Film-Tech Forum ARCHIVE: aperture plates and silent films

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Posted by Scott Norwood (Member # 30) on 09-27-2005, 07:41 PM:

It seems that I will be cutting plates this week for a full-aperture silent frame, which I have never done before. Is there a standard for this (or, better yet, a test film)? I have RP-40 and a Super-35 test loop, which (in theory) should give me what I need to get the approximate height and width, but is there something better?

I was planning on starting with undercut scope plates (this is for Simplex PR-1014s; I have extra new scope plates lying around adn I don't think Strong sells full-frame silent undercut plates, anyway),unless there is an easier way to do this. My intention is to use the backup scope lenses and realign the lamps as necessary to get even illumination.

Posted by Louis Bornwasser (Member # 3063) on 09-27-2005, 08:18 PM:

1. You will find your ppicture too small with scope backups. The scope height is higher than the silent. Of course the wide will be back to 1.33/1.37.

2. Remember the center of silent is center of film, not center of RP-40. Reaiming the projector is half the battle; the rest being lamp alignment.

3. Generally silent is considerably slower than 24 fps by a variable amount determined by the speed that the camera man happened to use. Good Luck!! Louis

Posted by Mathew Molloy (Member # 666) on 09-28-2005, 01:04 AM:

Scott - I have some loops for full frame here at the theatre. I think they're specifically for focusing but it's what we used for filing our plates for that ratio. Send me an email and I'll get it out to you.

Posted by Leo Enticknap (Member # 534) on 09-28-2005, 02:03 AM:

The way I used to do it was to cut three sides with the RP-40 running normally and then turn it round, so that you've got an edge to cut on for what would be the 'wrong' side for sound.

As Louis points out, realigning the optical centre of the picture is as big an issue as cutting the plates. As far as the lens goes, you can use a tapered offset barrel to fit a 62.5mm lens into 70.6mm holder at a slight angle: if your theatre is going to be showing silents regularly that's probably the best option, as it enables you to swap lenses with your other ones quickly and easily. The other option is to physically shift the projector slightly, which is obviously only possible if the pedestal or console isn't bolted to the floor. Again, as Louis notes, the lenses will probably want to be one or two mm shorter than for 'scope, as most silent apertures (and early sound ratio ones, for that matter) have significantly thicker frame lines. They do vary widely from film to film, though, as different cameras and step printers had very different apertures in those days. But if your budget doesn't extend to dedicated lenses for silent shows, the 'scope backing lenses will just about do if they can be separated from their anamorphs.

If your theatre doesn't show Academy or silent on a regular basis, you might also find that the masking won't come in far enough to properly mask the picture; especially if it's a system which only has two presets.

As for the speed, there are varying rules of thumb. By the 1920s, most Hollywood and European studios issued cue sheets to theatres stating what the intended projection speed for a given film is, which is not always the same as the shooting speed. Sometimes a director wanted a film shown slightly slower or faster than the shooting speed as a deliberate visual effect. In the post-WWI period projection speeds increased significantly, prompted by a rise in the number of projectors with two-blade shutters, which in turn was caused by the need to maximise light output in the newly built 'picture palaces' with very long throws. When 24fps was eventually standardised for sound (before then, there had been no need to standardise shooting and projection speeds, as it needed a very big discrepancy for a picture to 'look wrong', where as the change in sound pitch is very noticeable), it was more a case of locking in existing practice rather than imposing a new one. As a sidenote, some of the early optical systems didn't use 24, though: De Forest Phonofilms ran at 20, while the first version of RCA Photophone ran at 22. Going back to the teens and earlier, shooting and projection speeds were generally a lot slower (for example, some shots in The Birth of a Nation were cranked as slowly as 12fps, and this film shouldn't be shown faster than 16).

With speeds and shutters, what you can get away with varies from projector to projector, and I'm not familiar with model of Simplex Scott mentions. For example, on an FP-20 you can get away with going down to around 20 without a significant flicker, whereas on the Vic 5 anything slower than 24 really needs a three-blade shutter. If you do fit a three-blade shutter, more light will be needed. If your lamp has some reserve power (i.e. it can be cranked up by 10-20 amps for the odd show without any significant risk of damage) that's not a problem, but if you're running at the limit of what the lamp and/or rectifier can deliver, that could be a problem. When spec-ing a booth which will run silent shows from scratch, the reserve power should be factored in, so that the lamp power can be temporarily boosted when the three-blade shutter is in use (either that or leave the three-blade shutter installed permanently).

If you can give me the title(s) of the films you'll be showing, I can ask around a few archives and try and find out what the speed for them is supposed to be, if that's any help.

Posted by Pete Naples (Member # 761) on 09-28-2005, 02:21 AM:

Can't add much to what Leo has said about lenses, shutters etc. However for a nice easy way to find the optical centre, look at your RP40. See where it says SMPTE in the middle, in big letters? The true optical centre lies between the T and the E. Much less fiddling than turning it round.

Posted by Gilbert Travin (Member # 2138) on 09-28-2005, 04:29 AM:

Hi !

With a DP70 (Norelco AA II [Big Grin]

), no problem of centering : you put your silent-film lens on "70 mm" position !

Posted by Steve Guttag (Member # 268) on 09-28-2005, 06:32 AM:

I've equipped many a screening room/theatre for silent film presentations.

The silent aperture varied much before WW1 but it did seem to standardize to around 680 x 910. A friend of mine has a rather extensive collection of early 20th century projection and sound equipment (as well as films). One thing he let me do was go through several projectors, including Powers and early Simplexes and such...the kind that had apertures, not aperture plates for there was just the one in those days...all were hand cranked machines.

Using calipers, I came to the .680 x 910, figure, regardless of manufacturer of projector and within a couple of thousands on either dimension.

In practice, you will generally find that you have more slop on the height of the frame. As most silents will project just fine up to .715. I have one customer that, for some shows, wants to see just about everything, including the edge of the camera aperture...I call it "Super-Silent"...those plates are cut as wide as .945" wide and I think .725" tall.

Whereas your scope lens provides for .690", trust me in that you won't have any problem showing the .680" silent pictures. For the sides, a poor mans silent test loop is a 35-PA or CLT-2000 spliced such that emultion switches to base at the splice...height will remain the same, but you will be able to center...note the focus will shift slightly when it switches to base-to-the-lamp but you only need it to center things up. Another choice is to get your hands on some Super-35 target film that will et you determine where .910 is. Another option is to get you hands on some 35-AT (RP110, I think) that is not offset for optical sound (as it was for a great portion of its life).

If you have Simplex XL's or 35s (non-turret). The easiest way to compensate for the image shift is to purchase the Simplex 35/70 upper lens guide as it will allow you to rock the lens holder between film center and optical film center. They are not too pricey and once done, you can shift the lenses for all formats to precisely center all images.

As for aperture plates...you might be able to lay your hands on a CinemaScope 2.55:1 precut or undersize...they are .715x.910...a bit tall in height but most silents will play just fine with it. However, you can start with most any plate since they are all the same blank with a different sized hole punched to start you off.

Posted by John Pytlak (Member # 331) on 09-28-2005, 08:08 AM:

The first SMPE "standard" for the image area of silent 35mm release prints was published in 1917. The image area specified was 0.906 x 0.6795 inches (29/32 x 87/128 inches), centered on the film centerline.

Posted by Frank Angel (Member # 248) on 09-28-2005, 08:34 AM:

I know that the lamphouse optical alignement would theoretically need some readjustment with the wider aperture, but we do silent all the time and don't really find that there is any significant light fall-off using the silent as opposed to the scope plates and the xetron lamphouse. With our Peerless carbon arc lamphouse that allows for very easy horizontal and vertical reflector adjustment (how sweet those adjustment knobs on the back of the lamphouse), a slight twist of the horizontal adj knob and you're good to go.

Posted by Scott Norwood (Member # 30) on 10-03-2005, 10:10 PM:

Thanks for all the suggestions; the "RP-40 mobius strip" idea worked out great. Amazingly, I even had the correct lenses in my collection and didn't need the scope backup lenses after all. I did need to slightly de-focus the lamps (Super Lume-Xes) for silent, but didn't see the need to re-align the reflectors.

I hate cutting plates, but this was actually one of my better experiences with them.