Right through the '60s, '70s and '80s, right up till about 1990, duplicating – making inter... interpositives and internegatives from the original negative – was not a very good process. You... you could see the difference with a print made from the original negative and a print made from the dupe. There was quite a deterioration in quality and it wasn't until about the '90s that Kodak brought out duplicating stocks that... that more or less eliminated the difference in quality. And what would happen with the older type of duplicating stocks is that you would... you'd get a deterioration in quality, in... in definition, and the contrast would go up, so that if you had a scene which was going to dissolve, there would be a jump where the dissolve started and until the dissolve ended, and then you would go back to the original quality. So this... this could be quite distracting, and a way of getting over that was to do what was known as A and B printing, which avoided having an optical, which meant that... that when you... when you printed in the lab you had what was called A and B rolls, and roll A would go through the printer and fade out, and then roll B would be printed and fade in, so that you were actually still using the original negative. And this... this was used quite... quite a lot by Ken Russell, both in Billion Dollar Brain and Women in Love. So we... we stayed with the original negative quality and we didn't have any opticals, which... which mean... meant going to a dupe neg.

So in those days we tried, when we were... came to the final post-production, and the grading of the picture, which of course is very much the... the cinematographer's responsibility, and the editor's always there of course, and the director is usually there but not always, and sometimes the producer. But I think it's the cinematographer that has the primary responsibility for... for grading a... a picture because you know what you've put into the negative, you know what your original intentions were and you know the colour filters you've used and how to sort of match things so that you... you get rid of the changes perhaps in light. When you're shooting on exteriors you always get certain discrepancies when you're shooting over a period of time. These were all ironed out in the grading process. Well, of course, this used to be done, in those days, at the laboratory where the colour grader or a timer, as the Americans call him, would make a print using the cutting copy as a guide and you'd see this first answer print and view it together, and make comments and adjustments, and go away for a couple of days while the grader altered things and altered his printer lights and his densities and so on, and then you'd look at another print. And this, depending on the complexity of the film, could go on for up to about five or six prints. Well of course every time that the negative was going through the printer, it... it was at risk. There was no protection and you've got millions of dollars worth of... of precious film going through the printer where it's... there's always a possibility that there might be a break or a scratch, and a damage and so on, and... and so it was a high risk business. Well of course, that's been eliminated now because most... most post-production is done on... on a digital process where they... they transfer the negative to digital and you... you edit it digitally and colourise it digitally, and do all the grading with a colouriser rather than a film grader, who can make infinitely more adjustments in terms of... of colour, density and even... and contrast, you see; using the old method we couldn't alter the contrast really. But nowadays, if... if you've got a shot that's a little flat, then the colouriser can tweak a little bit more contrast into it, so that it matches the shots that go either side. And this technology is constantly improving.

I... I was at an equipment show last weekend and Joe Dunton has got this equipment... this monitor known as a Lustre... Lustre is the name of the process, and it's able to give you up to 4K quality, whereas previous... machines could only go up to 2K, which means that it's got it very close to the... the quality of film and the texture of film, and the detail in film it’s.... Digitally it's now very close, so that the practice nowadays is... is not to do all this timing in the lab, but 20, 30 years ago that was the way we had to do it. And so when a film came up for release you would try to make as many prints as you dared from the original negative, perhaps six or eight, to... to play in New York, Los Angeles, London, Rome and Paris, where the film was going to be previewed and where you would have, you know, your  critics and so-on, to present the film in its best light and then the release prints were... were all made from the dupe negative, and until recent years were inferior.