how to input the light meter flash reading?

Chrisly2009

Chrisly2009

Suspended / Banned
Messages
49
Name
Chris
Edit My Images
Yes
Hi guys
I'm trying to mix ambient light with flash on a human subject to get an overall pleasing look.

So I have the sekonic l308s light meter set to ISO 400 and shutter at 1/4 sec which brings up 5.6. I dial this into my canon 20d and wallah.....a perfect ambient reading. Next I use my canon 580ex flash off camera through an umbrella.

I set the light meter to measure flash under the same ISO and shutter settings and fire the flash.
The reading records 16.

Now I get confused. What should the 580ex be on? Ettl or manual firstly?
Secondly what is 16 and how do you input it into a flash?

I also don't understand what the .1 or .7 e.g. the reading of 16.7 etc. How is this input to my 580ex?
 
I believe your 580 should be on Manual - initially set ISO at 200 and it should be set for flash - not ambient. Fire the flash with the dome of the light metre pointed at the camera from the position of the subject with the camera on Manual - ISA 100 and speed 1/125th. The metre will give you the correct readings to set your camera. You don't input into the flash after the first reading, it's the camera settings that you need to alter
 
Last edited:
If your ambient settings are giving you a correct exposure than adding more light from the flash is likely to cause overexposure of the subject, unless your subject is more dimly lit than the background.

The 16 shown by the meter means that you need to stop down from f/5.6 to f/16 to compensate for the extra light from the flash. If you do stop down then your background is going to get darker, and if it is far from the flash it will get 3 stops darker - the difference between f/5.6 and f/16.

16.7 means 16 and 7 tenths, which is about 16 2/3, which is f/20. You do not input these figures to the flash. You set the flash to manual and you adjust the power output from the flash so that you get the balance of light you require between ambient and flash If the flash is too bright by 3 stops, for example, then drop the flash power manually by -3 stops, which is to 1/8 power. If you want to drop the flash power by 3 2/3 stops then dial in 1/8 -0.7 on the flash. Then meter again to check everything is correct. Of course you could change the aperture instead, perhaps to f/11 and only need to drop the flash power to 1/2 (or 1/2 - 0.7 depending on what the meter was saying) and then reduce shutter speed to pull in more ambient for the background. There are many other combinations which would work in this scenario. The choice is yours.

I can't think of any benefit from using a hand held flash meter if you have the flash in ETTL mode. The flash will do whatever it wants to. Metering it won't accomplish anything. You need the flash to be in manual mode, putting you in control.
 
thankyou for taking the time to answer my question in depth. really appreciate that.
 
Interesting videos thanks John
 
Np I there's some good info in them . It convinced me to by a flash meter .
 
You must log in or register to reply here.
Back
Top