checking speed projector

setori2 · Post by **setori2** » Sat Mar 20, 2004 1:53 pm

hi,
I want to check at what speed my projector EXACTLY run. I look for a frequencymeter with optoelectronic sensor (captor?) able to see the light projected on the screen and display : 24 fps, 25 fps etc. Does that exist ?

Philippe

Post by **schematic2** » Sun Mar 21, 2004 12:28 am

yes it does exist. Thats how I adjust projector speed. Most industrial suppliers have them. You just put a small amount of reflective tape on a shutter and point at it with the meter led.

They are often referred to as a photo tach....

Post by **Basstruc** » Sun Mar 21, 2004 3:13 am

A simple microphone connected to your soundcard could do the job.
Matt

Post by **setori** » Sun Mar 21, 2004 5:34 pm

yes, i know i can use a microphone, but i want too use this machine to check my cameras. Fot that, sound is not enough. I need an optical system.

Philippe

Post by **Pedro** » Wed Mar 24, 2004 11:01 am

There are optical measurement instruments to check the flicker of computer monitors. You simply point them towards the monitor and the flicker frequency is going to be displayed.
I think this would work for projectors, too. The value that is going to be displayed is 3x24 Hz = 72 Hz or 3x18 Hz = 54 Hz, when the projector has a 3-bladed shutter.
One model I have seen is called SCREEN-CHECK 2000 and costs about Ã¢â€šÂ¬ 10. Look at http://www.conrad.de (German) or http://www.conrad.com (other languages) and search for article number 128201-41

However, the total accurancy of that low-frequency measurements is not enough to assure sound sync, it is only good to adjust the pitch of the magnetic sound to a correct value.

Pedro

Post by **jessh** » Wed Mar 24, 2004 9:33 pm

if your projector or camera has a flash socket or similar once per frame contact it makes things a lot easier. Many High end multi meters have a function that will tell you the frequency that is being generated by it.....