High Speed Sync

[asnow]

I have a Canon XSi (EOS 450D) and a 320ex flash. I have a question on high speed sync.

If for example I am doing fill flash on a bright day. Say I set the f stop to 2.8, the speed required for a proper exposure would be higher than the 1/200 sync speed. Because the 320ex flash supports high speed sync, will it automatically change to high speed sync mode when the speed goes faster than 1/200 (i.e. I don't have to do anything in the camera itself). Or do I have to go through the settings in the camera (it is buried way down in the menus so it is a pain to change it quickly) for the flash to actually use high speed sync.

[Richard]

If it's anything like the 580EX or 430EX you will have to enable it for it to function. The camera probably won't let you select a faster shutter speed until it is enabled...

[Marko]

Once it's enabled, it should always work until you disable it again.

[asnow]

Richard/Marko - you are right. Mind you I didn't doubt you. Just to prove it, I did a quick test and the camera limits the speed at 1/200. It is not until you set the high speed sync on the camera that you can go faster than 1/200. I noticed that on some bodies there is a button to set high speed sync (much faster). On the Rebel it is a pain. You have to go down through the menus to set it (and remove it).

I had been reading some articles on fill flash/high speed sync and one of then was confusing. It seemed to suggest that the flash would automatically go to high speed sync if the flash supported it. Obviously not. To be fair they didn't say that directly, that's the way I interpreted it.

[jerry kraus]

Page 28 of the instruction manual for the Canon 320EX Speedlight tells you that it will stay set for FP HSS until you change it back to 1st Curtain (Front) or to 2nd curtain (Rear) sync. Same way if you are using a Nikon, only they refer to it as Auto FP.