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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Remember the attitude towards latitude!

Brook Willard said:
This may have changed... remember, this was calculated from Frankie.
Click to expand...

So, if I'm reading that right, Frankie was showing about 11 stops, as has been discussed...
 
Does anyone know what the units are on the chart under brightness (the ones that go from 0 to 12). Is it foot candles? I apologize if this is a dumb question but I would really like to know.
 
I was assuming that was just relative exposure in f-stops, based on the caption "STOPS". If it was a linear unit like footcandles that would be an extremely small dynamic range. Opening up the lens by one f-stop increases the effective area of the lens by a factor of two, resulting in twice as much light reaching your image plane (film or sensor). So 11 stops is a range of 2^11 to 1, or 2048:1 in light intensity.

Another way to think of it: 11 stops difference in light is roughly the difference between a floodlit building at night and direct sunlight on a clear day. At least according to this chart: http://www.fredparker.com/ultexp1.htm#Light Intensity Chart
 
Relative to what? The horizontal numbers I asume are f-stops since it says 'stops' and because there is a hard grey vertical line at around 2.2 and 13.6 or so... But what are thevertical numbers. I come from an audio background and I am used to looking at response charts... but this one I still can't figure out.
 
Oh, the vertical "brightness" scale. I assume that's just the output of the camera, on a log scale, in arbitrary units. I believe the point of the graph is just to show that there is some response which extends over 11 stops, not a specific calibration.

At least in the video camera world I have not seen a camera output calibrated directly from IRE units to say footcandles. Because of the gamma curve, "knee" and various compression curves, the response is very non-linear. You could match up one specific output value to one input light level, but to extrapolate that to other levels it's a rather complex function.
 
Okay, not to be the devil's advocate, but what stops a manufacturer from just plumping the curve to make it look better if the numbers don't mean anything? In the audio world you sometimes have manufacturers that compress down the db spread on their response curves just to make the measurement seem very flat... but at least they still disclose that it is in db increments that they are measuring.

I am sure Red will eventually have all charts available with acurate measurements, it's just that I was trying to understand this particular one.

EDIT: oops, didn't see Brook's post with that link. I will read right now.
 
My take is the graph indicates there is "some response" over the indicated range of f-stops but we don't currently know exactly "what response". It's a sort of quick visual answer to the question of "how many f-stops of dynamic range" which lots of people had been asking, to which the graph answers "11+".

I believe you are asking a more detailed followup question, which is fair, but the graph by itself doesn't fully answer. That awaits further info from Red. At the bottom limit the usable dynamic range is always fuzzy because it depends on what noise level you are willing to tolerate; a very subjective thing.
 
I don't know what the numbers refer to. That's why I said I'd leave it for somebody from RED.

On a side note, I'm doing a test with 5212, 5217, 5218 and 5299 in two weeks to compare, among other things, grain structure and dynamic range. The negatives will be scanned at 2K and all sorts of fun will be had. If I can get my hands on a T4110 C by then, you'll have an interesting "Frankie vs. Kodak" comparison to read about.
 
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