an HV20 is sharper, in my opinion, but my HVX holds up very well against the XLH1.


Marco
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I could cite sources of why it is an HD chip - or I could post a resolution chart and show that it indeed shoots HD images - which would be impossible with an SD chip - but this question has been done and redone - just do a search here.
 
"And that varies from a single HD chip how exactly?"

In that it only produces HD resolution for luminance. If you are seeing an all red image it will be in SD. With a 3-chip HD sensor there would be 1920x1080 red pixels.
 
aah.. a 3 HD-sensor design, sure, but in a camera this size, the pixels on the sensors would be tiny, and dynamic range would suck. That's why the only cameras with 3 fully HD chips are 2/3" cameras, where the size increase allows for bigger pixels.


I was asking how pixel shifted HD CCD blocks differ from a single HD chips though - as in, what make the HV20 with 1 CMOS chip any higher rsolution than the HVX with a pixel shifted CCD block for HD?

- Mikko
 
marco0782 said:
Yes it is an SD sensor. An HD sensor is slightly above 2 megapixels whereas the HVX sensor is around 0.6 megapixels.
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There's nothing about this statement that's correct though. It shows a fundamental misunderstanding of how sensors are read and interpreted. You do not ever read one chip -- individual pixel counts on a single chip are largely irrelevant. It's the total combination of all the chips being read together that produces the final image. And in that context, the HVX resolves a 2K image; the imaging block is a 2K imaging block (regardless of how many pixels are on each individual chip).

I don't see that noise has anything to do with it because the HVX is slower and noisier than the Canon HV20 with its full 1920x1080 sensor.
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Marco, come on. This statement is so incredibly easy to disprove, why do you even say things like this? The HV20 is an ISO of 80. The HVX is an ISO of 320. The HVX is two full stops faster than the HV20. To make an HV20 "faster" than an HVX you'd have to pile in 18dB of gain, and at that point it's far noisier than the HVX.

Any perception of the HV20 being "faster" is probably driven by the fact that it uses such a prodigious amount of electronic gain, up to at least 27dB...
 
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The HV20 is an ISO of 80. The HVX is an ISO of 320.
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My mistake, it is the XH-A1 that is faster and less noisy even though it has more pixels on its sensors.

It's the total combination of all the chips being read together that produces the final image.
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I'm eager to know how the green and blue sensors contribute any data besides luminance when recording a red object.
 
what else is there to contribute from the green and blue except luminance no matter what the size of the 3 ccds - it wouldnt matter the resolution - the offset is still there for the luminance
 
Well, ALL sersors only detect intensity (luminance). The Prism is simply a color filter to direct the light to the correct sensors.

Compare to how a single chip camera works, using a bayer filter:
3shotcm_figure1.jpg

The reported resolution of the chip itself is full HD, but each color gets way less resolution!
Those colors are of course then processed into the component video signal.
Those 3 color "layers" match the 3 CCDs of a 3CCD camera, of course there arn't wasted pixels for each color, but simply larger (more sensetive) pixels that are positioned (using "pixel shift") in the right spots to provide the colors, but still the combined overall luma grid.

This is why ALL the 1/3" 3CCD cameras use pixel shift, it just makes sence.



Of course when all this becomes a component video then it's all "brightness of each color" signals for RGB processing & compression .. so if you only get one color into the camera, then you'll only get one color thorugh the compression anyway, so what loose light sensitivity over it?

- Mikko
 
Thanks for clarifying, that makes sense.

But if you are recording a deeply saturated red object, how do you get 1920x1080 resolution if two of three sensors are not receiving any light at all? You don't. And so in practical terms unless all three chips are being used to their fullest you are not getting true 1920x1080 resolution.
 
True enough. But it would be pointless to capture more than can be recorded by the recording codec.

A 4:2:2 codec (Like DVCPRO-HD) will only record every other color sample anyway.
And a 4:1:1 or 4:2:0 codec (Like HDV) will only record every 4th color sample.

So even if you could capture a full 1920x1080 red signal, the codec wouldn't be able to store all those pixels anyway.

- Mikko
 
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