Cockney wrote:
I have just started to use my 7D with studio flashes. In the hand book it says that the max sync speed is 250th but with the camera set at this speed there is noticeable dark section in the shot. This is caused by the shutter curtain not being fully open during flash. Changing the speed to 180th overcomes the problem. Has anyone noticed this on the 7D ? The difference in speed is considerable, the camera is quite old and well used so I'm wondering if this is something that can be fixed or should I just accept it. Any thoughts?
I have just started to use my 7D with studio flash... (
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Yes, I've noticed it... as has anyone who is using their focal plane shutter camera with studio strobes.
The strobes put out a lot more light than portable flash do, but they also are slower firing, take longer to reach peak output. So a slower sync speed is typically necessary with studio strobes, regardless of the camera model.
7D and other Canon that sync at 1/250 with portable flash will usually need to be reduced to 1/180 ir 1/160 with studio strobes.
5D-series, Rebel series that sync at 1/200 with portable flash likely will need to be slowed to 1/125 with studio strobes, sometimes 1/160 will work.
Old flash bulbs are even slower, often requiring 1/60, 1/30 or even 1/15 in some cases.
Some studio strobes are able to sync at higher speeds, but those are typically a lot more expensive (example, Profoto B1 500 watt second strobes which are available Canon ETTL compatible, can be used at the protrable flash sync speed - 1/250 on 7D - and are even able to do High Speed Sync up to 1/8000.... but cost $2100 apiece).
Leaf shutters that few camera today use allow for more flexibility syncing with flash and strobes, but are not able to shoot at the very high shutter speeds that focal plane cameras can use. Most DSLRs I'm aware of use focal plane shutters. Most medium format digital are FP too, but a there may be some leaf shutter lenses in some of those systems. Typical leaf shutter's top speed is 1/500, a few may be able to shoot 1/1000.
Electronic shutters are another matter. I'm really not sure how they sync with flash, but would guess that they have more flexibility. A few DSLRs are being offered with them now (often in conjunction with an electronic viewfinder).
Continuous light sources should be usable at almost any shutter speed. In the past these were referred to as "hot lights" for obvious reasons.... but now there are some interesting LED-based and fluorescent "cool lights" that might offer an alternative.