|
This topic comprises 2 pages: 1 2
|
Author
|
Topic: Apeture plates
|
|
|
|
|
John Hawkinson
Film God
Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002
|
posted 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
| IP: Logged
|
|
Andy Frodsham
Expert Film Handler
Posts: 238
From: Stoke on Trent, Staffs, UK
Registered: Nov 2006
|
posted 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!
| IP: Logged
|
|
|
Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
|
posted 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
| IP: Logged
|
|
Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
|
posted 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?
| IP: Logged
|
|
|
|
|
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 2 pages: 1 2
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion
and agrees to release the authors from any and all liability.
|