Although within the Digital Intermediate, we do not really need to worry what capture medium the project was recorded on, it is useful to have a small understanding of what film stocks are used and how they look. The reason I believe this is quite important, as a colourist/specialist we have to grasp and understand what the client is asking for, the look or style that their vision is heading towards. It is useful to research the look and feeling of many different film stocks from past generations, as you never know when someone just might ask "do you know what Kodachrome 8mm looks like?"
(A Kodachrome 8mm reel shot by George Jefferies of President John F. Kennedy, just 90 seconds before his assassination in 1963 was discovered in 2007, hopefully this gives an indicator in your mind of what it looks like.)
In my opinion it is useful to work with the production company from the start, as they make decisions on many influencing factors. For instance they may want to be the first to test a new camera or piece of equipment, getting bogged down trying to make it work, when a tried and tested method may be a cheaper solution and look infinitely better.
"I worked on a project which fortunately was in pre production – they approached with the idea they wanted to create a ‘Spaghetti Western’ style. Unfortunately they had already decided they were using a digital camera (influenced by their previous production). The imagery was extremely clean, bright and a million miles away from their intended look.
I managed to eventually arrive at the look they wanted, however as I took them through the post production process, which was time consuming it was obvious it would take a lot longer to produce, costing the production money and time. I previously had worked on a short in Italy using original ‘2 perf’ cameras, spaghetti westerns utilised 2 perf back in their heyday. I showed them some of the original untouched stills, grading them to give the look of what I felt a ‘spaghetti’ should look like, more importantly the look that they had envisioned.
In short, it made no sense financially for the production company to shoot in a digital format, post producing their intended look. Especially when you could still use the original 2 perf cameras and produce the look they were after in camera. The shoot was easier because the DOP was more comfortable, the production was quicker and the ideas that were proving difficult with the digital cameras (extreme slow motion) was easy, as the same camera and stocks were used. The post production was also a simple affair which saved the production days, possibly even weeks. The final colour correction session was far simpler, remaining true to the original vision and the film transformed into a beautiful piece of work."
Manufacturers such as Kodak, Fuji and AGFA used to provide a considerable range of negatives, however sadly these are slowly getting eroded as the demand lessens. Fine grained emulsions give the best resolutions but are less sensitive to light. Therefore when you are shooting in a darker environment or where a vast depth of field is needed, a faster film should be used, however these are a lot more grainy which may not be the look that is wanted or preferred.
Faster emulsions will inherently be grainier. If using 16mm for blow up, slow or medium speed emulsions should be used, thus when enlarged to 35mm, the grain is not so noticeable. However this is still preference, some enthuse that the grain is what separates the look of film from digital.
Emulsions can be balanced for daylight shooting (5400K) or for stage acquisition under tungsten lights (3200K). If using tungsten stocks in daylight, it is recommended an orange filter is used and you introduce an increase in exposure: a blue filter would be required for daylight films under studio lighting. This is where your DOP is in his element, to be fair this is not my forte but hopefully you understand what I am aiming towards, these biases can in turn be eliminated by using filters at the point of capture.
The point is, all colour negative are developed in the same way and in theory can all be inter cut and edited together seamlessly. In truth there will always be image quality differences and colour biases, that is where the colourist/timer comes to the fore - to correct and iron out these 'bumps'. Hopefully within any project the cinematographer/DOP will undergo tests to select the best film stocks for any given situation throughout the shoot – lighting tests and makeup tests are vitally important to achieve the style they are craving – although I truly believe we are getting into the 'fix it in post’ mentality far too often.
Colour Reversal Film
This type of film produces a positive image with rich saturated colour's. They are suitable for telecine transfers but are not easy to duplicate from like negative originals. They also require a different developing process, not as simple as neg processing.
Print film has a much higher contrast ratio (gamma) than negative. Again a different process for developing is employed, brighter lamps and a different sequence of fixing, they give finer grained images.
These stocks in the DI is primararily what we are interested in, these are used for the final output negative from the recorder. They are used for making inter positives (IP) and duplicate negatives. They are preferred as they have a gamma of 1.0, which intrinsically means that it has a transfer ratio of 1 to 1, in essence the contrast is left unaltered (theoretically), in truth there is a slight loss. Printing from a negative gives a positive (inter pos - IP), then from an IP gives an inter negative (inter neg).
They also have low grain, it should be noted that when the scanning process records the image, it also captures the grain as well. You really would not want to put the image back to another grain filled stock, thus doubling the grain.
I am only going to mention black and white in passing, as a lot of black and white images are put back to colour film stocks within DI. You are at the labs mercy for this, if there is a colour bias in the soup on the developing process or print, you may end up with a slight hue, contaminating the true black and white.