Archived posting to the Leica Users Group, 2003/08/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]You don't even have to use film. The flash will illuminate the position of the marble and you or your friend will be able to mark how far it has dropped on the meter stick. Repeat the test a number of times and discard all readings less than 15 cm. You are obviously jumping the gun. This simple test is about as accurate as they come. Larry wrote: <<Here is how to measure your own total lag time (human plus camera). Set up a meterstick against a wall. Have a friend hold a small object, say a black marble, at the top of the meterstick. Focus your flash equipped camera on the stick. Now tell your friend to drop the marble at any time during the next few seconds but not to give you any indication of when it will be dropped. When you see the marble start to move, snap the shutter. Repeat the process at least half a dozen times. Now look at the prints (or just the negatives through a magnifying glass). Using the equations we learned in high school physics we know that the distance the ball will fall in a given time is: distance = 1/2 a * t^2 where distance is measured in centimeters, a is the acceleration due to gravity and is equal to 980 cm/sec/sec t is time in seconds. This equation can be rewritten as: time = sq. rt. (distance/490) If the average distance the ball travels is 20 cm, the total latency is 202 milliseconds. If the average distance is 30 cm, the latency is 247 milliseconds If the distance is 40 cm, the latency 286 milliseconds And 50 cm = 319 ms.; 60 cm = 350 ms.; 70 cm = 378 ms.; 80 cm = 404 ms.; 90 cm = 429 ms.; 100 cm = 452 ms. If the ball bounces off the floor before the camera clicks, either get a new camera or forgoe sports photography. You will miss too many pictures.>> - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html