a bit of a problem with shutter speed

[adamwalsh]

May 17, 2008 at 11:07 am

Hello Pi

I was shooting two kids in a studio yesterday and they where running around and jumping . i had my camera in

manual
ISO = 100
f8
shutter speed 1/320

I upped the shutterspeed as there was more movement only to find that when i took a picture half the picture was fading to black, has anybody had this problem before, if so any advise.

Cheers

[Pitmatic]

May 17, 2008 at 11:47 am

what you are seeing is the shutter closing during the flashes exposure

Correct me if i am wrong anybody as i dont have studio lighting (wheres a sugar daddy/mummy when you need them!) but if you want to freeze the action with flash just leave the shutter speed alone and rely on the flashes duration to do the freezing.

I beleive that the more powerfull the flash the longer the duration so a lower power flash would be faster there might be some info about the flash speed in your manuals but your still proabbly talking about many thous of a sec anyway so shold freeze the fastest mover in the studio :)

This was done using a long exposure (10 secs) in a dark room and relying on a flash gun in a disposable camera to light the dice as they fell and bounced in the glass the flash had red eye so fired a couple of times making it look like i had many more dice than there really were.

[stcstc]

May 17, 2008 at 11:50 am

pitmac is right

you should shoot with your studio lights witha set shutter speed generally, i use between 125 and 250 of a second

[Ashley]

May 17, 2008 at 4:13 pm

adamwalsh wrote:

I upped the shutterspeed as there was more movement only to find that when i took a picture half the picture was fading to black, has anybody had this problem before, if so any advise.

Your camera flash sync is probably 1/250th, so you need to shoot at that speed or slower.
The Hasselblad H system sync is 1/800th.

You flash light will have a flash duration rating and depending on the make and model it could be anything from as slow as 1/300 to as fast as 1/12000 s or even faster.

Part of the reason why many photographers like using Profoto‘s, such as the Pro-7A 1200, is because of their very short flash durations (1/2200–1/12000 s) and their super-fast recycling times (0.08–0.7 s).

[GCP]

May 17, 2008 at 4:22 pm

The guys are right. 1/320 is too fast for a curtain shutter. My old Bronica would shoot at that speed as the shutter is a leaf type and it is in the lens as opposed to the camera. I think , if I remember from my teachibg days, that the leaf shutter will not give this effect ……. then I think most leaf shutters work at 1/500 max. The Hasselblad would also be a leaf type shutter in the lens. This makes the lens expensive as each time you buy a lens you are also paying fot a shutter … LOL

[Ashley]

May 17, 2008 at 5:08 pm

GCP wrote:

…then I think most leaf shutters work at 1/500 max. The Hasselblad would also be a leaf type shutter in the lens.

H System
The central lens shutters of the lenses add flexibility by allowing flash to be employed at shutter speeds up to 1/800s

or what about the Hy6
Leaf shutters with full flash sync up to 1/1000sec.

Who needs a car – just buy one of these instead :)

[Thorsten]

May 17, 2008 at 9:56 pm

If I’m not mistaken, nobody has yet explained to Adam why, when he increased his shutter speed above a certain value, half of his image faded to black. Adam, can I suggest that you take a look at this Understanding Flash Sync Speed article for starters. It clearly explains how your film or digital sensor is exposed by the opening of a shutter. Of course, no mechanical focal plane shutter has yet been made that is capable of travelling so fast that it can open and close fast enough to make an exposure using really high shutter speeds, so designers came up with an ingenious solution using two shutter blades instead of one. At high shutter speeds the second shutter blade starts to close before the first one is fully opened and it basically follows the first shutter blade so that what you have, in effect, is a slit of light travelling across your film or sensor. Now, throw a burst of flash at that and you’ll see that the flash is so fast that it only exposes one segment of the film or sensor before turning off again. So the only way for flash to expose the whole sensor is for the whole sensor to be open and that can only happen if the first shutter blade has completely opened before the second on starts to close. This will happen at any speed that at or below your maximum sync speed.

Hope I haven’t added to the confusion by now – let me know if I have.