adjusting the camera's potentiometer to change the speed

[Konton]

Recently Pedro showed me I could adjust the speed of my Bauer T610 projector. I did this by opening the projector and adjusting the potentiometer inside. I was curious if most of the later 70's early 80's equipment had this option, so I opened my Goko RM-8008 editor, found the potentiometer, and did the adjustment. The Bauer T610 had only one. The Goko RM-8008 has two (one for 18fps and one for 24fps). I was just curious if anyone has ever tried this with their camera. Do some cameras also use potentiometer's to adjust the speed internally? If so which ones? As most cameras seem to run at a steady speed, it would seem to be it would be nice if techies like us could calabrate the camera to run as close to 24fps as we can without the use of a crystal sync. I was able to get my Goko RM-8008 to run almost exactly at 24fp. I was losing a frame every two minutes!

[jessh]

Will most likely work on most electronic cameras. There is a chance of some not having a pot in which case you could probably replace the right resistor with one. What did you use to measure the speed? I have contemplated opening up my Canon 310XL to do this.

~Jess

[Lunar07]

The Bauer T610 had only one. The Goko RM-8008 has two (one for 18fps and one for 24fps).

Why would the Goko have two? Is it because it has a switched speed, and the Bauer have a variable speed control?

[Konton]

Jessh, Let me know if you open up the Canon 310XL and try this. I have this idea to buy a bunch of Canon 310XL's and make them all run at 20fps. Over at the ATA we have a Elmo TRV-S8. It usually transfers at exactly 20fps. I have checked it out and it's 20fps exactly. I figure if we had a bunch of basic cameras all running at 20fps, we could rent them out with free telecine transfers. Everyone would have a much better chance then of synching audio using wild sound.

Lunar. Actually, the Bauer has one, and there is no variable speed control. The Goko has two, and does have the variable speed control. I have no idea why though. I'm not much of an electronics guy.

[Lunar07]

Jessh, Let me know if you open up the Canon 310XL and try this. I have this idea to buy a bunch of Canon 310XL's and make them all run at 20fps. Over at the ATA we have a Elmo TRV-S8. It usually transfers at exactly 20fps. I have checked it out and it's 20fps exactly. I figure if we had a bunch of basic cameras all running at 20fps, we could rent them out with free telecine transfers. Everyone would have a much better chance then of synching audio using wild sound.

Lunar. Actually, the Bauer has one, and there is no variable speed control. The Goko has two, and does have the variable speed control. I have no idea why though. I'm not much of an electronics guy.

I have been thinking of ways to alter the speed of a R8 Zeiss Ikon Moviflex which runs at the sinlge speed of 16FPS - to alter it to run at 20FPS. Problem, it is the only Zeiss Ikon Moviflex R8 that I have. No room for error.

[Lucas Lightfeat]

I am no electronics expert, but I believe that a multimeter attached to a flash socket should give a readout of the camera running speed, as the flash socket is triggered by the shutter, for obvious reasons. This is probably the best method, where possible.

Alternatively, a stroboscope can be bought or borrowed (or even made), which can be set up for a particular oscilation, and the camera harmonised to it through the lens to gate aperture. A good stroboscope is expensive though.

I may be wrong about the above, but no-one else cut in yet, so...
...please correct me boffins and eggheads.

Lucas

[Konton]

Lunar07, those cameras are from the early 70s, right? Think they have something in them that would let you make the modification?

Lucas, well the flash contact and a frequency counter could work, but I've been going through the big ole book of Movie Cameras. Less than have of the super 8 camera out there actually had flash contacts. So I'd rather look at other alternatives to gauge the speed of the camera as it's being modified.

Not sure what kinda stroboscope you are talking about. But I use a Speed Checker to verify my camera speed.

http://www.tobincinemasystems.com/page7.html

It's $99 and I have used it to test all my cameras as well as calibrating the speed of projectors and editors. Works pretty well. Too bad it doesn't run at 18fps. But it does 24fps and 20fps, so ....

[BK]

I was able to get my Goko RM-8008 to run almost exactly at 24fp. I was losing a frame every two minutes!

Did you get the speed checking thing with yours? A round disc with some markings on it? You attach the disc on the rotating spindle of the mirror prism and adjust using the speed knob on the editor till the lines on the disc becomes stationary for the exact running speed. Can't remember what the thing is called though.

Bill

[BK]

Of course, it's called a stroboscope. Doooooh !

Bill

[Lucas Lightfeat]

Lunar07, those cameras are from the early 70s, right? Think they have something in them that would let you make the modification?

Lucas, well the flash contact and a frequency counter could work, but I've been going through the big ole book of Movie Cameras. Less than have of the super 8 camera out there actually had flash contacts. So I'd rather look at other alternatives to gauge the speed of the camera as it's being modified.

Not sure what kinda stroboscope you are talking about. But I use a Speed Checker to verify my camera speed.

http://www.tobincinemasystems.com/page7.html

It's $99 and I have used it to test all my cameras as well as calibrating the speed of projectors and editors. Works pretty well. Too bad it doesn't run at 18fps. But it does 24fps and 20fps, so ....

It says on the tobin speedchecker page that it's only for cameras with a mirror shutter, and if you don't have a mirror then you have to remove the lens and the gate?!?!?! As a prism camera (like a Super8) has the prism in front of the shutter, you need to look through the gate itself to read the lights, which isn't possible on some cameras, surely. Pro camera companies use a stroboscope I believe, which is a light that flashes at 24fps, for example, but is constant when viewed through the gate of a camera that is running correctly.

I like the multi-meter and flash socket idea, where possible. It should be extremely accurate too, and give a digital readout of the precise speed. It is using the flash socket that the crystal systems "The Film Group" make can read the speed of the camera. That's why they only convert cameras with a flash socket.

Lucas

[jean]

What kind of multimeter would that be? No laughter, please, but a hint! I only know model which measure voltage, ohms, and amps. The flash socket solution is indeed very simple (and obvious!).

[S8 Booster]

What kind of multimeter would that be? No laughter, please, but a hint! I only know model which measure voltage, ohms, and amps. The flash socket solution is indeed very simple (and obvious!).

A fluke M87 has an option of very accurate frequency measuring - also records min/max frequence and (If I remember correctly average)

A small battery like 1.5v in series with the meter/flash contact vill supply sufficient voltage.

Expensive but fabolous:



R

[danpuddick]

hej

I checked my camera's speed by hooking up my pulse generator (sound sync unit), like the one pedro sells to my PC soundcard input. I used soundforge (although any program which can record audio with an accurate timeline would work fine) to record as my camera ran at it's various speeds. I could just look at the time line and see the time between each pulse, thus seeing how fast the camera was running and how long it took to get up to speed.

I just did this for interested - I don't planning on opening anything up and fiddling with it just yet but it gave good results.

I guess this would only work on a camera with a flash contact.

good luck

daniel

[Lucas Lightfeat]

What kind of multimeter would that be? No laughter, please, but a hint! I only know model which measure voltage, ohms, and amps. The flash socket solution is indeed very simple (and obvious!).

I think that ohms is cycles per second, and so the falsh socket should be 24ohms precisely, but I don't have a multimeter so I can't verify this. Anyone?

Lucas

[Konton]

A round disc with some markings on it? You attach the disc on the rotating spindle of the mirror prism and adjust using the speed knob on the editor till the lines on the disc becomes stationary for the exact running speed. Can't remember what the thing is called though.

I forget as well, but I don't have one. I use the speed checker by pointing the LED's at the rotating sprockets. If the sprockets are stationary, then the machine is running at that speed.

It says on the tobin speedchecker page that it's only for cameras with a mirror shutter, and if you don't have a mirror then you have to remove the lens and the gate?!?!?! Pro camera companies use a stroboscope I believe, which is a light that flashes at 24fps, for example, but is constant when viewed through the gate of a camera that is running correctly.

Then this is a stroboscope. Because it has the LED's all flashing at 24fps. I admit, the speed checker works much better on my Beaulieu 7008 Pro and my Fujica CZ1000. I can look though the viewfinder to see the changes. For prism cameras, I have to use a mirror. I prop the small mirror next to the gate inside the camera so I can see the speed checker through the lens. I have tried this on all my Nizo cameras and it works fine.

I like the multi-meter and flash socket idea, where possible. It should be extremely accurate too, and give a digital readout of the precise speed.

I would too. But unfortunately it can't be done on all cameras. I'd like to change the speed of a Canon 310XL, so I don't have this option. I'd need the flash contact installed for that. PLus it can't be used to calibrate projectors as one of them that I know has a flash contact.

I looked up those Fluke 87's, but I think you could just a a bench frequency counter. You don't need something so portable. But if you wanted a Fluke 87 you might be able to get a used one for under $100 of Ebay. Anyway I got bored one day and decided to connect my camera to my computer to try this. I found this software.

http://www.circuitsonline.net/download/view/12

It didn't work well, but perhaps I just don't know how to use it.

I have this idea of getting a infrared emitter and a reciever, like they used to watch the speed of the perfs moving though the old reel-to-reel recorders, and placing one in front of the lens, and the other in the gate. Hooks this up to a multimeter to measure the frequency. It could be used with any camera.