Film latitude and exposuring

[Yusuf Aslanyurek]

Hello,

 

here is DEMO

(Chosing the right film stock)

 

 

Latitude of new generation films have (except Fuji F400 and Kodak Primetime 640) gamma 0.50-0.55 that means 6-7 stops latitude.

-3.5stop is black and +3.5 is white

but this pictures shows face -3 stops and face is still close to grey more that black!

 

I coulnt understant which stock is it? how it can this face +0.6 -3? digits seems to contrasty for day.

[David Mullen ASC]

I don't know if the gamma necessary tells you the dynamic range, just the degree of the slope of the straight line portion of the curve. But Dominic or John can answer that one better than me. But practically, I'd say that modern color negatives have more like a workable 9-stop or so range, from about 4 under to 5 over.

[Dirk DeJonghe]

One important issue to consider is how will the negative be shown; via direct print on film, via telecine on video or via scanner to recorder to print?

 

The negative has far more latitude than any of these routes is able to reproduce. In making a print the DOP and the grader really decide which portion of the negative information will be used and which portion will be discarded.

[John Pytlak RIP]

The "straight line" portion of a modern color negative film's characteristic curve often approaches 3.0 log exposure units (10 stops). But the "toe" and "shoulder" portions of the curve are still capable of capturing extreme scene detail. As Dirk notes, not all this detail will end up on the screen (print or telcine transfer, which both have more limited dynamic range), but it is there to be used if needed.

 

Here is a link to a typical sensitometric curve:

 

http://www.kodak.com/global/images/en/moti...e/5218Sensi.gif

 

Edited November 15, 2004 by John_P_Pytlak

[Dominic Case]

"Dynamic Range" or "Useful Exposure Range" of a typical negative stock is at least 10 stops, as John's graph shows (3.00log E range is 1000:1 or ten stops).

 

A lower gamma can potentially help to increase that range, as a lower slope means it takes longer to reach the top.

 

"Latitude" is, more strictly, the amount by which you can vary your actual camera exposure and still have a printable negative with all the required tones reproduced correctly. Obviously it depends on the Brightness Range of the scene itself as well as the Dynamic Range of the stock.

 

A monitor, or a projected print, has much less brightness range than the negative can recod in the first place. The scenes shown in the Kodak link at the start of this thread don't use the full 10 stop range, as it couldn't be shown. Some of the additional range is taken care of by the toe and shoulder of the sensitometric curve (see John and Dirk's previous replies). Even so, there is usually a lot more information on the negative than the grader or colorist can get onto the print, giving the opportunity to go further into the highlights OR the shadows if desired.

[DavidSloan]

Hey Mr.Case:

 

I just picked up your book, today. Looking forward to reading it. Thanks for sharing your knowledge :)

[Yusuf Aslanyurek]

(I coulnt find char of delta thats why used '|')

(G Gradient, D density)

 

G= |D / |LgH

| Density = Dmax - Dmin

|LgH= |D / G

 

 

 

 

Gradient - latitude (stops)

0.3 - 11

0.45 - 7.3

0.5 - 6.6

0.55 - 6

0.6 - 5.5

0.65 - 5

0.8 - 4

1 - 3.3

 

 

our stocks are 0.5 right? it can capture 20 stops anyway we can print 7 stops.

but in this picture (in first msg) 4 stops contrast on the face and face still plastical (I mean no contrast)

 

soon i will test it myself and develop it in Salamandra (kodak certificated)

[Phil Rhodes]

Hi,

 

> The scenes shown in the Kodak link at the start of this thread don't use the full

> 10 stop range, as it couldn't be shown.

 

This is where I always think it becomes interesting, because said range could be shown if you're willing to compress it - this being the only real purpose of shooting film for video finish, of course. If you actually want the monitor to display ten stops range linearly then again it could do it, depending how dim you're willing to decide that the bottom levels are!

 

At this point you get rapidly into strapping a probe on the front of the display and measuring the actual light output of whatever it is and making a call as to how you want to map data on negative density (a scan) into what the monitor can display.

 

Phil

[Tenolian Bell]

It's pretty rare to actually be in a situation where you actually need to show 10 stops of range in a single image. I think its more the fact that 10 stops are there to be used is the point.