'Double Shutter' Century's

[John Eickhof]

jim, its a simple procedure, replace the C2-D55 assy with the conventional C1-D-45 bearing holder, then install a 90 or 92 degree shutter on the hub with the smaller diameter and adjust the existing collar to set up end play in the shutter shaft, thats it! if the head has an old type dual one piece GR-207 leave it alone, if there is 2 GR-207S, leave them in place and you will have a built in spare gear in case of damage just remove setscrew on the damaged GR-207 them slide the spare in place !

[Jim Cassedy]

Just for fun- - (for those who've never seen one) here are a couple of photos
of the double shutters in the Century JJ's I work with here in San Francisco

The Blade Closest To The Gate Turns Clockwise, The Other Runs Opposite
CenturyShutter_7.jpg

Here Are The Shutters In The Full Open Position
CenturyShutter_2.jpg

[Brad Miller]

I hate those shutters (and the double). If you look closely the pulldown isn't even done before the center of the image starts to permit light through it. Then it will start pulling down the next frame before the light has been blocked from the center of the image. And the weird horizontal hot spot too. Ugh. To fix simply swap out the shutter "bowtie" closest to the gate and lose the rear one.

[Dave Macaulay]

Right. The smaller diameter shutter shaft is direct and the larger sleeve shaft is through the reverse gearing. A single shutter on the small shaft will work. Keep the reversing years greased though so they don't seize up. Drop some oil between the shafts too.
If anyone has a pair of dual blades they don't want, I will take them!

[John Eickhof]

now that i think about it brad, you are right on and i think thats what mark was explaining in his post about hot spot and jitter in center of picture, i too think single shutter is more effective on a century unless your in a drive in where a higher degree of ghosting is acceptable in order to gain 5 or 10% more light, the XL did it better with the high speed itermittent, it had about 10% longer dwell time thus the shutter was smaller giving more light on the screen. the sad part was that there were not many rebuilders that would work on the HS and TV movements, the TV int. had a slipper block and eccentric star that alternated from 4:1 and 5:1 pulldown speed every. other frame. dave, pm me i probably have a couple sets of new diamond shutters

[Steve Guttag]

Century always had a struggle getting light through the projector with the shutter blades that far back from the aperture. That is also why they were prone to ghosting (varied with the lamp reflector and lens). Simplex was more efficient with light on the XL (Xtra Light) and their conical shutter. Simplex also cut the aperture evenly, not in a sea-saw fashion.

One definitely gets more light on a Century double shutter (even without the "V" cut in it) but, as mentioned above, there is a price for it on light distribution and perceived flicker.

Christie went though a similar issue on their P35 line and how far back their shutter was and how tiny it was. Their solution was that of Norelco's...make it single wing and spin it twice as fast. That still only made it about as good as Simplex as their velocity is still a function of shutter diameter.

Kinoton tried to do a single wing on the FP75E...it tore itself up so they went with a dissolving shutter which, due to the gear belt doesn't flicker like a Century but it definitely has a strobe like effect to it on the normal "2-wing" mode. Their virtual 3-wing looks fine.

FWIW, I prefer the steel blades on Century over the aluminum ones. It stabilizes the shutter(s) better. It has an overall better look, to me.

[Marcel Birgelen]

Just for fun- - (for those who've never seen one) here are a couple of photos
of the double shutters in the Century JJ's I work with here in San Francisco

The Blade Closest To The Gate Turns Clockwise, The Other Runs Opposite
CenturyShutter_7.jpg

I've never seen those with my own eyes, but they look evil and dangerous... more like a vegetable chopper than a "light chopper".

[Jim Cassedy]

Well, Marcel, there's normally there's a protective cover over the blades, but yes- - they can
definitely be quite finger-unfriendly if you're attempting to adjust them with the safety covers
removed. I got my finger cut while working on a regular shutter once- - so I'd imagine these
would be twice as bad!

[Mark Gulbrandsen]

I hate those shutters (and the double). If you look closely the pulldown isn't even done before the center of the image starts to permit light through it. Then it will start pulling down the next frame before the light has been blocked from the center of the image. And the weird horizontal hot spot too. Ugh. To fix simply swap out the shutter "bowtie" closest to the gate and lose the rear one.

The best are the single blade steel shutters. Now one would have to make his own, or have them made. The originals were also dynamically balanced due to slight thickness differences around the steel used.

[Mark Gulbrandsen]

The Cinerama 70mm only version of the JJ had dual shutters made of steel, but they were spring loaded through the shaft mount so it helped reduce pulsation against the gear train during pull down. In theory extending the life of the gear train. You can feel this slight pulsation if you run a 70mm loop and put a slight resistance on the shutter shaft. Anyway, I converted that machine to a single blade anyway... The screen was only 40 feet wide and only a 3kw lamp was needed for 70mm. No Jet Arcs or Super Cinex at this location!

[Helmut Maripuu]

Sweden, AGA projectors with drum apertures were manufactured
ps://www.filmsoundsweden.se/backspegel/aga_proj.html

www.filmsoundsweden.se/backspegel/aga_proj.html