What Film Looks Like

[Darren Weckerle]

I’m a young aspiring DP who’s never actually seen or touched film, all I know is from what I’ve read or heard. The trouble is that everything I’ve read or heard assumes I know about film from experience, so certain things are never really explained.

So, when it comes to a traditional photochemical workflow (no DI), I’m confused about a couple things and curious about another.

First, what does correctly exposed negative film actually look like? Okay, I’ve Googled photos of film negative, so I know what it “looks like” in that sense, but what I mean is, if I could hold it up and see it through a positive filter that otherwise applied no other adjustments, what would I see: a positive-color image that looks like a LogC Alexa image, or a positive-color image that looks like a Rec. 709 Alexa image? And depending on the answer to that, does print film apply an S-curve to the flat, log negative image to make it look proper, or does the print film simply increase the saturation and contrast by a bit more to what is otherwise an already colorful and contrasty negative image?

Second, what is the effect of the interpositives and internegatives separating the original camera negative and final release print? Compared with creating a release print straight from the original negative, what do the steps in between generally tend to do to the image?

Here’s where my confusion comes from:

I keep reading about digital cinema cameras recording with Log encoding to mimic what negative film scans look like, making it sound like film negative actually records a flat and washed-out image. But when I first learned about film and how it works, I was led to believe that it responds to light with an S-curve pattern, where the emulsion doesn’t respond very much to low levels of light until a certain threshold of irradiance is reached (the top of the toe), after which it responds fairly linearly (each additional stop of light reaching the film causes the emulsion to become twice as dark), until another threshold is met (the bottom of the shoulder), whereafter each additional stop of light reaching the film causes only a slight increase in exposure. Taken together, this would mean that, apart of inverting the colors and light for dark, negative film has deep, rich blacks and smooth, rolling highlights… the film look. But from my recent reading it seems this is incorrect, and instead, the “film look” is much more to do with the print film, which essentially applies an S-curve to the flat-looking log image of the negative.

But which is true?

And to confuse matters a bit more, I am aware that film is both a capture medium, recording light, but also the display, showing an image just like a printed picture (which it technically is). So the film could theoretically respond to light in one way (log, linear, or S-curve) but actually display the image it captured in another way entirely, like a display with a different gamma than the image (log, linear, or S-curve). So what is the relationship between how film responds to light compared how it displays that light?

Thank you so much for clarifying this and filling the gaps in my knowledge!