Second-Curtain Flash - What's The Best Setup For Me?

[68lbs]

Ok, hope this is ok, but thought best to have a separate thread for this following on from here.

I'm really keen on trying this 'dragging the shutter' thing, and 2nd-curtain flash. So I've been having a play in the living room here.

My equipment, if it makes any odds, is Canon 5D I with Canon 580EX II flash on the hotshoe.

I've had the camera on manual, using partial metering (big blob in the centre) to roughly under-expose the background by maybe 1.3 to 2 stops. The flash is then set to fire 2nd-curtain using ETTL to determine power. This seems to work ok, and give me the results I expect (blurry movement with subject 'frozen' in focus). However, when I move towards the window, or into different light, the results can become less good. Presumably because I am no longer using enough ambient light.

So...

I have done a test putting the camera in TV (shutter priority), setting metering to evaluative, and exposure compensation to -2 stops. I then set the flash to fire on 2nd-curtain, using ETTL to determine power.

This appears to work, but I wanted to check with someone 'in the know'.

Am I right that ambient light will be used to expose 2 stops under and flash will be used to bring the exposure upto 'correct as metered'. So if the subject is a bit over exposed I could dial in flash compensation on the flash to -1/3 etc?

Does this make sense to you lighting experts?

Am I correct in my thinking?

 

[dazzajl]

Am I correct in my thinking?

I think you are but I never use flash outside of manual, it makes my head hurt.

I've always taken the old fashioned (and to me, simpler) approach of having everything on manual, then using the shutter to control the ambient light and the aperture/flash power to control the flash. Then the only thing I really need to remember is that if I close the lens down a stop, to darken the flash, I need to double my shutter time if I want the ambient to stay where it was.

As with all these things, after a while of playing about, you'll find the way taht suits you.

 

[DavePaliwoda]

According to Joe McNally's latest book (And I'm not sure whether this applies to Canons as well as just Nikons), the cameras exposure comp is the main over-ride; If your camera is two stops under and your flash is on normal exposure, the photo will be two stops under.


However, if you set your camera to -2, and your flash to +2, it may not necessarily give you an adjusted exposure.