F2.8 vs F4 flash photos

[alvin]

With a flash in low light situation (wedding dinner example. i am NOT wedding photographer), will a f2.8 lens achieve brighter background?

My setup is Dynax 5, Press 800, minolta 70-200/4, Metz 32Mz2, exposure usually F4 1/125s or F4 1/90s. Flash set on TTL, direct flash, no bounce. Mostly firing at the 200mm range (far far away from the B&G.) Previous tests with 1/60, 1/30 got some handshake....

 

[tweakmax]

With a flash in low light situation (wedding dinner example. i am NOT wedding photographer), will a f2.8 lens achieve brighter background?

My setup is Dynax 5, Press 800, minolta 70-200/4, Metz 32Mz2, exposure usually F4 1/125s or F4 1/90s. Flash set on TTL, direct flash, no bounce. Mostly firing at the 200mm range (far far away from the B&G.) Previous tests with 1/60, 1/30 got some handshake....

Yes but the picture will not be sharp

 

[binbeto]

With a larger aperture or a slower shutter speed, you will achieve a brighter background.

ie. F4 -> F1.8
ie. 1/125s -> 1/60

With aperture being bigger, your dof will be narrower.
With shutter speed being slower, motion blur and camera shake might be a problem.

If you are using TTL flash, the recycle time will be lesser too.

I dun really get what tweakmax means by the pic will not be sharp. Perhaps he is assuming the lens will not be sharp at wide open. Some better lens have pretty decent sharpness even if wide open. At least it would show much in a 4R print.

 

[tweakmax]

With a larger aperture or a slower shutter speed, you will achieve a brighter background.

ie. F4 -> F1.8
ie. 1/125s -> 1/60

With aperture being bigger, your dof will be narrower.
With shutter speed being slower, motion blur and camera shake might be a problem.

If you are using TTL flash, the recycle time will be lesser too.

I dun really get what tweakmax means by the pic will not be sharp. Perhaps he is assuming the lens will not be sharp at wide open. Some better lens have pretty decent sharpness even if wide open. At least it would show much in a 4R print.

yup this is what i mean...

 

[alvin]

Thanks dudes! :thumbsup: