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JVC GY-HM 600/700/800 Series Camera Systems
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Old April 15th, 2009, 02:25 AM   #16
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Originally Posted by Steven Lyons View Post
I just don't get it, my 101 is virtually noiseless, what happened, did the 101 have sony ccd technology and sony got pissed that jvc might get too successful and left jvc to use their own technology which resulted in the 200 series?.
I think I can set you mind at ease. The 100 series uses two 640x720 sensors mounted together so each sensor only had to run at half the data rate as would a single 1280x720 sensor. Less speed = less power = less heat = lower noise BUT, getting both halves to match = not EZ.

I believe the 200 switched to a 1280x720 sensor which eliminated the matching worries, but reversed the equation: 2X faster = more power = more heat = more noise.

Nothing to do with JVC vs Sony.

There is a way to avoid the noise problem. Move to a 1/2-inch sensor because the package surface area provides greater heat dissipation and -- in theory -- less noise. Or, switch to CMOS which uses far less power so less heat so less noise. Although, CMOS has it's own inherent noise problems that EXMOR tek tries to fix.

The only generalization is that when it comes to CCDs -- bigger is better. But, for the last decade all companies have been pushing for greater profits by using very tiny sensors which given an 8" or 10"or 12" production disc makes each chip really really cheap. I'd love to know the cost difference between 1/3" and 1/2". Is is dime? A dollar? Would a 1/2" 3CCD optical block with CCDS cost more than $5 more than a 1/3". Everything camerawise else is the same. I'm wondering why anyone builds a "pro" camera with less than 1/2" CCDs and why any "prosumer" camera has less than 1/3" CCDs. The smaller chips FORCE so many compromises in design that need not be.

There is a reason why pro SD camcorders had 2/3" CCDs. With HD, it seems odd that buyers now accept that 2X or 4X more pixels can be put on a 1/3" chip. And, the use of i/5th and 1/6th inch chips forces one to believe in magic. :)
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Old April 15th, 2009, 03:19 AM   #17
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But isnt the pixel size another important factor? Not so much with noise but with sharpness @ small iris? I have the HVX 201 and the HV20 and am just editing footage shot with both.
It mixes well! the HV20/ HV30 are truly incredible!!!
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Old April 15th, 2009, 04:54 AM   #18
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Originally Posted by Steve Mullen View Post
I think I can set you mind at ease. The 100 series uses two 640x720 sensors mounted together so each sensor only had to run at half the data rate as would a single 1280x720 sensor. Less speed = less power = less heat = lower noise BUT, getting both halves to match = not EZ.

I believe the 200 switched to a 1280x720 sensor which eliminated the matching worries, but reversed the equation: 2X faster = more power = more heat = more noise.

Nothing to do with JVC vs Sony.
Steve, well I don't know if you really believed you would put my mind at ease.. but you have, although I thought JVC, in early propoganda promoted the 101e as true 1280x720
sensors.
it was important to me to try and make sense of what appears to be a decline in image quality from hd 100 to hd 200 series cameras and appears to continue through to the HM series, I mean I could dial in + 6db on the 101e and hardly notice any difference in noise.

Anyway thanks again steve, you have given me a stable platform to work from.
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Old April 15th, 2009, 06:46 AM   #19
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Originally Posted by Steve Mullen View Post
I think I can set you mind at ease. The 100 series uses two 640x720 sensors mounted together so each sensor only had to run at half the data rate as would a single 1280x720 sensor. Less speed = less power = less heat = lower noise BUT, getting both halves to match = not EZ.

I believe the 200 switched to a 1280x720 sensor which eliminated the matching worries, but reversed the equation: 2X faster = more power = more heat = more noise.
Actually the HD200 series and the HM700 all still use the 2x 640x720 with each side being processed separately. How do I know? I can still invoke the "split-screen"... even on the HM700 at +9dB. The improvement happened in January 2006 when JVC QC figured out how to best calibrate the two sides so that the "split-screen" wouldn't show up except in extreme high-gain modes.

The core difference on the front end from the HD100 series to HD200 series was the jump from 12-bit A/D to 14-bit A/D. Of course it all has to go back to 8-bit for Mpeg2, but I think that the 14-bit processing simply holds on to more low-level detail (including fine noise) through the processing that eventually gets passed on to the encoder.
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Old April 15th, 2009, 07:39 AM   #20
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The core difference on the front end from the HD100 series to HD200 series was the jump from 12-bit A/D to 14-bit A/D. Of course it all has to go back to 8-bit for Mpeg2, but I think that the 14-bit processing simply holds on to more low-level detail (including fine noise) through the processing that eventually gets passed on to the encoder.
Thanks Tim, well thats interesting, same sensor set up, but the new improved 14 bit A/D with the 200 series is creating a hotter running camera, an audibly noisier camera, with a visibly noisier picture, any improvement with the hm700?

Maybe the 14 bit A/D via sdi to 8 bit 100meg 422 MPEG2 CODEC (XDCAM HD), to convergent design nano may realise that fine detail more effectively, meaning real detail and not noise. anyone tried this with hd 200's or hm 700's?
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Old April 15th, 2009, 07:59 AM   #21
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...any improvement with the hm700?

Maybe the 14 bit A/D via sdi to 8 bit 100meg 422 MPEG2 CODEC (XDCAM HD), to convergent design nano may realise that fine detail more effectively, meaning real detail and not noise. anyone tried this with hd 200's or hm 700's?
The HM700 seems to be on-par with the HD200, but I haven't tested them side-by-side yet.

I've viewed the HD-SDI output on my LCD HD monitor and the fine noise in the shadow area is still there.
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Old April 15th, 2009, 09:56 AM   #22
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Any suggestion?

Just bought a HM700 but I cannot use it because I'm waiting for the batteries, shipped separatly. As soon as they get here I'll do my tests.. but... I have an idea. I bet that this camera has better (maybe just slightly..but better) light and colour handling than the 200. Also I'm sure that fiddling with gamma and the various settings will let us take out the best from the camera. Sure I think that this camera needs light and we have to talk about that. Good things these digitals have if the ability to save on a file the settings so we could swap user settings or the camera to see which work good (and in what situation).

I have another question. In Italy they would sell me the original JVC quick release bracket to put under the camera when used on tripod (and not shoulder) for around 300 euros that is not little. Can somebody suggest a compatible bracket made by some other brand?
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Old April 15th, 2009, 09:58 AM   #23
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thanks Tim.
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Old April 15th, 2009, 10:46 AM   #24
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Originally Posted by Marcello Mazzilli View Post
I have another question. In Italy they would sell me the original JVC quick release bracket to put under the camera when used on tripod (and not shoulder) for around 300 euros that is not little. Can somebody suggest a compatible bracket made by some other brand?
Well I just ordered the Sony VCT-U14 plate for mine... they're identical plates and the Sony (at least over here in the states) is about 35% less expensive.

Ha, as I was posting that the plate came - works perfectly.
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Old April 15th, 2009, 11:16 PM   #25
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Originally Posted by Tim Dashwood View Post
I can still invoke the "split-screen"... even on the HM700 at +9dB. The improvement happened in January 2006 when JVC QC figured out how to best calibrate the two sides so that the "split-screen" wouldn't show up except in extreme high-gain modes.
I wouldn't call +9dB EXTREME high gain. In fact, I doubt one can shoot in any low light condition at less than +9 or +12dB with a camera with only 1/3" CCDs. Cetainly, not with only 1/4" CCDs. High-level of gain will be mandatory with HM700 and HM100.

The longer A/D would be a perfect way for more noise to enter. (Are you sure it was the A/D and not the DSP that became 14-bits?)

The noise really needs to be IN the values output by the A/D. Which means the CCDs or the A/Ds. And, why the need for fans in the 200 if the CCDs didn't change?

Is JVC still using split-CCDs in the HM100?
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Old April 16th, 2009, 06:41 PM   #26
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Originally Posted by Steve Mullen View Post
Which means the CCDs or the A/Ds. And, why the need for fans in the 200 if the CCDs didn't change?
I understood at the time that the extra heat came from encoding at 60fps in HDV.

the HD100 only did 30p in HDV and 60p was restricted to SD resolution.
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Old April 17th, 2009, 04:39 PM   #27
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Thanks David

For the plate.. Thanks
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Old April 17th, 2009, 05:51 PM   #28
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Noise

I'm starting to do my first tests and one thing I'm not pleased of is the noise. Not only in low light conditions, where I shoud expect it... I see noise in the picture almost everywhere. My old camera was (is) a Sony Z1 which on the paper should be much much worse but I don't get much noise out of it. Am I doing something wrong. Sure, this camera it's much more complex. Any suggestion ?
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