Andy,
An easy question. Remember that flash bulbs take a short time to ignite and
reach maximum intensity, and burn over a period of time. Smaller bulbs (MF
and M) might last 40 milliseconds, larger bulbs as used by the press might
last 60 milliseconds. Also the older between lens shutters take a short
time to fully open.
F synchronization, shutter released and electrical contact made
simultaneously. Intended for use with class MF and class M flashbulbs at
speeeds not faster than 1/40s. Most of the light is emitted while the
shutter is fully open.
M synchronization, the flash is fired 17 milliseconds before shutter
opened, to allow time for the flash intensity to build up before exposure
starts.
X synchronization fires the flash when the shutter is fully open. Suitable
for electronic flashes, which have a faster duration.
With the focal plane shutters the shutter needs to be fully open when the
flash fires, otherwise uneven exposure occurs. With these shutters the
electronic flash normally fires when the shutter is first fully open, which
meand if a slow shutter speed is used the movement of the image after the
flash is obtained. In some cameras there is an option for the electronic
flash to fire just before the shutter starts to closr (rear flash
synchronization), which means the movement in the subject leads up to the
flash exposed image, which looks better.
Good reference:- The Manual of Photography edited by Alan Horder Focal Press
sixth edition 1971.
Hope this helps.
JIm Thyer
----- Original Message -----
From: "ADavidhazy" <andpph@xxxxxxx>
To: "List for Photo/Imaging Educators - Professionals - Students"
<photoforum@xxxxxxxxxxxxxxxxxx>
Sent: Sunday, April 13, 2008 5:30 AM
Subject: Re: Hasselblad question
OK - did we cover "F" F, M, X and V
something to ponder ... by 60+ year olds.
andy
