Paul C. Buff, Inc. Technical Forum

I shoot alot of cheerleading competitions with my camera flash power pack combo, but with the einstein's action mode I was wondering at what distance would the strobes have to be to freeze the action. Because I'm no more than 2 feet from the mat at all times. I was thinking of a set up of two einstein's and two 11-inch long throw reflector's at either end of the mat.

At these distances . . . . even at 8-10', you should be able to shoot at 1/8 to 1/32 power and get good exposures in the 1/10,000 second t.1 range. Sliver PLM is a boon for getting very high output and wide coverage at very low power.

That is a tough question to answer absolutely. Peak action is easier to freeze than mid action. Also, are the tips of toes, fingers, hair critical? These tend to move faster than the cheerleaders, which are relatively easy to freeze on the whole. -1f (320Ws) will give you 1/2000 t.1 time. -2.2f (139Ws) will give you virtually 1/4000 t.1 time.

Given these numbers, how far away they have to be will then depend on a) thier power settings, b) the mdifier used, c) the other variables in exposure, such as desired/used aperture value as well as ISO.

Thanks paul that is very helpful. Yes their toes,hair face must be frozen as well. I shoot alot of sports so I relize that not everything will be in focus all the time, but I'll take 80% over my current 40% now. Are the plm's my only option or are the 11-inch long throws not an option? My iso is 400-1600 sometimes it depends on the arena I'm shooting in.

The PLMs are good because you get a lot of light on your subject, but still get wide coverage. The long throws are narrower in coverage. Again, this depends on the distance of the lights to subject as to how big the final "spot" of light will be. I agree the PLMs would be the better option (64" probably the best). Given your willingness to use higher ISO, you should not have a problem freezing action by reducing power, even if the lights are a few feet from the mat.

Taking Paul's example, 1/8 power (40Ws) will yeild about f/8 at 10' from the subject at ISO 100 and give you 1/10,000 t.1 times with a silver PLM. 14' will be about f/5.6 and 20' will be about f/4. Then, of course, for each stop of ISO you move up, you gain a stop in aperture.

Thanks you answered all my questions. You guys are the best!!

Assuming there are spectators at these events, it seems like they wouldn't be very happy about having a couple of 64" PLM's blocking their view. They're great modifiers, but they're not transparent :o

There are alot of people there, that's the only drawback to the plm's but the results will make them happy.