Quote:
Originally Posted by andy153
..... it's not a subject I've ever studied
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Neither have I Andy. Never even truely tested top speed of 1/8,000 sec to freeze motion to understand its limitations.
Think of normal camera shutters and a series of blades ( 4 ) mechanically linked moving at 1/8,000 sec is no mean feat. To get that speed up to 1/30k or 1/50k to match the fastest burst from a flash requires a complete rethink of shutter design to reduce the number of moving parts.
Faster shutters are only of value if direct lighting is used. If flash is used then if exposure is for flash only, then flash duration becomes the key. Turning the power down does reduce the duration of the burst but also reduces the amount of light. That can be overcome by placing the flash closer to the subject.
Now you have two things affecting the overall exposure. Amount of light from the flash burst and ambient light recorded while the shutter is open. In a dark room with the shutter open there will be no ambient light so no image will be recorded. If you now fire a flash then an image will be recorded purely from the light generated by the flash. Flash duration will determine the ability of that burst of light to freeze motion.
In digital I guess the next consideration is amplification noise on long exposures. So a bit of experimentation is probably required here. For Lello's ballons then camera connected by a remote and you can probably get away with a few seconds. Trigger ... ( shutter open ) - Burst ballon ... ( flash fires ) - Shutter closes.
I have found a couple of further links that may be of interest.
http://chdk.wikia.com/wiki/Samples:_...r_&_Flash-Sync
http://www.woodselec.com/index.htm
Don