Hi Guys
We are in the process of building a stop-frame/time-lapse motor for our cameflex 35mm camera.
So the motor I'm using is a 15rpm 12v motor…So its quite slow which is good for stop motion. I'm planning on shoving an esc and servo tester on it to control the speed to go slower…but before I do that i need to work out a pipeline of how to test the shutter speed…..so I'm thinking its 15rpm so 15 divide 60 secs = 4second s….but the film is only exposed for a fraction of the time it takes to spin the mirror …It says 1/30 is what i have the shutter angle set to, but not sure if that counts for long exposures? …when i look at the movement of the shutter with its lens off ...it looks about 1second that the film is exposed. So would i use a light-meter to measure either side of one second and take frames with all the aperture settings …at the same time shoot a test with the aperture written in front of camera….then write down what the exposure should have been compared to the aperture …that should give the shutter speed right?
We do have video cameras that shoot slowmo …would that be a better way to measure?
If you know the frame rate of your slomo video camera, then you should be able to extrapolate the shutter speed of the movie camera by just video recording the shutter movement and then counting video frames.
Years ago, I needed to sort out the shutter speed of a very slow running Bolex. I rigged a light to shine through the gate to start and stop a photo cell/relay attached to a digital darkroom timer. I started the motor running and then engaged the circuit when the shutter closed. The shutter opened, which started the timer, then the shutter closed, which stopped the timer. But I think using the slomo video is brilliant.
Also, you might consider using a capping shutter instead.
Hi Roger... thanks for the feedback. I like the light through the gate timer technique….Yep I have my eyes peeled for a capping shutter but they are hard to come by these days.
What i have done in the past to find out the rpm of a modified winch motor using a slow mo camera was to put a wall clock next to the motor with a mark on the motors shaft…..then it was just a matter of counting the revolutions compared to one revolution of the seconds hand on the wall clock….I might try it with a stopwatch sitting next to the cameflex shutter and count the milliseconds.
milesandjules wrote:Hi Roger... thanks for the feedback. I like the light through the gate timer technique….Yep I have my eyes peeled for a capping shutter but they are hard to come by these days.
I been building this partly 3d printed partly aluminium animation motor. It does 1-3 second exposures and has a nice new frame counter curtisy of ebay. I'm using a reed switch to stop the geared 15prm motor each frame. The reed switch is both a normally open and normally closed switch.
So NC is used to stop the motor after each exposure and NO is used to trigger the frame counter.
