testing sheet for speed accuracy of camera

[kontrabass888]

I am looking for a testing sheet for speed accuracy of camera, which I could print out,
and then glue on a small plate to plug in to the rewind connection of my bolex cameras.
it looks like the speed testing sheet for record players(LP player,turntable)
it it possible to download from internet?

[granfer]

The correct name is "Stroboscope Disc (or Wheel)". There are design programs on line, but they usually relate to common speeds, such as those for records.

Better idea is a black disc with white dots around the edge and use a cheap digital optical tachometer to read the speed........

http://www.ebay.co.uk/itm/Digital-Laser ... 5402086d8d

Divide the reading by the number of dots to get the shaft speed, the more dots the more accurate the answer. They do not need to be accurately spaced, or even all the same size.

[kontrabass888]

thanks granfer, I found a video of digital thermometer on youtube. it looks pretty easy to use.
however, I got a question now: in this way I can read the speed just by press the trigger , but how to calculate the correct speed ?
because if the rewind connection doesn't run at 1 second per round(turning), it will be difficult to calculate the correct speed.

[kontrabass888]

because if the rewind connection doesn't run at 1 second per round(turning), it will be difficult to calculate the correct speed.

[granfer]

First... NOT "digital THERMOMETER"... "digital TACHOMETER" !!!!!!!!

The Tachometer reads the number of dots passing its beam in 1 SECOND. So if twenty dots pass in 1 second on a 10 dot disc the speed is 2 revolutions per second.

First, you need to know hoe many frames are rewound by one turn of the rewind shaft. Do this by putting a length of scrap film in the camera with a marked frame in the gate. Rewind 1 turn. Mark the frame in the gate, remove the film and count the frames rewound including the first marked frame but not the last marked one.
That gives you the number of frames per turn of the rewind shaft3eew... "X"

For 24 fps the rewind shaft will revolve 24/X revolutions per second. For 16 fps it will do 16/X revolutions per second... etc,etc.

So for 10 dot disc, camera speed 24 fps, the tachometer will read 10 x 24/X revs/sec.
If it is calibrated in revs/minute it will read 60 x 20 x 24/ X revs/min.

OK?

[bolextech]

If your tachometer works by shining a light or a laser, just shine it directly on the advance claw.

Jean-Louis

[Will2]

Old timers in the industry call the strobes that test for speed accuracy "crystal pistols". The ones I've seen look like a silver gun. Similar to what mechanics use on cars to check timing I think.

Those will just tell you if it's at 24fps (or 25) and you adjust the camera until it's locked on...used obviously to test crystal sync for audio. Adjusting the speed isn't easy from what I hear on crystal cameras.

They also use fancy (re: expensive) oscilloscopes but I couldn't tell you how.

My tech told me that Arri camera specs say that in a million strobes it shouldn't be off more than 3 times.

[BAC]

I use a digital tachometer to check the speed of my Regular 8mm cameras. I remove the lens and load a test roll of film into the camera. The speed may be different when it has the resistance of the film plus the film is bright enough for the digital tachometer to detect. I point my digital tachometer at the shutter to get a reading. It gives me a reading in RPM which I convert to frames per second. 18 frames per second = 1080 RPM (18 x 60 = 1080). I also use it to check the turntable on my stereo. I just place a piece of foil on the turntable and let the digital tachometer read from that. I'm not sure how this would work with a Super 8 camera with a fixed lens.

[Will2]

I use a digital tachometer to check the speed of my Regular 8mm cameras.

Is it one usually used for cars? I've seen some in the $30 range and wondered if it would work on a camera...

[BAC]

I use a digital tachometer to check the speed of my Regular 8mm cameras.

Is it one usually used for cars? I've seen some in the $30 range and wondered if it would work on a camera...

No, it's a Digital Photo/Optical Tachometer like this:
http://www.coleparmer.com/Product/Extec ... Mgod_GkA4Q

I got mine for $15 on Ebay, just do a search for Digital Optical Tachometer.

[Will2]

I use a digital tachometer to check the speed of my Regular 8mm cameras.

Is it one usually used for cars? I've seen some in the $30 range and wondered if it would work on a camera...

No, it's a Digital Photo/Optical Tachometer like this:
http://www.coleparmer.com/Product/Extec ... Mgod_GkA4Q

I got mine for $15 on Ebay, just do a search for Digital Optical Tachometer.

That's what I meant...not a tachometer IN a car, ones used to measure timing by a mechanic...

[BAC]

The automotive ones I'm thinking of hooked up to the distributor cap and would flash every time that spark plug would fire. I'm sure they have something more high tech than that now, I stopped working on my engines when they put all that electronic crap under the hood. The one I have is used for measuring RPM on industrial machinery like a lathe. You put an adhesive foil on a shaft and the meter gets a reading of the RPM from that.

[kontrabass888]

I use a digital tachometer to check the speed of my Regular 8mm cameras. I remove the lens and load a test roll of film into the camera. The speed may be different when it has the resistance of the film plus the film is bright enough for the digital tachometer to detect. I point my digital tachometer at the shutter to get a reading. It gives me a reading in RPM which I convert to frames per second. 18 frames per second = 1080 RPM (18 x 60 = 1080). I also use it to check the turntable on my stereo. I just place a piece of foil on the turntable and let the digital tachometer read from that. I'm not sure how this would work with a Super 8 camera with a fixed lens.

In this way the tachometer will read the speed of the rotating shutter , so it even doesn't need to run a film,isn't it?

[BAC]

I use a digital tachometer to check the speed of my Regular 8mm cameras. I remove the lens and load a test roll of film into the camera. The speed may be different when it has the resistance of the film plus the film is bright enough for the digital tachometer to detect. I point my digital tachometer at the shutter to get a reading. It gives me a reading in RPM which I convert to frames per second. 18 frames per second = 1080 RPM (18 x 60 = 1080). I also use it to check the turntable on my stereo. I just place a piece of foil on the turntable and let the digital tachometer read from that. I'm not sure how this would work with a Super 8 camera with a fixed lens.

In this way the tachometer will read the speed of the rotating shutter , so it even doesn't need to run a film,isn't it?

The tachometer needs something bright to get a reading from, the film works for that. On my Bolex cameras the pressure plate is too dark. The camera also runs faster without film so you won't get an accurate reading. I use an old roll of Kodachrome which can be found very cheap.

[freddenacka]

I just use my zoom recorder. Make a test shot an record the sound from the camera.
Afterwords I knew exactly how many frames on exact time by the record.
I did try different things first without film but realized that tha camera was going slower in reall time with film.