Histogram, Shmistogram

Bill Ravens · January 16th, 2009, 08:18 AM

I am only suggesting playing with the aperture so that the poster can convince himself that his shadows aren't above the left wall. I am not suggesting that intentionally under-exposing is a way to increase dynamic range.

However, in keeping with my original comment, to maximize dynamic range on the EX1, first thing is to use a gain setting of 0 dB. If this is too hot, use an ND filter. Now, maximizing dynamic range is frought with problems, like leaving no headroom for exposure errors. Great for well controlled(aka well lighted) stage, but, not so great for run and gun. In the case of run and gun, I would try one of George Strother's presets.

Andrew Stone · January 16th, 2009, 11:57 AM

Quote:

Originally Posted by Bill Ravens

In the case of run and gun, I would try one of George Strother's presets.

Would you be referring to this post of his, Bill?

Bill Ravens · January 16th, 2009, 12:11 PM

yep.... that would be it

Keith Moreau · January 16th, 2009, 01:43 PM

Quote:

Originally Posted by Bill Ravens

Keith...

A couple of comments....
1-You can play with the aperture to intentionally under-expose. I would expect this to force the histogram to the left, just to see if the brick wall you're complaining about is real.
2-The histogram Sony provides is only 25% of the story. Better histograms will also show the individual RGB channels. It's possible to over/under expose a scene in only one channel, like Blue, and not have it show up in a composite histogram on the camera. The method of importing into Photoshop, described above, would verify whether or not that's what you're seeing.

from a later post: However, in keeping with my original comment, to maximize dynamic range on the EX1, first thing is to use a gain setting of 0 dB. If this is too hot, use an ND filter. Now, maximizing dynamic range is frought with problems, like leaving no headroom for exposure errors. Great for well controlled(aka well lighted) stage, but, not so great for run and gun.

Thanks for the advice, Bill, yes I've tested the left 'wall' by reducing the aperture to closed. The brick wall is still there, just like on the right side with certain PP and Gain-3. Any clues? I'll also test out using Photoshop on an image.

Regarding using 0 gain rather than -3 gain, am I hitting a brick wall anyway with -3 Gain, just sooner with -3? Also am I trading off more noise at the 0 gain setting? It seems like everybody recommends -3 gain setting, but, really, what are the advantages? Thanks for yours and everybody's input.

Bill Ravens · January 16th, 2009, 02:08 PM

On the contrary, the way the gain is defined during manufacturing, the voltage that produces the lowest noise is 0 dB. Other gain values, above or below, should increase noise.

Looking at the left edge of the histogram on my EX1, I notice that zero signal corresponds to a position on the histogram that is about 1/16-1/8 inch to the right of the left frame edge around the histogram window.Perhaps you're assuming that the display should extend all the way to the left frame, when, in fact, it does not. You can test this by turning on the TestBar pattern and notice where zero is.

Bill Ravens · January 17th, 2009, 12:22 PM

Keith...

Dunno why I wasn't thinking when I answered you, yesterday. The brick wall, on the left of the displayed histogram, can be moved left or right by the BLACK setting in the Picture Profile menu, under BLACK. Note that the default setting of '0' gives you some small amount above RGB16. I found that setting '-8' is pretty close to an RGB of 16. A setting of '-16- seems to be the lowest my camera will go before it starts to crush the blacks, according to my Waveform Monitor.

Keith Moreau · February 4th, 2009, 12:44 AM

Quote:

Originally Posted by Bill Ravens

Keith...

Dunno why I wasn't thinking when I answered you, yesterday. The brick wall, on the left of the displayed histogram, can be moved left or right by the BLACK setting in the Picture Profile menu, under BLACK. Note that the default setting of '0' gives you some small amount above RGB16. I found that setting '-8' is pretty close to an RGB of 16. A setting of '-16- seems to be the lowest my camera will go before it starts to crush the blacks, according to my Waveform Monitor.

Bill, I played with Cine4 and reducing the black setting from 0 to -5, -10, and beyond and the brick wall on the left did not move to the left. Increasing it above 0 did make the left brick wall move to the right, I suspect crushing the blacks further. I guess what I'd like to see is to be able to use Cine 4, 0 gain for no brick wall on the right, and some setting that would allow me to have no brick wall on the left. This way I hope to maximize my lattitude on the darkest and brightest scenes. I feel like I'm throwing away valuable image information now. Any clues? Thanks.

Keith Moreau · February 4th, 2009, 11:03 PM

I just played around with a lot of picture profiles and gain level with the Black level and nothing I do will move the left brick wall all the way to the left when I close the iris. It's as if this is just an unused portion of the histogram. Bill or anybody else, if you can get the left brick wall to go all the way please let me know. Or maybe I shouldn't worry about it --however I figure I'm throwing away some detail in the shadows. My aim is to be able to squeeze every bit of available latitude I can. Thanks all.

January 16th, 2009, 08:18 AM	#16
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	I am only suggesting playing with the aperture so that the poster can convince himself that his shadows aren't above the left wall. I am not suggesting that intentionally under-exposing is a way to increase dynamic range. However, in keeping with my original comment, to maximize dynamic range on the EX1, first thing is to use a gain setting of 0 dB. If this is too hot, use an ND filter. Now, maximizing dynamic range is frought with problems, like leaving no headroom for exposure errors. Great for well controlled(aka well lighted) stage, but, not so great for run and gun. In the case of run and gun, I would try one of George Strother's presets.

January 16th, 2009, 12:11 PM	#18
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	yep.... that would be it

January 16th, 2009, 02:08 PM	#20
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	On the contrary, the way the gain is defined during manufacturing, the voltage that produces the lowest noise is 0 dB. Other gain values, above or below, should increase noise. Looking at the left edge of the histogram on my EX1, I notice that zero signal corresponds to a position on the histogram that is about 1/16-1/8 inch to the right of the left frame edge around the histogram window.Perhaps you're assuming that the display should extend all the way to the left frame, when, in fact, it does not. You can test this by turning on the TestBar pattern and notice where zero is.

January 17th, 2009, 12:22 PM	#21
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Keith... Dunno why I wasn't thinking when I answered you, yesterday. The brick wall, on the left of the displayed histogram, can be moved left or right by the BLACK setting in the Picture Profile menu, under BLACK. Note that the default setting of '0' gives you some small amount above RGB16. I found that setting '-8' is pretty close to an RGB of 16. A setting of '-16- seems to be the lowest my camera will go before it starts to crush the blacks, according to my Waveform Monitor.

February 4th, 2009, 11:03 PM	#23
Keith Moreau Major Player Join Date: Nov 2006 Location: Brisbane, California Posts: 530	I just played around with a lot of picture profiles and gain level with the Black level and nothing I do will move the left brick wall all the way to the left when I close the iris. It's as if this is just an unused portion of the histogram. Bill or anybody else, if you can get the left brick wall to go all the way please let me know. Or maybe I shouldn't worry about it --however I figure I'm throwing away some detail in the shadows. My aim is to be able to squeeze every bit of available latitude I can. Thanks all.