hi i am a newguy in photography. i own a canon eos 50 (ELAN II) and 420 ex speedlite for the fp mode wjhereby flash speed can be above 125, but what's the difference between 125, 250, 500,1000 and above? thanx

-- luic (luicbee@hotmail.com), May 14, 2001

Answers

Shutter speeds faster than 1/125th are useful for shooting with larger (numerically small) apertures. f/2, f/1.4, f/1.0. The larger the aperture, the faster the shutter speed must be to prevent too much light from hitting the film. Conversely, the smaller the aperture (larger numerically), the longer your shutter speed has to be to properly expose the film.

In regards to FP flash, it's the same principle. If you desire less depth of field that a "fast" lens offers, and are shooting outside, you need FP flash mode to increase the shutter speed. In the old days, most cameras only did flash sync at 1/60 or slower. If you were shooting 100 ASA and were in direct sunlight, your aperture would have to be f/22 to achieve proper exposure. Few flashes had enough power to have any kind of reach at f/22. Now with FP flash, you can use 100 ASA, and shoot at f/4 in full sunlight and your shutter speed will only go to 1/1000th. FP mode is great for shooting in daylight conditions. Your depth of field is now controllable. Plus your flash does not have to fire at full power every time. f/4 is easy for the flash to do.

-- Colin Miller (ckmiller@pond.net), May 15, 2001.