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Vision3 real/usable dynamic range

dynamic range DR film vision3 kodak scan 16bit

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#1 guillermo cameo

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Posted 11 September 2016 - 10:40 AM

Hello, this is my very first post on this forum so first of all thank you all for having some time to read and answer this question.

I'm going to shoot a project on S16 (arri 416 plus) next month and I don't have nearly the same experience with film than digital so I'm sorry if this sounds really newbie.

 

Basically I'd like to know what's the real and usable dynamic range of kodak Vision3 and all the elements that affects it (print, scan, etc). I Research on this forum, internet and on Kodak's website and the numbers change considerably. Kodak says it's about 10-11 stops, then I read that the official number is 14 (this is hard to believe) and some friends told me it's about 7 stops (-3, +4).

 

Also I wanted to know if the print and the scan are really important to save the dynamic range. I read a Kodak document that recommends to use 16bit scan when the stock is Vision3 to hold all the dynamic range in there. Also, which scanner do you recommend me? What I read the best one is DPX 16bit but it may be really expensive so I'd like to have a cheapest solution that can hold the DR of the film.

 

Thanks!


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#2 David Mullen ASC

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Posted 11 September 2016 - 11:44 AM

There's a difference between dynamic range on the original versus how many stops can appear in a print or on a Rec.709 monitor, which is a much smaller number.

 

This isn't a bad thing because it allows you a lot of flexibility to color-correct the image or adjust for exposure mistakes, plus if using digital color-correction tools, you can selectively pull more information into areas where you need them.

 

14-stops is about right for color negative in terms of the range from the darkest information near the base fog level and the brightest information in the shoulder before things hit D-max.  But that last stop of shadow information is fairly grainy so you are limited if you want to pull it up, usually it falls outside the range of the display device or print.

 

For practical purposes, you can imagine that you have a 10-stop range that will be displayed but a log scan will capture all 14 stops, so when you start color-correcting using a log-to-Rec.709 display LUT (or whatever you're final display will be, could be a P3 DCP projector rather than a Rec.709 HD monitor, or a film print) you will only see that smaller range but the colorist can pull up information from the complete range (though again, you might not find that the extreme ends look great when you pull them up or down too much.)

 

Most common format for scanning movie film would be Cineon 10-bit log, uncompressed RGB DPX files.

 

The only caveat is that an HDR master would display all 14-stops of information.

 

If you shoot an over and underexposure test and make a normal print of it, you find that you have about 4-stops below and 5-stops over to work in, that appear in the print, but those extreme ends are rolling off into blackness or white. But if you are lighting a dark scene, it's good to know when things fall off into black.  But if you are doing a D.I. you aren't limited as much to the display contrast, you can flatten out a scene or increase the contrast, within limits before you start seeing grain problems.


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#3 guillermo cameo

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Posted 11 September 2016 - 02:39 PM

Thank you so much for the extensive explanation, David.

Now everything looks clearer!


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#4 Robert Houllahan

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Posted 11 September 2016 - 05:06 PM

I would also consider that film is an organic medium and can be stretched to good visual effect, we have had people shoot ECN at 5 stops over and pull it back in post to get a weird thin look, something you wouldn't get with digital. Similarly look at how the Godfather got it's look and that was not really changeable by the studio because of how it was shot under.

 

I thought the official lets race the medium around the test wedge put Vision3 stocks at 16 stops but then everyone has their specs.

 

As for scanning there are actually very few scanners which have sensors that are 16-bit in the A/D and have the S/N to make the 16bits real. Many very high end pin registered scanners use 14-bit sensors.

 

Many new fast scanners use 12-bit CMOS sensors with relatively high S/N ratios and post processing in the scan.

 

YMMV


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#5 David Mullen ASC

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Posted 11 September 2016 - 09:27 PM

Kodak used to claim 15 stops for Vision but pulled it back to 14 stops in their literature and in interviews with the Kodak leadership. Often people cannot decide whether to count the bottom step or not, the one buried in the base fog level (or the noise floor in a digital camera.)


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