Cf-14 Automatic flash reduction

sonix · 27th December 2003

Hi All,

Do you have to turn this function off if you do manual compensation on your flash (550EX).

Will it still work if let's we have +1 for the flash but still have CF-14 still "enable"?

Thanks,
sonix

sonix · 30th December 2003

No one can answer?

clive · 30th December 2003

if cf14 is enabled and u set flash exposure compensation (FEC)to plus one then the resulting flash output wil be "reduced but plus one stop of brightness"

give some hypothetical numbers for example:

cf14 disabled and (FEC) set at +0. then flash output will give you like..say 150 units of brightness.

suppose every stop of FEC gives/takes away say 30 units of brightness.

cf14 enabled, (FEC) at +0: flash will give you say 80 units of brightness

cf14 enabled, (FEC) at +1: flash gives you 80+30 units of brightness

cf14 disabled, (FEC) at -2: flash gives you 150-30-30=90 units of brightness.

this is just a very simplemindedly rough way of understanding how this ETTL mechanism works. it is based on the assumption that the 2 effects of cf14 and FEC and distinct but additive. (oh no...reminds me of field theory

) of coz, u ca nalways expend a few shots to test it out n c 4 urself once n 4 all

CYRN · 2nd January 2004

I also understand that for 10D, some modes you still need to set the FEC on the 550 itself.

Do they, cf14 and 550 FEC "adds up"?

27th December 2003	#1
sonix Member Join Date: Jan 2002 Location: Sengkang Posts: 1,314	Cf-14 Automatic flash reduction Hi All, Do you have to turn this function off if you do manual compensation on your flash (550EX). Will it still work if let's we have +1 for the flash but still have CF-14 still "enable"? Thanks, sonix __________________ My humble gallery

30th December 2003	#2
sonix Member Join Date: Jan 2002 Location: Sengkang Posts: 1,314	No one can answer? __________________ My humble gallery

30th December 2003	#3
clive Senior Member Join Date: Oct 2002 Posts: 2,573	if cf14 is enabled and u set flash exposure compensation (FEC)to plus one then the resulting flash output wil be "reduced but plus one stop of brightness" give some hypothetical numbers for example: cf14 disabled and (FEC) set at +0. then flash output will give you like..say 150 units of brightness. suppose every stop of FEC gives/takes away say 30 units of brightness. cf14 enabled, (FEC) at +0: flash will give you say 80 units of brightness cf14 enabled, (FEC) at +1: flash gives you 80+30 units of brightness cf14 disabled, (FEC) at -2: flash gives you 150-30-30=90 units of brightness. this is just a very simplemindedly rough way of understanding how this ETTL mechanism works. it is based on the assumption that the 2 effects of cf14 and FEC and distinct but additive. (oh no...reminds me of field theory ) of coz, u ca nalways expend a few shots to test it out n c 4 urself once n 4 all Last edited by clive; 30th December 2003 at 04:51 PM.

2nd January 2004	#4
CYRN Senior Member Join Date: Nov 2002 Posts: 4,483	I also understand that for 10D, some modes you still need to set the FEC on the 550 itself. Do they, cf14 and 550 FEC "adds up"? __________________ Photoevangel - Gallery - Photography Evangelism : Spreading the Good photography.