Film-Tech Forum ARCHIVE: Shutters & Parts

This is topic Shutters & Parts in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Dave Bird (Member # 490) on 09-29-2000, 07:29 AM:

What is the difference between a 3-bladed shutter and the standard 2? Also, where can I source some new parts for my Simplex XL's (either here in Ontario or wherever). Thank you.

Dave Bird

Dear lord, somebody help, the Vegemite's on FIRE!

Posted by Barry Floyd (Member # 385) on 09-29-2000, 07:42 AM:

Dave,
My projectors are as old as yours and I just ordered and recieved parts for my XL this week. I downloaded the Parts Manual from Film-Tech, found my part numbers, and ordered them from CPI in Nashville.
The guys at CPI (Cinema Products International) were very helpful and very quick with getting me the parts.

Speaking of Shutters & Parts....

The "dowser" or "thingy" that's connected to the changeover cable has been disconnected and just kind of "flops around". The "fire shutter" doesn't reset either. My question is, since I'll be running this XL with a platter... do I still need these parts inside the machine?
Somebody shed some light on this for me?

Posted by John Walsh (Member # 168) on 09-29-2000, 10:08 AM:

A 3-bladed shutter is mostly used when transfering TV images to video. The fields/frames are different between TV and film, and a 3-bladed shutter compensates for this. They are also used insome review rooms to get a picture with less flicker.

I would keep the changeover shutter, usually referred to as the "zipper" after a company that manufactures them. It looks nicer to not see the countdown, writing and other stuff on the film.I would also keep the safety shutter. It usually does not break, and helps prevent the film from burning if the projector slows down. For example, if the projector belt breaks, or the fuse on just the motor opens, the automation will not "know" and not shut off the lamp.

Posted by John Pytlak (Member # 331) on 09-29-2000, 10:32 AM:

I agree with John that it's a good idea to keep the centrifical "fire shutter", since it will protect the film from burning if the projector slows or stops. Many modern projectors leave these out of their designs, since they were only mandated for nitrate film. But saving any print from a burned frame is worthwhile.

AFAIK, projectors intended for telecine (film-to-video) use a FIVE blade shutter, along with a special fast pulldown, to achieve the 3:2 pulldown frame rate conversion from 24 fps film to 30 fps video without flicker.

3-blade shutters are widely used in screening rooms, to almost completely eliminate any perception of shutter flicker (3 x 24 = 72 interruptions per second, so flicker is much less visible). A 3-blade shutter can also be used in theatre applications to minimize flicker, as long as you have enough light to overcome the lower shutter efficiency. Using a 3-blade shutter to minimize flicker, I've projected prints at light levels up to 60 footlamberts on a smaller screen, and they look stunning. The current screen luminance standard of 16 footlamberts specified by SMPTE 196M (with an allowed range of 12-22 fL for theatres) was primarily driven by the need to reduce flicker perception with a 2-blade shutter having only 48 interruptions per second.

For a home theatre with a small screen, and excess light, using a 3-blade shutter would offer the advantage of almost no flicker, and the ability to increase the light level well above 16 footlamberts, to see that "brighter is better" usually produces stunning images.

Of course, when showing silent films at 16 fps, a three-blade shutter must be used, since flicker with a two-blade shutter would be very annoying.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Posted by Dave Bird (Member # 490) on 09-29-2000, 11:15 AM:

I have heard the term "drive-in shutter". Which setup (or combination of) is this?

Also, is the "hub" of the conical shutter on the XL part of or seperate from the blade itself? (One of mine is cracked, will I replace the whole blade or just a hub piece? I can't tell from the parts diagram.)
Thank you for the replies.

------------------
Dave Bird

Posted by Dave Bird (Member # 490) on 09-29-2000, 11:23 AM:

Barry, I had that "fire dowser" problem as well, until I had realized that it had simply wedged with another part during transit. Now it's fine. Of course, I have the advantage of no lamp attached, so I can get at this stuff easily. (The disadvantage of not being able to light 'em!)

I don't want to say rust, but the pitting in that area of the projector made it a little difficult to disassemble the c/o zipper dowser from the cable. Before I re-attach them, what can I use to protect these little allen screws from sticking next time. Or is it such a high heat area (and so rare that you'd need to get the cable out) that I should forget it? What will clean the (very slight) pitting in this area? Thank you.

------------------
Dave Bird

Posted by John Pytlak (Member # 331) on 09-29-2000, 11:31 AM:

A "drive-in shutter" may be one of two things.

A conventional 4:1 "Geneva" intermittent using a maltese cross movement requires a nominal shutter blade of 90-degrees to block the light during the film pulldown. (See Tim Reed's excellent animated video of how an intermittent works in the "Videos" section of Film-Tech). Otherwise, light going through the film while it is moving will cause "travel ghost" on the screen. With the low light levels typical in a drive-in, a shutter blade under 90 degrees might be used to gain slightly more efficiency at the expense of a bit of travel ghost.

Special high speed "drive-in" intermittents used an extra mechanical linkage to decrease the pulldown time. A 5:1 high speed intermittent could advance the frame in only about 72-degrees (360/5 = 72). So the shutter blades used with these intermittents could be as small as about 72 degrees, putting even more light on the screen. The disadvantage of the high speed intermittents was that the extra linkage made them noisier and more problematic. The higher film accelerations also put more stress on the film perforations, which was more of an issue on triacetate prints than today's tough polyester prints.

Posted by Mark Gulbrandsen (Member # 72) on 09-29-2000, 12:29 PM:

The 3 blade shutter should be available from Strong. Many studio and home screening rooms use them.
For Telecine a 5 blade shutter is needed as well as a synchronus motor driven sound head.

I ahve installed high speed movements in Drive inns recently and found far more image definition and apparent steadiness with them.
Mark

Posted by Brad Miller (Member # 2) on 09-29-2000, 12:45 PM:

I'm probably wrong on this, as I've never bothered to research it, but isn't/wasn't Simplex the only high speed intermittent around? Are they still being made?

Posted by John Pytlak (Member # 331) on 09-29-2000, 12:57 PM:

AFAIK, "drive-in" intermittents are only available on the used equipment market. Don't know if Simplex was the only type, and whether having the extra linkage was the only design.

Mark: When you saw the improved definition and steadiness, could it be that you were using it with 90-degree shutter blades? If the film was pulled into position within 72 degrees, it would have more time to stabilize in the gate before the shutter opened.

Posted by Mark Gulbrandsen (Member # 72) on 09-29-2000, 01:37 PM:

Actually Phillips made high speed intermittants for the FP-20 series of projectors. The Century CS-55 movements are also High Speed.
Mark

Posted by John Pytlak (Member # 331) on 09-29-2000, 02:16 PM:

Mark:

Did the Century CS-55 movements get adapted for use in the Century JJ 35/70? Over on r.a.m.t, they are looking for evidence that 55 mm prints of "Carousel" and "The King and I" were actually used in theatres. Where were the projectors installed? Were they 6-perf or 8-perf pulldown? In any case, with a high speed movement, the stress on the perfs had to be pretty high, especially with triacetate prints.

Posted by Rory Burke (Member # 512) on 09-29-2000, 02:37 PM:

There is a theater in southern California in the Inland Empire with a three bladed shutter presentation. We found that we lost more light and had to beef up the lamp house from a 3k to a 4.5k bulb to compensate but as it looks on the screen now it is just.....LIQUID!.....The Star Wars remastered releases looked spectacular on that screen.
It is the CinemaStar Perris Plaza 10 all THX complex in the city of Perris Calif about 80 miles east of L.A.

Rory

Posted by John Pytlak (Member # 331) on 09-29-2000, 03:01 PM:

Rory:

I'm not surprised at the quality you are getting with a 3-blade shutter. Certainly gets rid of flicker, and allows a high level of illumination. As you note, the lower efficiency of a 3-blade shutter needs a larger lamp for a given image size.

What size and type of screen are you lighting with that 4500 watt lamp? What is the screen luminance? With a curved gain screen and decent optics, I would guess a screen up to about 20 x 48 feet would be possible, even with a 3-blade shutter.

Posted by Larry Shaw (Member # 388) on 09-29-2000, 03:11 PM:

John, I believe the EE predates the JJ. I also don't recall the movement being accelerated, I'll check someday. It does have double dissolving shutters, but made from thick, heavy metal. Stop by and have a look if you're in the area.

-Larry

Posted by Rory Burke (Member # 512) on 09-29-2000, 03:22 PM:

John P <BOWS> <BOWS> <BOWS>

You are the film-tech guru I tell you. The screen size is 19.3 x 45.3 to be exact and with in you calculation's specs at that. Since that screen is THX it has a luminance of 16ft/Lamberts +/- 2ft/Lamberts.

Rory

Posted by Mark Gulbrandsen (Member # 72) on 09-29-2000, 06:20 PM:

John,
On the several occasions I used high speed X-L's I noticed improved definition in all cases. That's one reason I installed them at the D.I. at Bass Lake Indiana. In all cases they utilized wider than normal shutter openings to achieve brighter on screen images which they did. You can observe how bright it can be right here on the Film-Tech picture page. Go to the Cinema Borealis pics and check out how bright the on screen "RAN" picture is compared to the Chicago skyline. This is a bright skyline and we had no trouble overcomming it with a high speed machine and 4kw lamp. This was my second use of a high speed machine.

Larry,
The CS-55 movement that I had was definately accelerated at least a little bit. If you rotate the machine over and look through the sight glass of yours you should be able to see that the cam pin is mounted in a sliding dovetail on the cam. This dovetail is operated by a roller bearing that rides on an inner cam behind the main cam. The other end of the dovetail also has a pin that sticks through the main cam. I don't think it was a very good H.S. design but what can one do with a Century movement in this department without a major re-design. This had to be very hard on acetate film even though Fox holes are stronger. It may also be a major reason that CS-55 was never accepted as a projectable format. I'd be curious to know if yours is the same.
Best,
MARK

Posted by Steve Guttag (Member # 268) on 09-29-2000, 08:43 PM:

John,

With traditional intermittents, you are correct about silent films and the need for more than two flashes per frame but with the new breed of electronic intermittents silent films can finally come into vogue! ;-)

Since the electronic intermittent's speed isn't dependent on the sprocket speed anymore, the shutter doesn't have to slow down either when projecting at slower speeds.

We just installed a pair of Kinoton FP-38ES (35/16mm) projectors at the National Gallery of Art in Washington DC. You can adjust these machines on the fly from 10fps - 30fps and the flicker doesn't change! They all look like 30fps with a double shutter! Since the intermittent is so quick, the light efficientcy is also outstanding. The other wicked thing about the electronic intermittent machines is the framing...you can roll the picture infinately (like an old TV with the vertical hold out of adjustment)...the loops never look like they change size!

Anyone considering showing silent films, really should check out a pair of electronic intermittent machines.

------------------
"Old projectionists never die, they just changeover!"

Posted by Gordon McLeod (Member # 33) on 09-29-2000, 08:45 PM:

The phillips FP7 was thee first that was available with a high speed pulldown it was called the Super7
For telecine they used a special movement on the XL driven by its own selysen motor independent of the shutter.
The DI movement was not fast enough for telecine

Posted by Gordon McLeod (Member # 33) on 09-29-2000, 08:53 PM:

David get me the part numbers

Posted by Tim Reed (Member # 137) on 09-30-2000, 06:32 PM:

Simplex XL telecines also used a 3-bladed shutter, spinning at, I believe, 2160 rpm... and the intermittent's speed was geared to oscillate at a rythym which produced the requisite 3:2 pulldown rate.
It still worked out to be the same as a normal projector with a 720rpm, 5-bladed shutter an a 3:2 intermittent, but Simplex used a different approach.

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Better Projection Pays!

Posted by John Pytlak (Member # 331) on 10-02-2000, 01:23 PM:

With the availability of very high speed pulldowns (either "drive-in" intermittents or electronic pulldown, moving from 48 interruptions per second (typical 2-blade shutter) to 72 interruptions per second is now a viable option for many theatres. It virtually eliminates flicker.

The strength and durability of today's polyester print film can better withstand the higher accelerations from these high speed movements, allowing theatres to take advantage of increased light efficiency.