Understanding Hi Speed Sync

[MOmilkman]

I have the principles down for the most part, however there's one aspect I'm still hazy about.

At the bottom of this article direct from Canon, it states that using AE Priority is a recommended way to use High Speed Sync. However, if you set your lens to 2.8 (in my case) and have a low ISO in a dimly lit room then I might only get a shutter speed of 1/30 or 1/60 thus defeating HSS. Are they talking about using it only in a situation where you might be outdoors in direct sunlight? If you don't increase your ISO considerably then your never going to reach shutter speeds high enough to use HSS.

Thoughts?

[inkista]

They're basically just saying that green box auto or P mode will do fill flash for you, not so much that you have to be in those modes to do HSS.

Exposure is still exposure and about capturing light. If you're at a low ISO in a dimly lit room, it's going to be hard to get a fast shutter speed. You can go into Manual mode and force a high shutter speed, but your flash isn't going to light a whole heckuva lot of that room. It'll blast your subject, though, so if you want a black background that's one way to go.

You also have to understand that HSS severely reduces your flash's power output, because it has to make a series of timed bursts, rather than letting all the power go in a single burst. The faster your shutter speed, the more bursts it has to make, and the less power it can release for each one, so you have to help it out in other ways. One of those is shooting in daylight, and using the flash just for fill. Others would be jacking up the ISO or shooting at a very wide aperture.

But when you're asking a flash to illuminate a scene at HSS, in the dark, with a low iso, and a very fast shutter speed--you're probably running out aperture. There are limits to what a flash with only four AA batteries can light up.

[MOmilkman]

Thanks for laying that out for me. I've seen that link you provided before buy I need to read though it again as it breaks it all down very well. So thanks for providing that.

So I suppose HSS is more suited for brightly lit subjects vs dim lighting. Thanks inkista