DVX-200 High Sensitivity Mode

[Bruce Lomasky]

Can anyone tell me what this does compared to pushing up the AGC?

Thanks

Bruce

[Joachim Claus]

With DVX200 you have three gain controls:

1. In automatic settings (AGC), gain is automatically set between 0 and 24 db.

2. In manual mode you have the usual switch operated gain settings, with L (low), M (medium), and H (high). The values can be set-up between 0db and 24db. Default values are L=0db, M=6db, H=12db.

3. Setting the camcorder to High Sensitivity, you set gain to either 30 or 36 dB (menu selectable).

Joachim

[Bruce Lomasky]

Sorry that is incorrect.

You are answering what "Super Gain" (pg 151 in manual) does. and that is on the SW menu.

On the System Mode Menu, last choice is: "High Sens. Mode"

The manual says: use this setting when recording in a dark environment. It "LOOKS" like it boosts luminance, but not sure.

Bruce

[Joachim Claus]

Bruce,
I see your point. I will find it out, when I get my DVX200 delivered. May be - but this is speculation - the "High Sensitivity Mode" sets a number of parameters of the camcorder to fit to night shots, comparable with a kind of a scene file.

Joachim

[Barry Green]

Originally Posted by Bruce Lomasky

It "LOOKS" like it boosts luminance, but not sure.

The HIGH SENSitivity mode is a way to double the sensitivity of the camera. The exact procedures used are not known, but from observation I can tell you that it looks to me like it applies about 6dB of gain, and then uses stronger noise reduction to compensate and bring the visible noise level down to about what it was at 0dB of gain.

In my testing it seems to work rather well; you do have to be aware of what gain and noise reduction do, as you may see a tad of flattening of colors due to gain, or some loss of fine high-frequency detail due to noise reduction.

[Bruce Lomasky]

Thanks for the response Barry

Last week, I was @ a 3 day music festival in a hotel meeting room with no windows, NO outside lights, just the spots in the ceiling. So I had time to play and see what worked the best with almost no light. My results with 6db gain and high sensitivy looked MUCH better than 12db of gain and regular.

but it did not seem to bring up the shadows as much as plain, old, ordinary gain did.


(waiting patiently for you book!)


Bruce

[David Heath]

Originally Posted by Bruce Lomasky

My results with 6db gain and high sensitivy looked MUCH better than 12db of gain and regular.

but it did not seem to bring up the shadows as much as plain, old, ordinary gain did.

Which sounds as if it's modifying the gamma curve to apply gain over most of the curve - but less in the blacks.

Which I suppose is along the lines of what Joachim said - "comparable with a kind of a scene file"?

I'd be interested to see what the difference looks like at higher ratings, such as 24dB on low sensitivity setting versus 18dB on high sensitivity. (Which should both correspond to about ISO8000.) I'd expect both to be very noisy, but does the high sensitivity mode still look a lot better?

[Barry Green]

Not really; at 18dB/High Sens vs. 24dB/Norm Sens, they look about the same.

[David Heath]

Thanks - that is what I'd expect if the previous assumption is correct "if it's modifying the gamma curve to apply gain over most of the curve - but less in the blacks".

At low gain levels the noise would be most noticeable in the blacks, so effectively crushing them will give a cleaner look at the expense of shadow detail. At higher gain levels the noise will be noticeable throughout the luminance range, so the technique then having much less benefit.

It sounds like a valid technique if the footage is to be used directly as shot, but if subject to any grading or post I'd think the "High Sensitivity" mode may be a bad idea? Better just to put in 6dB of gain in normal mode, and then do something similar in post - when the amount is under control and not burnt in?