Oct 122011

A few months ago, I decided to try to digitize my family’s home movies. They’re all on a couple of eight-inch (400-foot) film reels, and a couple of other small reels that were left out of the main opus.

It should be easy, right? After all, 8mm film is not a difficult thing to understand. It’s made up of little frames that you can actually see. All that’s needed is a way to turn those images into digital ones, and drop them into a computer. Then, with the right software, you can make corrections – take the blue skin tones out of those dark scenes, or remove the yellow cast on old film.

The easy way

The quickest and easiest way to digitize cine film is to project the films onto a screen, and videotape the picture. I’ve read in a few places that you might get some flickering if the film image doesn’t quite mesh with the video image, but I have never found this. For the best and brightest reproduction, don’t bother pulling the full-size screen out of the musty closet; instead, project the images at close range onto a sheet of smooth white paper – the bright white paper used for printing photographs on an inkjet printer is particularly good. Stick the paper to a wall, put your video camera next to the projector, and line up the camera on the same image, and you should get a very bright, colourful picture. There’ll be some minor distortion caused by the difference in angle between the projector and the camera. You can reduce this by putting both the projector and the camera as close together as possible, but at the same slight angle to the paper, one to the left, one to the right. The wall image will be slightly enlarged on one side, but the camera’s view should compensate. On a modern TV screen, many of which are a similar size to a projector screen, the final result should look very good – much more colourful than a live viewing of a projected film, but with the same distinctive look and feel of “movie night”.

The problems with projectors

I didn’t want to use a projector this time, though. Projectors cause some problems of their own. Even a well maintained projector causes some wear to film, and a projector that is in “vintage” shape can be rough on film. Projector lights are hot enough to melt the film if they jam. Sprockets can put holes where you didn’t really want them. That didn’t matter so much years ago, when the film was just a few years old – you just splice out the ruined part and project it again – but now, when the the age of most family films is measured in decades, you probably don’t want to see sections destroyed. If you have valuable old film, you are taking a chance each time you run it through the projector.

I didn’t think it was worth the risk to try a projector approach – especially since the image that comes out of the projector isn’t actually that great. The projector doesn’t show the whole frame – most projectors crop the edges. With standard 8mm film, the cropping can be significant – perhaps 20% of the picture. Also, the image from most projectors is unevenly lit – it’s brighter in the centre than it is at the edges. Projector lenses introduce more distortion, making the image softer than it could be. The registration of the film isn’t great either – the projector lines up the frames using the sprocket holes on the film, but these are not exact, and the film moves up and down slightly between frames.

I wanted to digitize the film using the highest possible quality – copy it so that all the information on the film – everything that makes up the actual picture – is reproduced.

The hard way

There are two ways to digitize film without projecting it. You can scan it on a scanner (it must be capable of scanning transparencies, such as photo slides), or you can photograph it with a camera. In both cases, you need equipment that can accurately reproduce the tiny details of a film frame – the picture is only 4.5 mm wide. But the really hard part is doing the same thing for every frame in the film – around 960-frames for each minute of film. Even a small, 50-foot reel will involve thousands of scans or photos. Instead of digitizing your films in minutes, it will take you hours, or days, or weeks.

Is it worth it? I think so, but my life is a series of small obsessions.

I experimented with a number of methods, using both a flatbed scanners (Epson V500 Phot0) and a transparency scanner (an older Minolta Dimage Scan Dual III). Using the transparency scanner involved disassembling it and threading the film through it. Both scanners produce images that were passable, but slightly unfocused.

A much better method is to use a digital camera with a macro lens. A good quality DSLR camera and macro lens will cost you around $2000, but you can get excellent results with a point-and-shoot camera and some old camera lenses for much less. The trick is to install a regular camera lens from an old SLR, attached backwards onto the digital camera. I used a Canon A630, with a $10 macro lens adaptor, and an old Canon 50 mm lens. This gives enough magnification to get a very clear view of each film frame. A similar arrangement is also a fast way of photographing slides.

The camera needs to be held at a precise distance from the film. I bought two focusing rails from eBay (FotoMate, about $13 each, with free shipping), one to control distance from the film, and one to control the horizontal position.

The film was lit from behind by an LED vanity light – the kind that might be used in bathrooms. Although it’s not as bright as a projector bulb, it also won’t burn the film. In fact, it’s cool to the touch. The diffusion on the bulb is excellent, and, positioned about an inch behind the film, gave smooth, even lighting.

I set set the camera to an automatic shutter speed, and some speeds were quite slow, so it’s important to have everything stable. I used CHDK (Canon Hack Development Kit) to control the camera. This allowed me to add an external shutter release, so the camera wouldn’t shake when I took each photo. My external shutter release was actually an old Morse key, wired into the camera’s USB connector. (Some cameras will allow this trick, and making a shutter release is fairly easy. I found instructions online.)

The film is photographed frame by frame, and the camera numbers the frames automatically. After the memory card is filled up, I dumped the data onto the computer. Later, I renumbered all frames sequentially, and they can then be imported into a video program as a JPEG sequence. The film was shot at 16 fps. I halved the speed (duplicating each frame) to reproduce it at 32 fps, which looks good, and avoids any interpolation or blended frames generated by the computer.



 Posted by at 12:01 pm