Film-Tech Forum ARCHIVE: Apeture plates

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Posted by Eric Womack (Member # 4458) on 07-10-2008, 05:23 PM:

I have to file a set of plates for a Silent movie we are running and I am looking for any hints and ideas on a faster less time consuming way of filing these. Any ideas? these are for a Simplex XL. Yes before anyone asks the picture does indeed extend into the sound track area of the film stock. thanks for any ideas or suggestions ahead of time.

Posted by Bill Carter (Member # 156) on 07-10-2008, 07:14 PM:

Normally, you'd be using RP-40 test film to file a plate.

Cut the inboard (non-soundtrack) edge of the plate as usual, using the RP-40 as your guide, the flip the RP-40 backwards in the projector, and file the outboard side to the same markings.

Remember, of course, that the full aperture silent image will then be off-center on your screen. You'll either have to recenter the machine, or live with the off-center image (and fix the masking to accomodate it).

Posted by Eric Womack (Member # 4458) on 07-10-2008, 08:15 PM:

Thanks Bill. This stuff seems like a lost art?

Posted by Scott Norwood (Member # 30) on 07-10-2008, 10:31 PM:

Start with scope plates. That way, you only really need to file out the soundtrack edge.

If you have side masking (common height), the scope backup lens will usually be correct for silent prints (or at least reasonably close--nothing was really standardized at that time).

Remember that you may need variable speed capability if the film is earlier than the mid-1920s and hasn't been step-printed.

Posted by John Hawkinson (Member # 1135) on 07-11-2008, 12:37 AM:

When you say faster, it might be helpful to know "faster than what." Various tricks include:

Splicing a half-twist into the RP40 so it flips between the left edge and the right edge every cycle.
Using a "nibbler" (a metal-cutting tool that punches out small rectangles of metal) to remove a lot of material quickly.
Using a dremel tool for rapid metal removal. As with the nibbler, you trade speed for accuracy, so don't get too close! Go back to a file to finish it.
Using a digital caliper to figure out exactly how far you need to go and how far you have gone. WARNING: Basically everyone on Film-Tech seems to disagree with me that this is at all useful. I find it useful, but I think it falls under "use what you know." Again, though, don't get too close. The size of the aperture on the screen tends to appear larger than the measurable size of the whole by a few thousands of inch, in part because of shadow and edge effects, the aperture being out of the focal plane of the lens, and some lens effects.
Using a "safe" file to finish the corners. Such a file has smooth non-cutting edge at 90 degrees to a cutting edge, such that you can work on one side of a corner without filing the other.
Save wear on tear on your loop by setting marks on the screen at the edges (e.g. by moving masking, placing microphone stands, using a handy laser level that projects a line, whatever) and then you can get the plate quite close without the loop running in the projector. This is of course helpful if you have trouble making loops run through your projector cleanly without careful attention.

That list is not intended to be comprehensive. If you do a search on this site, you can find several threads where many of these things have been discussed, but probably not all at once.
--jhawk

Posted by Andy Frodsham (Member # 4061) on 07-11-2008, 04:46 AM:

Eric, we've run our fare share of silent movies at this theatre (often accompanied by piano). We used to physically re-align our projectors to centre them for the silent aperture, but this was a real pain for a one-off event (plus the hassle of re-aligning them for sound afterwards). I now tend to open the masking slightly wider than Academy to accommodate the offset. As for silent speed, well, we have a second set of motors fitted on both projectors which, through additional gearing, provide us with 16/18 fps. In all my 34 years at our theatre, however, I have never needed to use them once! The one time I experimented with them, the resulting speed was much toooooo slow! I think most prints you come across now will have been step-printed up to 24 fps!

You can have some good fun making-up the prints too! Without the soundtrack as a guide, you have to keep your wits about you if the print arrives twisted and/or tail out!! The captions are a real blessing!

Posted by Louis Bornwasser (Member # 3063) on 07-11-2008, 06:01 AM:

Perhaps you are "lucky" enough to have an old projector where the lens is already centered on the film. If so, you're all set; just kick the entire projector sideways.

If you have a "modern" projector such as a Century SA, you can move the lens eccentric to move the picture.

I won't mention lamphouse alignment, since you are lickely to have plenty of light and you can just "spread" is a bit to illuminate the soundtrack are better. Louis

Posted by Steve Guttag (Member # 268) on 07-11-2008, 06:50 AM:

There seeems to be a fair amount of good information here and fair amount of made up "information" as well.

Many of our clients run silent films so it is rather common for us.

First, the silent aperture was more standard than most realize...especially from the late teens through the end of the silent era (early '30s)...it had a nominal aperture of .680 x .910". Don't believe me...go and measure the FIXED apertures of the silent projectors of that era....I did! You can't go by the prints back then anymore than you can use the prints of today to determine the actual projection aperture. So Scott's advice of using a scope aperture plate as a start is probably the best "quick and dirty" method (as well as the scope prime lens being close enough). Scope currently having a .690 x .825" finished aperture.

Very early silents did use a range of apertures and often larger. You are normally pretty safe out to .725" in height but you might see things clearly outside of the desired aperture if you go beyond .930" in width.

Louis is right on Century's eccentric being handy to shift the lens. For the Simplex, I recommend changing the Upper Lens guide to the 35/70 version which will also allow the lens to shift the required amount. Unfortunately, be a 35/70 (and Studio) part, in very low production, it has gotten expensive. However it is real handy to allow precise centering of the image for all formats...especially if you have multiple projectors.

As for speeds...they are ALL over the place...some down in the 10-12 fps range (D.W. Griffith liked to conserve film and was often in the slow end of things) all of the way up to 24 fps towards the end of the silent era. However, by and large, most fall into the 18-20fps range. You can run them at 24fps but they look wrong. Unless it is the Keystone Cops or something...people walking should look natural (aside from the flicker). Many who run silent films switch to 3-wing shutters to knock down on the flicker (they didn't call them "flicks" for nothing). Since you will have gobs of light by running such a large aperture with a relatively smaller screen than normal, light is not an issue. This is a case for the Kinoton "E" projectors...they can switch to 3-wing mode, on the fly, below 20fps.

Steve

Posted by Leo Enticknap (Member # 534) on 07-11-2008, 07:17 AM:

Apart from the aperture, the other issues are the lens and the flicker.

Because of the matte between the frames on an Academy print, using an Academy lens for full-gate silent will cause it to 'overscan', so to speak. You can stop the picture bleeding onto the masking by undercutting the plate, but this will crop a significant amount of the picture. If your 'scope backing lens can be detached from the anamorph (i.e. you can unscrew it, or the anamorph swings into place on a bracket), this will do as a full-gate lens if you can't afford separate ones. If you have vertical masking you might need to nudge it down a bit to cover the frame line, and adjust the racking on the projector accordingly.

The other issue is the flicker. Most two-blade shutters will produce a visible flicker at speeds below around 20fps. The answer is a three-blade shutter, but these significantly reduce the light output. Depending on your installation, it might be possible to increase the light current to compensate, but don't try overrunning the lamp if there isn't any 'headroom', for obvious reasons (as in, premature lamp wear at best, kaboom at worst).

What's the film you're showing, out of interest?

Posted by Andy Frodsham (Member # 4061) on 07-11-2008, 10:17 AM:

As Steve said, the 'silent' projection speeds do indeed vary across prints. I can only say from my own experience that having tried our slower projection speed with the prints we have screened to date, the movement on screen did not look correct - more like slow motion! I have, no doubt, been lucky.

When we have screened silent archive prints in the past, it has always been very difficult to find out objectively what projection speed one should use (I wish they would mark-up the prints in some way). The BFI were never able to help us. More often than not, it was the pianist (having toured around the country with the print) who was able to tell us what speed we should use (always 24fps, so far)! Perhaps he just wanted to get to the pub before closing time!

Good luck with your screening.

Posted by Eric Womack (Member # 4458) on 07-11-2008, 03:00 PM:

thank you one and all for the info. I have been here at the Ohio Theater with the supposed longest running classic movie series in the USA (35 years). I have run many silents in the 5 years I have been the house projectionist. I have great variable speed motors already attached to the front of my 1940's Simplex XL's. this is just the first time I have had to file a plate since my apprenticeship in Chicago. I appreciate all of the great advice this board offers. i hope that I can help some one out.

Posted by Jack Theakston (Member # 4484) on 07-11-2008, 04:23 PM:

The standard aperture size as specified by SMPE '20s was .6795" x .906", namely 87/128" and 29/32". That was the true standard of the day.

Film speed is very subjective. Coordinate with your musical director, of course, because he may have a specific speed that the film needs to be running at. Films of the silent era were usually run two to three frames per second faster than they were shot, but this was an economic factor to get more shows in, not an aesthetic one.

Posted by Steve Guttag (Member # 268) on 07-11-2008, 06:16 PM:

Jack...might you have that standard in pdf form?

I determined my aperture size by actually MEASURING the machines of the day and what I measured and what you listed was close enough for me...I mean 4/1000ths of an inch in width and 5/10000ths in height...not too shabby. This was a nominal measurement I came up with as some were slightly smaller and some were slightly larger...they were all fixed apertures though.

As for speed...as I mentioned above...I have always used the look of people walking as a gauge...there is a certain flow or cadence to how people walk that looks wrong when projected at other speeds...one trick is to ignore the flicker when using conventional machines as that might influence your judgement. By and large, now, we use Kinoton FP30/38E projectors and they don't have flicker when running silents (well, not much of one as they switch to 3-wing mode below 20fps...so an 18fps film will have a 54Hz flash rather than 24fps' traditional 48Hz flash.

Note too, another reason for running 3-wing shutters, aside from the flicker is to protect the film by having the open time shorter to coincide with slower spinning shutter (in a mechanical machine). Since the silents are either B&W or hand colored...they will soak up the radiant engergy more so than today's color stocks.

Steve

Posted by Robert Minichino (Member # 3495) on 07-11-2008, 07:39 PM:

We did Nosferatu a couple of years ago, and I ended up running it at 18 FPS on our FP-20s (double-speed single blade shutter) without objectionable flicker (much to my surprise). I attributed the tolerability of the flicker to the double-speed shutter, as we get good light, especially in the 1.37/1.33 formats, but I don't really have a reference point.

Out of curiosity, does anyone know if there are 3 blade shutters available for the older mechanical intermittent Norelco/Kinoton projectors? I've heard them alluded to, but I've never seen one (or even a part number).

Posted by Steve Guttag (Member # 268) on 07-11-2008, 08:11 PM:

Robert...yes there were/are 3-wing shutters available for the mechanical machines as well (there was even a 3-wing for the FP16/18 machines in 16mm).

Note, since you are going from a single wing to a 3-wing, there is a gearing change as well. Both the shutter shaft gear and the intermediate gear (That drives the shutter) need to be changed....I'm not sure but the shutter shaft bracket may need to be changed as well.

Steve

Posted by Jack Theakston (Member # 4484) on 07-11-2008, 09:50 PM:

I agree, if you are running below the threshold of 24 fps, a 3-blade shutter is almost mandatory. And yes, in the day, silent films were tinted AND black and white, which did absorb a lot of light. But keep in mind, screens were also much smaller back then, too.

Steve, I don't have the SMPE papers in front of me right now, but I do have my 1922, first edition of James R. Cameron's Motion Picture Projection, an invaluable resource to those interested in theater operation of the era. He streamlines SMPE's standards for all things motion picture in these two pages:
http://www.thephotoplayer.com/standards1.jpg
http://www.thephotoplayer.com/standards2.jpg

Posted by Andy Frodsham (Member # 4061) on 07-12-2008, 01:38 AM:

Sorry Eric! On the basis of your last posting it sounds like I've been trying to teach my grandmother to suck eggs!

That's the last time I try to be a smart ass!

Posted by Stephen Furley (Member # 1277) on 07-12-2008, 03:52 AM:

There were several 16mm projectors where the shutter could be adjusted between 2 and 3 blade. The Bolex S221 did itwith a simple lever, labeled '2' and '3', which could be changed while the machine was running, some models of Graflex had a shutter which could be changed by manually sliding 2 of the blades together and locking them together with a small sliding catch, and there was a machine which made the change automatically when the speed was changed. Was anything similar ever done on 35mm machines during the transitional period from silent to sound?

Posted by Jon Miller (Member # 163) on 07-12-2008, 02:43 PM:

The Super-40 shutter used in many Kodak AV-126/256 and 250-series 16mm projectors would automatically switch between two to three blades when projection speed was changed. The centrifugal mechanism sometimes would get balky with age, though, causing more flicker if the movable blades stuck in mid-position.

Posted by Leo Enticknap (Member # 534) on 07-13-2008, 05:50 PM:

On the speed issue, herewith some VERY rough and ready pointers:

Hollywood was running relatively fast by the early '20s. From what I can gather the big picture palaces with large auditoria and long throws called for as much light as it was possible to get, hence a move from 3- to 2-blade shutters and an increase in projection speeds. 24fps was the norm by the middle of the decade, a point which is made by several people in the published papers in the SMPTE Journal and elsewhere over the standardisation of the projection and shooting speed during the conversion to sound. Pretty much anything from Billy Bitzer's mega-slow shooting to well into the 20s could have been used before the end of WWI.

Europe - From the late teens until sound, 18-22fps is typical, except Germany, which kept shooting at 16fps right up until sound.

Agreed totally with earlier posters that archives should do the research (as far as is possible) and specify a projection speed - or if the ideal or intended speed is in dispute, at the very least provide the projectionist with a note in the can detailing the best known information.