8mm Forum: Another optical sound question ...

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Posted by Osi Osgood (Member # 424) on July 04, 2007, 10:41 PM:

I have another question for all us forum folks ...

Would anyone out there have a listing or knowledge of all the studio's that did super 8 optical prints?

I can think of three in particular, but perhaps someone out there would have a better grasp of the studios.

Actually, you would think any studio (super 8) could produce super 8, as the sountrack is printed right on the film and it doesn't need a lot of other processes.

Posted by John Whittle (Member # 22) on July 05, 2007, 08:29 AM:

quote:
Actually, you would think any studio (super 8) could produce super 8, as the sountrack is printed right on the film and it doesn't need a lot of other processes.

Actually it was very specific since the sound track was reduction printed from a 16mm negative as was the picture. Therefore a COR printer was necessary (COR = continious optical reduction) and it had to be balanced so that wow and flutter weren't introduced from the sprockets.

In this printer a negative runs on one track and the printer light passes thru it to a series of mirrors/prisms and reduction optics and either two or four prints are made on either 16mm or 35mm stock with super 8 perforations. In the case of 35mm, four prnits are made per pass and the stock has five rows of perforations. One row is slit off as the other four prints are slit from the 35mm stock.

This allows the lab to use their high speed 35mm positive processor to produce Super8 prints.

Super 8 optical sound required a second head on the printer with optics aligned for just the sound track and these were very expensive machines (over $200,000 back then) so were normally only found in the biggest labs (Technicolor, Deluxe, CFI, Rank, etc.)

John

Posted by Osi Osgood (Member # 424) on July 06, 2007, 09:55 AM:

Thanks John! Good info.

If you have any other info about optical sound super 8mm please by all means, pour forth!

Posted by John Whittle (Member # 22) on July 06, 2007, 01:34 PM:

quote:
optical sound super 8mm please by all means, pour forth!

Optical sound on Super8 was first proposed by Technicolor and they made the first projector which used their sealed cartridges. The market was for educational films and the maximum cart I think was 400 feet. Since the films were i endless loops in the carts, they were often scrached and degraded and the more they were used the dirtier the prints became.

Technicolor had printed 16mm prints two up in a 35/16 format (which is two prints side by side going from head to tails). The other labs printed 16mm as 35/32 where the 16mm prints were up and back like on a regular 8mm camera where you turn the film over. The advantage was normal 16mm negatives and sound tracks could be used whereas in the Technicolor method, they made a special 16mm double rank negative and a special sound track and you had to order prints in multiples of two. (MGM Metrocolor as printed 35/16).

So when Technicolor did super8 optical sound, they did two things.
1. The picture was REDUCTION printed from a 16mm negative and
2. The sound was REDUCTION printed from a 16mm negative as well.

Special printers were made that had the opticals and it was a slit-scan process (not a shutter step printer method) of reduction printing.

The other problem was the sound track. In 16mm color positive prints, the track is printed from a black and white negative and a #12 filter (yellow) is used to limit the exposure to the top two layers of the print stock for maximum sharpness. Then in developing a developer is applied to the sound track to provide a dye+silver track. The IR which the photocell sees and converts to an electrical signal is not blocked very well by the dyes alone in the print and so the silver brings the quality back to that of a black and white print. The lack of silver in the sound track was one of the problems that Cinecolor and other early color processes had (including Technicolor Blue track). The Technicolor IB process photographically printed the sound track and developed a black and white track and then applied the color in the IB process so a Technicolor print had excellent sound. Eastman Color and other color positive processes used this application of a developer.

Well with Super8 this posed a major problem. The track was very narrow, an overlap of applicator shows as a yellow brown stain in the picture and applying the developer to either 16mm or 35mm multirank prints was difficult if not impossible on a production basis.

The solution was proved by Agfa (and their Super8 stock was widely used for optical sound because of this). The Cyan dye in the Agfa stock (besides being more stable than the Kodak dye) blocked light more into the IR than the Kodak stock and thus a Super8 Optical sound print could be produced without application.

So a word of warning about optical sound, if you find a print on Kodak material and the picture has faded to pink, chances are the sound will be very very weak if not almost impossible to hear as well.

I don't know of any lab that actually applicated Super8 prints, but it's possible some did. I think the Agfa stock was introduced in 1970 or thereabouts---at least I recall it as a topic at a 1970 SMPTE Conference in Los Angeles.

John

Posted by Martyn Stevens (Member # 861) on July 06, 2007, 02:09 PM:

There was a standard 8 optical sound system that never quite made it into the market, tho there was a projector by Toei for it. I gather it involved some reduction of the picture area, as with 9.5. More generally, it has always been my impression that optical sound tracks are usually printed in a separate run, not at the same time as the picture. Has anyone tried using an LED for an exciter lamp?

Martyn Stevens

Posted by Kevin Faulkner (Member # 6) on July 06, 2007, 04:06 PM:

John, Thats really intersting info which I was unaware of.

One thing I will say is that most of the airline prints are on Kodak stock. The earlier now fading are on Eastman and the latter are on LPP. I don't think I have ever see any Agfa airline prints. The Kodak stock was thinner which is why I think they used the thinner Kodak so they could get the running time into the cartridges.

Kev.

Posted by Osi Osgood (Member # 424) on July 06, 2007, 07:15 PM:

More great info, thanks mates!!

It's true! There was standard 8mm optical sound films, as I ran into a print of "Futureworld" (feature film) as a standard 8mm optical sound release. I kick myself for not buying it, if for no other reason than to just see how sharp the image may have been, as I have found the optical super 8 prints to be exceedingly sharp. It may have been the sharpest
standard 8mm ever made, (though I have found some incredibly good Blackhawk standard 8mm prints.

Posted by Osi Osgood (Member # 424) on July 06, 2007, 10:53 PM:

If I may add an additional comment concerning film stocks, what Kevin stated about the film stocks is largely true, but i feel that there must have been some additional film stocks, as I have found that the early 70's film stocks must have been at least a higher grade of Eastman or another stock.

Perhaps it was a late "Kodak" stock that was dis-continued in the mid 70's or so, as i have found that many a Derann print from the 70's that has faded, but little real colour loss.

If Agfa or Fuji was used, I haven't seen it, but then again, the way optical sound film is printed, (much of it having black in the sprocket area, which is, of course, where film stock numbers are located), we may never know.

Posted by John Whittle (Member # 22) on July 07, 2007, 12:12 AM:

quote:
There was a standard 8 optical sound system that never quite made it into the market, tho there was a projector by Toei for it.

I remember the Toei Projector, think I had a flyer from their US distributor. Don't know of any US lab that produced at prints for it (It pre-dated super8 by a year or so). Considering the tube amps and film speed and print films of the late 1960s, it would have been difficult to make prints.

Color prints are made from two negatives, a color negative for the picture and a black and white negative for the sound track. Variable area tracks are a bit tricky since they require a balance of the negative exposure and the print exposure to cancel fill in from the printing process. Exposure is set with a cross-modualtion test where two tones are recorded on the negative and as the exposures are varied one or the other tone is heard. When they're balanced, the exposure is correct.

To use an LED in place of the exciter lamp would require a re-design of the small gauge sound scanners since this would require a reverse scan sound head. In 16mm and Super 8 projectors, the filament of the lamp is reduced and focused as the slit on the film (a scope type optic is employed to narrow the line). The narrower the slit, the higher frequency can be reproduced combined with film speed. Of course there is a trade off if it gets too narrow you pick up noise and volume drops off.

Reverse scan sound heads are popular in 35mm projectors and actually date all the way back to 1929. The Western Electric push pull reproducer was a reverse scan device with a dual phototube pick up. Everything was there in the reproducer to do stereo optical in 1929!

John

Posted by Paul Adsett (Member # 25) on July 07, 2007, 02:09 PM:

John, your technical knowledge and expertise of film systems is amazing, and we are all very lucky to have you as a member of this forum.

Posted by Osi Osgood (Member # 424) on July 07, 2007, 05:29 PM:

I was just thinking that myself, Paul. Great info John!

Posted by Martyn Stevens (Member # 861) on July 10, 2007, 11:26 AM:

John,
Thanks for comment on LED as exciter. I don't really know enough to fully understand, but let me try this question. On the Pathe Vox/Super Vox, the scanning beam is produced by an adjustable slit in the sound telescope - I have adjusted these to get better "top". Would an LED work for this set-up?

Martyn Stevens

Posted by John Whittle (Member # 22) on July 10, 2007, 03:22 PM:

quote:
Thanks for comment on LED as exciter. I don't really know enough to fully understand, but let me try this question. On the Pathe Vox/Super Vox, the scanning beam is produced by an adjustable slit in the sound telescope - I have adjusted these to get better "top". Would an LED work for this set-up?

Without a diagram, here's how you use an led as an exciter lamp. Instead of having a lens between the light source and the film, you bathe the film in the light and then the lens is on the reverse side with a slit, the light that goes thru then falls on the photocell/phototube.

The problem in the small gauges is this set-up requires more room. It's easy in 35mm with all the space around the sound head, but in 16mm and Super8 with the tighter advance (7.2 inches n 16mm vs 16 inches in 35mm) getting all the pieces in place is difficult. It's not impossible and those few 16mm projectors that used the projection lamp to illuminate the sound track (The Calvin Movie-Mite and I think the Natco) are examples of the reverse scan.

If you've got a Movie-mite, take a look at the way it's set up and see if you can adapt the theory to the Pathe.

John

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