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Old May 13th, 2011, 08:31 AM   #1
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HPX371/370 noise and skew update

Hy!

I've read somewhere that the update which supposedly fixes the noise issue on the 370/371 reverts the camera basically to the previous model 300/301 regarding noise. Has anybody else hear or read something similar? Or could a owner of the 370 who did the upgrade share some knowledge regarding this topic please. What was causing the problem anyway? Was it maybe something to do with skew removal - if so could it be that the skew is worse with the upgrade applied? Or was it just a problem with temporal noise filtering...?

I'm seriously thinking of buying this camera but won't do so until I get some answers on this matter. Every where I look on the internet the reviews of this camera are off-course done with the factory firmware so that makes them in effect (if the above is true) false. At least regarding the noise issue (and maybe skew)... Did Panasonic put new chips in this camera or did they just ad some fancy noise removal algorithm?


S.Š.
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Old May 13th, 2011, 09:17 AM   #2
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Re: HPX371/370 noise and skew update

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Originally Posted by Sanjin Svajger
What was causing the problem anyway? Was it maybe something to do with skew removal ......
Didn't seem to be anything to do with skew. The basic issue seems to be 1920x1080 res chips which are 1/3" - it makes each photosite that much smaller, which means a tendency towards a higher noise figure.

And that was the basis of the complaints against the 301 - tendency to be noisy, certainly with gain applied. The 371 was brought out as the answer to those complaints, and at first sight seemed an improvement. But it seems the improvement is not through inherently better chips, but a noise removal process, which includes a form of frame by frame smoothing.

That does seem to work very well on static subjects - but gets somewhat fooled by movement. The result is that a moving object can be trailed by a "noisy ghost". The effect is quite low level - but quite irritating when you're aware of it. I heard of the problem just before we got a 371 to test, and whilst not immediately obvious, it didn't take long to see it on normal, 0dB pictures.

It didn't seem too serious at first - until we looked at chromakey performance. What might be only slightly noticeable on straightforward pictures made it completely unusable for some chromakey tests, and I think it would not stand up well to other forms of post manipulation either.

Eventually the issue was acknowledged - and (as you say) the "fix" was to offer the option of doing away with much of the noise reduction. Exactly what had initially been brought in to address user criticisms about the 301.

It has to be said that the 371 is a relatively cheap camera, and it may be asked "what do you expect for the money?" It's a fair point, but we looked at the Sony PMW320 at the same time, and when you take memory etc costs into account, the relative prices were at least in the same ball park - they're both pretty cheap for pro-style shouldermount cameras. But our conclusion was that the only real advantage the 371 had over the 320 was a better codec - which didn't make up for the poorer front end of the 371. The 320 also seemed better in respects of viewfinder etc.

And since you can add an external recorder to the 320, whilst you can't do anything about the 371 front end, the conclusion was that the 320 was (overall) the better of the two, certainly with the pricing at the time - don't know if it's changed since.
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Old May 13th, 2011, 12:26 PM   #3
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Re: HPX371/370 noise and skew update

A lot of then problems were when the camera was set or used in NTSC mode the PAL operation was very acceptable and if you read the two reports from Alan Roberts he says the 301/371 camera's are virtually the same.

I have never had a problem with noise on my 301 and have it set up as per the BBC report, it is now fully approved for BBC HD shooting and after two years of use I can not fault it for the money, the skew and noise are worse at NTSC and 24p shooting but as I rarely or never do this it is not a problem.
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Old May 13th, 2011, 01:48 PM   #4
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Re: HPX371/370 noise and skew update

So if I understand this correctly: the noise/picture quality between this two cameras after the update is negligible - the biggest difference is in the skew?

I'm just thinking if there is no difference between this two cams (if the skew is the same) then why go for the 371?? If the skew is better on the 371 then for me it's a no brainer - I'm allergic to skew and jello. Personally I think that cmos chips with slow rolling shutter readouts have no place in a ENG type camcorder. ENG style of filming is prone to fast pans and zooms, shaky footage, etc., etc. This kind of filming is then prone to skew and jello... I understand if you plan to use this camera in a studio or in any kind of manner where the cmos chips won't produce skew or jello...

Anyway not to get to much off-topic: is the skew still better on the 371 after the update? On the 301 was the skew only problematic in NTSC not in PAL? I am in PAL land btw.

Thanks for the answers guys!:)
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Old May 13th, 2011, 02:14 PM   #5
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Re: HPX371/370 noise and skew update

I think most of the improvements on the 370/371 related to NTSC, I have noticed worse skew on my 301 at NTSC 24p but I think for PAL use you are OK just getting the 301 as any difference with the 371 does not seem to have been reported.

The skew is very good at 25p and if you follow film panning speeds it is as good as cmos gets and I have not noticed it very much at 1080 or 720 shooting, the noise is also OK if you do not go over +6db of gain.
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Old May 14th, 2011, 04:10 AM   #6
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Re: HPX371/370 noise and skew update

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you are OK just getting the 301 as any difference with the 371 does not seem to have been reported.
.
Really? I must investigate into this further...
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Old May 14th, 2011, 04:17 AM   #7
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Re: HPX371/370 noise and skew update

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Originally Posted by Sanjin Svajger View Post
Really? I must investigate into this further...
Yes I have not heard any reports that the 371 is better than the 301 in PAL mode, certainly it improved the NTSC and 24p performance but even Alan Roberts said in his reports that they were virtually the same:

301: http://thebrownings.name/WHP034/pdf/...nic_HPX301.pdf

371: http://thebrownings.name/WHP034/pdf/...nic_HPX371.pdf

I questioned if panasonic had actually put a new sensor in like they claimed or just put an extra level of filtering but it all went very quiet one they had to release a firmware update which virtually made it a 301 again.
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Old May 14th, 2011, 08:55 AM   #8
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Re: HPX371/370 noise and skew update

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but it all went very quiet one they had to release a firmware update which virtually made it a 301 again.
It did didn't it!? I was looking into the 371 when the noise issue was reported... But then when the firmware update came along nobody said anything about it. Nothing from users and nothing from Panasonic - or at least that's my impression.

Thanks for the links!
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Old May 14th, 2011, 09:04 AM   #9
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Re: HPX371/370 noise and skew update

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Originally Posted by Sanjin Svajger View Post
It did didn't it!? I was looking into the 371 when the noise issue was reported... But then when the firmware update came along nobody said anything about it. Nothing from users and nothing from Panasonic - or at least that's my impression.

Thanks for the links!
Glad to help, there were two nearly new 301's advertised on here but they seem to have gone now: BB LIST - CATEGORIES
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