The world of non-commercial film and A-V
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Journey: part twenty-two
This article is really Bill Rahmann’s work. Bill modified the projectors and made the special equipment that set the systems up. I worked with Bill on transferring the cine film to DVD and made notes to the best of my ability. Bill then added the technical information and other advice. All this provided a reliable system that works every time. - Arthur Bullock
|In very expensive labs cine film can be scanned frame-by-frame
to make a top-quality electronic copy of the pictures. That
approach is not practical for amateurs, but very good copies can
be made by other means.
The main problem is that PAL video works with 25 pictures per second and NTSC video at 29.97 pictures per second, whereas amateur film was shot at various speeds. In the earliest days cameras were hand-cranked, the first clockwork motors could be variable so speeds were not always consistent. Things improved when electric motors were introduced to cine cameras.
|9.5mm film and Standard 8mm mainly ran at 16fps (frames per
second). Super-8mm mainly ran at 18fps. Some Super-8mm and most
16mm ran at 24fps. This means some compromises have to be made
when transferring from film to video.
In 9.5mm and early Agfa 8mm it was possible to put a notch in the film when a caption was shot. Projectors held any notched frame steady for 10 seconds before going on. That saved film but gives us transfer problems.
theory it is possible to transfer picture and sound together, but
in practice it is much easier to transfer them separately. For our
purposes the aim is to get both picture and sound into our
computer editing programs where we can adjust speeds, "hold"
frames, tweak brightness, contrast, colour and so on as necessary.
This article assumes we will record the pictures onto video in our camcorder and later transfer them to computer.
It is possible with most cameras to connect them directly to computer with a Firewire cable and thus record the images into computer immediately. In practice this usually adds complications. Unless you plan to transfer a great deal of film to video it is simpler to record to camera and then transfer to computer, even if this adds a bit to the turnaround time.
Shoot video of the picture on a screen
This is the usual system that amateurs use. Part 21 - Transferring Cine Film to DVD describes this system in detail.
Don Chapman and I used this system. On several occasions we copied the film to a video camera digital tape in one pass with what I can call perfect results. Most of them, however, required several passes and a lot of editing in a computer. We had expert advice from Nev Long and Alan Beale, but there was a lot to learn.
Bill Rahmman found someone in Melbourne who repairs 16 mm Projectors - Bill’s 16 mm projector now works perfectly. A tip from Alan Beale prompted Bill to mark a black framed rectangle on a white screen. I could now easily aim and correctly zoom my video camera to the required position.
Bill is a gadget man, so we can now easily control the projector speed and as his 16 mm projector is in good condition, we are now copying 16 mm film onto the video camera tapes, every time in one pass.
The stroboscope that is used to check the projector speed has a bright LED which is the best light to use, as it only flashes on positive half cycles. For 16 2/3 fps (frames-per-second) you then need 3 black bars on the strobe. For 25fps you need 2 black bars. If you use a neon lamp instead of an LED it gives 100 flashes per second so you would need 6 and 4 black bars respectively.
[Ed: this assumes you are working with PAL video and an electrical power supply with a frequency of 50 Herz (50 cycles per second) such as is supplied in Australia and the United Kingdom. NTSC video runs at just under 30fps and in many countries the mains power is at 60 Herz. You will need different strobe lines to suit the situation in your country.]
You need a film projector in good condition - and you need an effective means that will adjust the projector speed to 16 2/3 frames-per-second for a three-bladed shutter or to 25 frames-per-second for a two-bladed shutter.
Controlling the Projector Speed
|(a)||A blue filter was held in front of the video camera lens - this adjusted the reds perfectly.|
|(b)||The video camera White Balance was set to Internal Lighting (Tungsten} - this adjusted the reds perfectly.|
|(c)||The video camera was White Balanced on the projector screen without a film in the projector gate - this gave a pure white on the monitor, so this will work satisfactorily.|
|(d)||While the video camera was White Balanced on the projector screen, without a film in the gate - I then set the Auto Exposure to Spotlight, so as to get a slightly darker picture, this made the reds too bright - using the Spotlight setting was not a good idea.|
Because of technical limitations most home movie soundtracks were quite simple. Often they consisted of a piece of music with some commentary spoken over it. You might choose to replace the original sound with much higher quality modern recordings of the music and words. One enthusiast replaced the voices of his children in a family drama film with the voices of his grandchildren speaking the same lines. More often you will be copying the film for archival and sentimental reasons, so you will want the original sound. ("That's what granny sounded like when she was young.")
It is usually better to copy the soundtrack separately. All modern video editing programs make it easy to match up a separate sound recording with the pictures later.
Do NOT try to copy the sound directly into your video camera. If the camcorder has a sound input socket at all - many don't - it will be intended for microphones. Microphones use tiny electrical signals. Any sound output you get from a projector or tape-player will be much too high and could seriously damage your camera.
Quite often cine film makers created their soundtracks on reel-to-reel tape or cassettes which were played as the film ran, or were transferred onto the film. If you have access to those tapes and a suitable playback machine, you can copy the sound from them rather than the film. Be careful to connect the "line output" of the tape player to the "line input" of your computer and NOT to its "mic input". (If the sockets are colour-coded the "line input" is usually light blue on a PC but check.)
Part 21- Impedance of line level audio and microphone level audio shows how an Audio Mixer can be used to automatically adjust the volume of line level audio down to the weak signal that can be fed into a video camera, It will also automatically adjust microphone level up to line level volume.
If you only have the film's sound to work with, try to get a projector with a "line output" socket. (These were often fitted so that sound could be plugged into a separate amplifier for shows in a big room.) Plug a suitable cable into the "line output" and connect the other end to your computer's "line input" socket. Be careful NOT to plug it into the computer's "mic input" socket.
Usually the volume from a "line output" socket does not
alter when you adjust the volume on the projector. Your
adjustment must be done on the computer.
See Part 21 - The Process shows a diagram complete with instructions on how to reduce the volume of the line level audio so it can be fed into a video camera microphone socket.
On the computer put the line-input slider very low and raise it gradually. Listen to what comes out through your computer's speakers. Your aim is to have the loudest sound on the film come across clearly without distortion.
If the projector only has an output socket for a loudspeaker be very careful. The safest option is to buy a gadget that feeds the sound from there onto your computer through a USB port. (e.g. Griffin Technology iMic USB Audio Interface £32.95 in January 2010 from amazon.co.uk) If you are only transferring a couple of films and don't want to spend that much, plug a loudspeaker in using a lead that lets you put the projector into the next room. Set up your camcorder running near the speaker and run the film with the volume at a comfortable level. Transfer the sound from that "video take".
Beware of Phase Cancellation. Speakers should not be placed close to corners of a room. There was a time when I shot a movie with the mic held up between overhead floor joists - I got a truck-load of phase cancellation from reflected sound off the sides of the joists.
Keep in mind that home movies did not have high-fidelity sound. Once your have the soundtrack in your computer you can often "clean it up" with careful use of the sound filters in your video editor.
WARNING: Audio signals from the output sockets of a projector, tape recorder, VCR, TV etc. are very high when compared to signals from a low impedance microphone, which has a very low signal. So, if you accidentally feed “line level audio” into a low impedance microphone socket you will blow something up: either your own ears or your equipment.
The audio signals from all the movie projectors that I have seen so far are line level.
This is the system the gadget men set up.
The picture shows a 16 mm film projector with the lamp house removed. The video camera is fixed in a wood frame, upside down. It is aimed through a magnifying lens onto the gate. A weak back-light is aimed back through the projector lens onto the gate. We don't need the projector lens, it is just convenient to have it there. This back light shines onto a piece of opal glass or a piece of tracing paper (detail paper might be better, it is slightly more opaque and is more flexible) so as to evenly disperse the light. The blue filter is also attached at this point. The automatic white balance on cameras doesn't work properly in this situation. You could fiddle with the video camera's manual white balance to get the same effect. There is a stroboscope attached to check the projector speed and a variable resister is also attached so as to adjust the electricity supply. The setting is very stable, one man can easily do this job. The oscillator is adjusted on this projector, on others it may be a governor to be adjusted or the fixing of a variable resister on the power supply.
The Bell and Howell 16 mm film projector has a DC motor where the speed is locked electronically to the frequency of an oscillator (an oscillator simply produces an alternating voltage at a particular frequency. On the projector there are two preset controls for sound (24 fps) speed and silent ppeed (18 fps). If you know how, you can have an external control that supersedes these presets, and you can vary the oscillator frequency over a continuous range. Thus the projector motor speed will vary to match (eg.,10 fps to 30 fps).
Now the picture on the DVD is very good. The colour is good because of the blue filter and there are no visible problems as the movie is being played.
There is, however, a hidden fault - luckily one that can be ignored. You cannot see this fault while the movie Is being played. The defect shows every third frame. Look for an arm swinging. You will see that every third frame shows a cross fade from an adjacent frame. This third frame shows a bright clear image, but superimposed on it is a half faded image of the next movement. It is impossible to see it as the movie is played -- we see a smooth flow of motion. The “persistence of vision" property of the human eye (the same property that makes movies and video possible) fuses the images with a moving image.
When transferring films that are dramas, the audio speed may be altered too much. You may then have to snip out parts of the audio or parts of the picture to restore lip sync. There are video editing systems that will speed-up or slow-down video pictures, slightly if required so as to restore lip-sync. Ideally you want a system which will change the length of the audio track without changing the pitch of the sound as it does so. Adobe Premiere does this. Some stand-alone sound programs can also change speed but maintain pitch.
Bill has Ulead Video Studio 8 software. He has checked it and finds that it will lengthen or shorten the video. Corel Video Studio Pro X2, which is the upgrade of Ulead will also adjust the length of the video. Use the 30 day free trial to check if it suits you.
The equipment set up is similar to the 16 mm equipment except that the projector is upside down and the video camera is the right way up. (The old Bell and Howell 8 mm projector made this simple.) The main problem with 8 mm film projectors is that the lighter motors do not have a very stable speed. Bill is working on this. This set up has a synchronous motor - it locks to the electricity cycles. The motor has a specially made pulley with a diameter such that it runs slightly faster than the required speed. That pulley has a second pulley attached to it which has a leather shoe lace rubbing on a part turn around it. Tension is pulled on the leather strip by a screw, so as to brake the motor to the required speed. It works!
Bill has now removed the leather shoe lace - we now use a Variac (a Variable Voltage Transformer) to adjust the speed of the projector - 240 volts reduced to 170 volts got the speed exactly correct. We could now stand back without our hand on the control, it was as steady as a rock, it only needed an occasional very slight adjustment.
This equipment should only be made by a competent gadget person because there are dangerously high electricity voltages involved.
The splices on Standard 8mm film produce a knocking noise on the video. You have to use the audio from the original audio cassettes or reel-to-reel tape if available. Fortunately the old film makers tend to keep those cassettes. If that is not possible your must go through the soundtrack in your editing program and cut out each separate "knock". The splices on Super 8 and 16 mm do not produce this knocking noise.
Handy hint: The rubber bands used in many parts of projector drives often perish and break. You may also want to make new belts for this sort of lash-up. To make a new rubber belt, get 'o' ring material sold by the metre and Loctite 406 glue from a bearing supplier. This glue is stronger and more durable than superglue. Trim the 'o' ring to length, and glue the ends of the 'o' ring together.
Once stored in the computer's editing system it is possible to make changes to the pictures. As always the aim should be to capture the images as well as you can because tweaking in the computer never works quite so well. The trick is to work shot by shot and to make very small adjustments each time until you get close to the ideal.
Using the Brightness and Contrast controls is the key to adjusting the exposure. Adjust the brightness first, then the contrast, then adjust the colour (saturation) to suit. On my Mac system I have found the image adjustment tools for photographs to be excellent, but not the ones for video. You need to experiment with the tools and filters available on your editing system ... but remember to save safety versions of the original transfers in case your adjustments do more harm than good!
Silent projectors usually had a series-wound AC/DC motor with a simple
speed control (Series Variable Resistor). They didn’t keep very good
speed, as this was not needed for picture only. When magnetic stripe and
sound arrived, speed had to be controlled a bit better:
© copyright Arthur Bullock, 2010