5 bladed projectors vs 3 bladed ones

[Guest]

So far, I've been using standard 3 bladed projectors for a while now, but I'm thinking about picking up 5 blade. Is there much of a diffrence? I'm all ears...

[MovieStuff]

So far, I've been using standard 3 bladed projectors for a while now, but I'm thinking about picking up 5 blade. Is there much of a diffrence? I'm all ears...

I'm not sure what you're asking but here is what I can tell you based on experience of building both types.

If you are working with NTSC, then the idea is to make the projector and the camera both "blink" at the same time to eliminate flicker. A projector with a three bladed shutter means that each frame will "blink" on and off three times per frame change. NTSC video has 60 fields per second, which means it is effectively "blinking" 60 times a second. 3 divided into 60 = 20, which is why you end up at approximately 20fps with a three bladed shutter since that is the frame rate needed to make them both "blink" in synch.

Now, a five bladed shutter is a bit different. 5 divided into 60 = 12, which is an even multiple of 24. That's why you can run your film at 24fps and not get flicker with a five bladed shutter on NTSC. I've never done it but I would imagine you could also run it at 12fps with a five bladed shutter, if necessary, as the math seems to work out the same.

Installing a five bladed shutter doesn't always work on all projectors because the pulldown sometimes isn't fast enough and to accomodate the smaller blades.

In either case, you camera must be locked to 1/60th of a second.

Hope that helps!

Roger

[FILM-THURSO]

The Kalee model 12 35mm mechanisn has a Drum shutter which rotates behind the aperture. It works as a two blade system blinking twice per frame- open close open close/move open close open close/move etc. Very good quality machine, rock steady bright projection!

[pheboglobi]

Does anyone know which projector models have 5-blade shutters? Or a link that has that info listed?

Thanks,
Garrett

[leadlike]

I pulled off a very rediculous stunt once-
for my B&H 16mm projector, I made my own five bladed projector. I had one of the really crummy 'school projector' models that didn't have too many miles left on it anyway, so I gave it a try. I found that the blades on the original shutter covered 50% of the possible area, so I made a five bladed template from that information. I next cut out five blades from a readily available source- soda cans! I cut the original blades out of the projector, and glued the new blades into their appropriate places on the shutter wheel, flipped the switch, and it actually worked!
But it was very noisy, as the blades rattled around inside quite a bit, but hey, I only needed to transfer over some silent film anyway! The blades outlasted the projector, which finally died of a bad belt/electrical problems a few months later.

[FILM-THURSO]

The Kalee Model 12 with 2 blade drum shutter dates from the mid-late 1930's and is still going strong! Long live the drum shutter!!!!