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Bell & Howell 16mm Specialist Projector


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#1 Canney

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Posted 05 May 2006 - 02:36 PM

Hey does any one know if these projectors have multiple frame rates like 18fps and 24fps or a vari speed control thanks.

I was also wondering if any body has taken a video camera and filmed the image off the wall. Does it have a flicker?
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#2 Clive Tobin

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Posted 05 May 2006 - 03:25 PM

Hey does any one know if these projectors have multiple frame rates like 18fps and 24fps or a vari speed control thanks. ...I was also wondering if any body has taken a video camera and filmed the image off the wall. Does it have a flicker?


This has been discussed many times and the answers are:
1. Assuming you are in North America, you will be shooting NTSC video so you need 60 (really 59.94) flashes per second, or a whole multiple thereof, coming out of the projector shutter to avoid flicker.
2. The normal 16mm projector has a 3 blade shutter, so you will get 72 or 54 flashes per second coming out, at 24 or 18 FPS respectively, which will give you bad flicker in the video.
3. To prevent flicker you would need a 5 blade shutter for 24 FPS, 3 blade for 20 FPS, or 4 blade for 15 FPS.
4. To prevent flicker or pulsation the projector speed must likewise be controlled to within a fraction of a percent of the above mentioned speeds. Ordinary projectors with non-sync motors generally run a few percent fast. To get a close speed you need either a synchronous AC motor or crystal DC motor, with timing pulleys and timing belt drive instead of a smooth belt.
5. To get a good quality image you need a direct or aerial image with no screen.

Shameless plugs: We sell 8mm and super-8 telecine transfer machines and will also be making 16mm later when we get caught up with our present orders. These of course do the job properly, with direct imaging to the sensor without any screen, mirror or field lens and are flickerless. Also we transfer film to video at low rates. Kindly check out the website at http://www.tobincinemasystems.com .
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#3 Charles MacDonald

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Posted 05 May 2006 - 08:07 PM

3. To prevent flicker you would need a 5 blade shutter for 24 FPS, 3 blade for 20 FPS, or 4 blade for 15 FPS.

I recall talking to a brodcast enineer once who decided tha the way to get a GOOD telecone was to build an Excentric into the projector to get a variable pull down. He just sent the drawngs to a machine shop and got what he wanted. The unit he built showed one frame for 3 fields of the video camera, and then the next frame fo two fields, then back to three. He of course had the motor clamped to the "house sync" at the atation.

The otehr wway is to use a prisim movemnet like a Movie viewer, or a editing table to present a flicker less image to teh TV camera . Risk is that many fields will contain an image from more than one frame.

MY ebay serches did show an Extaman TV projector manual today. ( Item number: 9719605304 ) You may want to chek that out and attempt to findsome documnetation.
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#4 Canney

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Posted 07 May 2006 - 02:18 PM

Actually what I do with S8 mm is film in PAL for 24fps and NTSC for 18fps. I usually lock in the shutter speed on my camera and don't get any flicker at all. My camera has multiple shutter steps so its not really an issue for me when it comes to illimintaing flicker, my camera does a pretty good job of that even when it on auto. The thing is I just need to know if a certain projector can play back at a certian frame rate.

I was curiouse as the the specifics of the B&H projectors cause I can find them cheap enough on ebay. But actually I might just get one and make a five blade shutter for it out of sheet metal. It would be cheaper than buying an elmo projector with one built in. That way I wouldn't have to shoot PAL and then convert to NTSC like I normally do for 24 fps.

The reason I was asking about if the B&H projectors had a 18fps options on them was because I can eliminate the flicker through the camera and go straight to NTSC.

I am not sure about what speed the 30,800 feet of film I was given to transfer was shoot at but I would probably guess 24 fps. So I'll either by some projector and make a crazy contraption out of it or will shoot PAL and then transfer.

As to the tobin systems I have looked into them before and have considered it along with the sniper systems. If I get into film more I probably will get one. But for now I have to keep it cheap.
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