Accuracy of H4D LCD Histogram

[Michael H. Cothran]

When I owned my CFV back, I discovered early on that the histogram on the CFV was not the same as that in my post processing software. Trying to expose to the right, I discovered that what looked good on the back's histogram was right-clipping in PS.
I was instructed (cannot remember the source) to lower the brightness and contrast of the CFV back. It defaults with settings of 5/5. I lowered them to 0/0, which, in turn, gave me histograms that more closely resembled those in PS.

When I received my new H4D, the first thing I did was lower the contrast and brightness of the back's LCD panel to 0/0 again. In bright light outdoors, with a "normal" exposure, I can hardly see the image, but can see the histogram and other menu functions fine.

So now, I'm wondering whether or not this issue pertains only to the CFV backs, or are other LCD histograms subject to level changes made by brightening or dimming the image screen? I have not yet taken the time to closely compare the back's histogram with that of Phocus or PS, but that might be a good project for this coming weekend.

Also, do you think that keeping the LCD dimmer weighs in very much on battery conservation?
Thanks

[KeithL]

So now, I'm wondering whether or not this issue pertains only to the CFV backs, or are other LCD histograms subject to level changes made by brightening or dimming the image screen?

I'd be worried if the accuracy of any histogram depended on the brightness of the LCD screen. I admit I may well be wrong, but I just don't understand the possible relationship between the two.

What I do see is that the values displayed on the camera histogram don't always match the values displayed in Phocus and the values displayed in Phocus don't always match the values displayed in Photoshop. 

[Michael H. Cothran]

"I'd be worried if the accuracy of any histogram depended on the brightness of the LCD screen. I admit I may well be wrong, but I just don't understand the possible relationship between the two.[/quote]

What creates the histogram on the camera screen? I was told that it is created from the image being displayed (not the RAW file data), and if that image is modified with brightness and contrast, it will affect the histogram.

An easy way to find out is to make an exposure, then adjust the brightness and contrast of the screen, and watch the histogram. I plan to do just that with my first opportunity.

I know that with my CFV, once I toned it down, my histograms more closely matched.

[KeithL]

Gosh, I hope you're wrong.

[KeithL]

But bottom line, adjusting the brightness on the LCD would not affect the histogram.

Phew! 

[Michael H. Cothran]

I just tested my histogram, and I see no difference. Might as well adjust it back to 5/5, and be able to see it.

[NickT]

Yep what Derek and Keith said.

The histogram *used* to be taken from one channel only (green from memory), not sure if that is still the case, David?