580 EXII Novice Needs Help

I have started using a flashgun for the first time and am trying to understand the details of fill-flash, balancing ambient light with flash etc. I believe that I have grasped the theory now but have a pretty basic question that I cannot work out for myself which is this.....

The guide that I am using states that (for instance) my exposure is 1/125 at f11 so I want to set the 580 EXII to f5.6 for two stops under. My question is how do I actually do that with the flash - the power is set in in fractions from 1/1, 1/2 down to 1/128 (as you know!) so how do you translate f5.6 to that scale...!?

I'd really be grateful for some help - in basic terms please...Thanks!

Welcome to the forums.

If there is no particular reason you are not using ETTL I would switch to ETTL, camera in manual mode, meter w/camera for one or two stops underexposed and let the flash fill for you. Balance the flash to ambient with FEC (flash exposure compensation).

If you definitely want the flash in manual mode the best I can suggest is get a flash meter, meter the ambient and adjust flash as desired.

And there are a lot more experienced folks here to help...but that's what I do.

james.spike wrote in post #6074542
I have started using a flashgun for the first time and am trying to understand the details of fill-flash, balancing ambient light with flash etc. I believe that I have grasped the theory now but have a pretty basic question that I cannot work out for myself which is this.....

The guide that I am using states that (for instance) my exposure is 1/125 at f11 so I want to set the 580 EXII to f5.6 for two stops under. My question is how do I actually do that with the flash - the power is set in in fractions from 1/1, 1/2 down to 1/128 (as you know!) so how do you translate f5.6 to that scale...!?

I'd really be grateful for some help - in basic terms please...Thanks!

As Dave said above, you might find it easier dealing with the flash in ETTL mode. However, if you have to use manual mode on the flash, then you'll need an incident light meter to determine what power gives you f/5.6. You have to adjust the flash output until the meter tells you it's at f/5.6.

james.spike wrote in post #6074542
The guide that I am using states that (for instance) my exposure is 1/125 at f11 so I want to set the 580 EXII to f5.6 for two stops under. My question is how do I actually do that with the flash - the power is set in in fractions from 1/1, 1/2 down to 1/128 (as you know!) so how do you translate f5.6 to that scale...!?

That guide was probably written for someone using the old "thyristor” type auto flash that can be set to auto expose for different f stops.

You really are better off to use ETTL (that's what you paid for).

BUT, if you still want to try it out as per your "guide", the 580EX II does have External Automatic Flash Exposure just like a Sunpak or Vivitar. Here is a link to a Canon tutorial. http://www.usa.canon.c​om …tArticleAct&art​icleID=946

Many thanks for the replies. ETTL it is then - I'd assumed that I had to use Manual Mode to have any kind of control - but as titus points out there is FEC to play with. I'm off to experiment.....cheers!

Manual mode with a light meter or trial and error work well, but so does ETTL and it's so much quicker.

Camera in M mode will give you more control and let the flash sort the exposure out. Remember, shutter speed has no impact on flash exposure so use it to get the ambient that you want.

Then remember that setting the FEC on the camera itself is the quickest way, but limited to +/- 2 steps on models less than the 1D.
On the flash itself you can set it to +/- 3 steps.