Who said the VG20 does not have -ve gain? - Page 2 at DVinfo.net

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Old June 20th, 2013, 03:12 PM   #16
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Re: Who said the VG20 does not have -ve gain?

That was my point, even with negative gain the shutter will still go through the roof at bright sunny days to compensate so I don't see the advantage really? From what I understood negative gain was particularly useful for smaller sensor camera's, which had that option, to reduce noise as much as possible.
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Old June 20th, 2013, 04:01 PM   #17
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Re: Who said the VG20 does not have -ve gain?

Gain is set at what the designers decide , it isn't an absolute value. My NX5U has negative gain to -6db and being an ex marketing person myself I suspect that was to give it a good sensitivity at 0 db for the competition( ie 0 is actually 6db), who likely were all doing the same thing to make the test look good !!! Probably explains why the picture is full of noise at 12db !!! Running the NX5U in auto the gain often sits at -3 or -6 db and even in the theatre will sit at 0 db. Watching the NX5U or for that matter the smaller Sony's they will vary iris and gain keeping them at what is clearly known by the designers to be the sweet spot for the lens. They do not simplistically open iris then increase gain. They both move together sometimes in opposite directions !! When it gets bright the shutter speed also comes into the picture so now there are more parameters to play with and yes I have seen on the XR500 ( which is what I used to find all this out when I first got it ) shutter at 1/250, gain at 6db and iris at F4 !! Not something I would set in manual. But there must be some reasoning, perhaps something to do with the steadyshot as I was walking down a path in the sun in that case.

With the Sony's if just one of the parameters is in auto the camera has control. If they are all in manual then AE shift will not work or any of the other scene presets. Which is why I asked Craig to check the data code on playback. Like Chris I expect the shutter speed is compensating for the fact it has reached limit on gain and cannot control iris with the manual lens.

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Old June 20th, 2013, 05:02 PM   #18
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Re: Who said the VG20 does not have -ve gain?

"Ron Evens: Not something I would set in manual. But there must be some reasoning, perhaps something to do with the steadyshot as I was walking down a path in the sun in that case. "

Ron, Your giving the camera way to much credit! NEX does not mean NEXt it will be making your coffee for you in the morning. Camera GPS will not show up on your viewfinder as Google maps no matter what settings you use! And no matter how many times my wife asks....there is no such thing as a skinny lens!!!

Just kidding...I could not resist a little humor. You bring up a good point about 0 gain being arbitrary. If it is not a known factor then what good is it for comparison sake? I never realized it is not a given!

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Old June 20th, 2013, 05:43 PM   #19
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Re: Who said the VG20 does not have -ve gain?

Quote:
Originally Posted by Steven Digges View Post
.. You bring up a good point about 0 gain being arbitrary. If it is not a known factor then what good is it for comparison sake? I never realized it is not a given!

Steve
No use what so ever. If a camera is great at 0db but has lots of noise at 9db and another is less sensitive at 0db but has no noise at 18db which is the better camera. Cannot tell from the numbers, only what pictures they will take in different conditions not what the numbers they are using to get that picture. Engineers decide how the electronics work and I suspect the marketers decide what the numbers are to show !!! Comparisons of the cameras I have used and rented have convinced me not to take the numbers too seriously at all. When I rented Panasonic cameras they appeared to be very sensitive compared to the Sony but had lots of grain above 6 db with some of them !! Technology changes too. The little Sony's almost see in the dark with no noise where the NX5U with negative gain is almost useless above 12db ( is that really 18db ? ) and at that point I have to use NEAT video filter to make the video usable, or least acceptable compared to the CX700 or the NX30U which in the same conditions are indicating 21db with almost no noise !!!

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