the canon 1DS II does only sync to studio flash untis on max 1/250 sec.
is there a way to increase the sync.
i need a higher syn i.e 1/500 or higher..
what do other people use for i.e action/ sports images shot in studio with flash units?
generally speaking you can only fire the flash when the shutter is fully open. The shutter consists of two sheets of material - the first leaf covers the sensor before the shutter is released. As the shutter is released this first leaf uncovers the sensor enabling exposure to commence. A set time later the second leaf travels across the sensor to cover it again and stop the exposure. For Canon cameras (except the 1D which has a slightly different mechanism) the second leaf will start to cover the sensor at most 1/250th of a second after the first leaf has fully revealed the sensor - this sets the maximum flahs synchronisation speed. For faster shutter speeds i.e. 1/1000th of a second the second leaf will start covering the sensor before the first leaf has fully revealed it, so you will in effect have a travelling slit revealing parts of the sensor as both leaves travel across the face of the sensor. Therefore, to ensure that the entire sensor is exposed and not just a slits worth you can only use flash below 1/250th second.
If you want to go faster then you will have to use very high power tungsten lighting with a continuous light output and use the same exposure techniques as per daylight photography. Shorter flash durations will not help as the shutter is not fully open above 1/250th second when the flash fires.
- This is wrong (brain was obviously in neutral until I read POMs post)
Another technique is to work in a dark room, open the shutter on bulb setting and then fire the flash at an opportune time. This will give you a shutter speed equivalent to the flash duration.
Medium or large format cameras will probably not help as the delay between the leafs of the shutter being fully open is probably less than 35mm as the travel of the shutter and their mass is greater than for 35mm - though you will need to check the specification of each camera to find out what they can do for you.