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Dynamic Range, F-stops, RGB, and camera marketing

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Richard Herd
Dynamic Range, F-stops, RGB, and camera marketing
on Dec 9, 2013 at 9:06:16 pm

I'm a little confused by the camera marketing that reads "13 stops of dynamic range." My light meter only has 9 f-stops on it!

Normally, I light like this:

Shadow: 2.8
Fill: 4.0
Exposure/key: 5.6
Rim/backlight: 8.0
Highlights: 11.0

I need help understanding what they mean by "13 stops of dynamic range." Additionally, if this is all 8-bit, where 0RGB=totally opaque and 255=totally white, and middle gray is 127-ish how are the remaining gradient values halving/doubling within that range?

Do I also need to change my f/stop secret sauce mentioned above, using bigger increments in f/stops and therefore purchase new lights?

I hope that makes sense.

Thanks!


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Rick Wise
Re: Dynamic Range, F-stops, RGB, and camera marketing
on Dec 9, 2013 at 9:59:00 pm

I presume by "shadow" you mean shadow with detail, and "highlights" means highlights with details. I am guessing that below "shadow" lies black with no detail, and above "highlights" lies pure white. So you seem to be working with a dynamic range of 7 stops.

"13 f-stops of dynamic range" means your camera will be able to capture details across 13 f/stops. Cameras that have a range of seven f/stops compress both toward the bottom and toward the highlights. If you work with a 13-f/stop camera, you can continue to use your "secret sauce" and get just about the same results you have been getting so far. Or, you can push the envelope further, both at the high and low ends.

Rick Wise
Cinematographer
San Francisco Bay Area
http://www.RickWiseDP.com


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Richard Herd
Re: Dynamic Range, F-stops, RGB, and camera marketing
on Dec 9, 2013 at 10:17:55 pm

Thanks!

(Yes, shadow with detail; highlights with detail)

Creatively and compositionally, what do you do with the rest of the latitude? Are there words that describe them the way "shadow" and "key" are describable by their particular f-stop?


Thanks!
Richard
(BFA MPT AAU, SF 2005 :)


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Rick Wise
Re: Dynamic Range, F-stops, RGB, and camera marketing
on Dec 9, 2013 at 11:16:03 pm

Hopefully you learned about the Zone system at the Academy of Art (where I teach.) That will help you to understand how "shadow" can be anywhere from pitch black to fully textured black, usually a range of 3 f/stops. Equally, on the high side, Zone Vll is fully textured "white" but there are increasing shades of white going all the way to clip (Zone X.) The world is not contained in seven zones. Take a spot meter outside on a bright sunny day and see how many degrees there are from pure black to pure white.

Seven-stop cameras compress all that rich details of light into a few zones, losing all the detail out there. Your "secret sauce" is a very conservative way to approach lighting. When you have a camera that can embrace 13 stops you have lots of room to play, creatively. Try it. You'll like it.

Rick Wise
Cinematographer
San Francisco Bay Area
http://www.RickWiseDP.com


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Richard Herd
Re: Dynamic Range, F-stops, RGB, and camera marketing
on Dec 11, 2013 at 12:03:28 am

Thanks! I'm definitely familiar with zone (in Anjali's class).

For example, though, today I shot on f/4 and the camera zebras set to 100% show up at 8, and the wave form monitor showed the highs at 125%. I"m not sure what to believe anymore! The color correction software still allowed me to pull things into broadcast safe. So I'm struggling with a creative challenge, I guess. What on earth would I put in those high-lights, if I had additional stops?

(Also note, I like to mix color temp, so that the key is tungsten (the white balance), the hair light, for today, was daylight, and the background light was daylight with a 1/2 sheet of yellow gel. I'm not sure if that affects/effects the above mentioned zones, ergo yellow adding contrast in the luminance the way yellow adds a sky in b/w film-photography.)

(I know you teach there, hence I added my alumni info.)

Thanks again!


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