Thanks for this post. I have same flashmeter in my bag but never figured how to use it. makes sense now.
Flash meter? What for? | 8.4.2009
Lately I have noticed increasing usage of flash meter in my photography as I have used it more than ever before. Part of the reason might be that I have finally got the grips with the meter and know how to actually use it. I have never been a histogram-type of a person for some reason and also I find it more systematic if I do lighting and camera setups based on numbers and not visual reference through camera's LCD screen. In the following I will try to explain how and why I use a flash meter, but certainly do not want to start another argument of Meter vs Historgam as seen on many discussion boards.
Lets take for example a photo shoot in a studio where I use white reflective umbrella as key light and another strobe acting as a hair light coming from behind the model hihh from above. I use flash meter in two following scenarios:
1. I want to use certain aperture, shutter speed and ISO and setup lights according to these.
or
2. I want to set flash powers and use these to setup aperture, shutter speed and ISO.
In my first scenario I want to use 1/60s shutter speed in order to allow as much ambient light in as possible and use aperture of f/4 to control my depth-of-field. I set ISO to 400. Because I know where I want to go from here it's easy to setup strobes by using a flash meter.
So I grab my good friend Sekonic L-308S flash meter from my backpack and set the ISO to 400 and shutter speed 1/60s on the meter. I have the meter on incident metering mode as I want to meter the light that falls onto the model and not the light that is reflected from the model. I then place the meter in front of the model's eyes with the white dome pointing toward the key light and trigger the flash with TEST-button on my radio transmitter. The flash goes off and the meter gets a reading of aperture f/8. Because the flash is two stops higher than my desired exposure, I now take the key light's power down by one stop and meter it again. Now the meter shows aperture as f/4 so I have perfect exposure on the key light.
Next we will have to meter the exposure on the hair light. You do it exactly as above until you get the desired exposure reading from the meter. The power of the strobe depends on what kind of effect you wish to accomplish. If you want to have a halo around the hairline you might want aperture of f/2.8 and if you wish to just slightly highlight the hair you might want f/5.6 for the flash exposure value. And again, when you take the reading of the hair light, place the meter next to your model's head pointing the white dome toward the hair light, not toward the camera. I will discuss this later why you should do this instead of pointing the dome toward the camera.
In my second scenario the difference is, that for reason or another you want specific strobe power to be used, lets say 1/1 and 1/2 power, and set your camera's settings accordingly. This type of scenario can be photography against backlight or you want to use 1/32 power to save your batteries.
In this case the procedure is done the opposite way as in the first scenario. First you deside what shutter speed to use (which you get from metering the ambient light) and set that into the flash meter. Take a reading of the key light and set that aperture and ISO reading into your camera.
By using a flash meter you can also get accurate flash ratios which is little difficult to do by looking at the histogram. For example, if you wish to have hair light one stop higher than the key light, all you have to do is take a meter of that flash and adjust it accordingly until your meter shows f-stop figure one stop higher than what you get from the key light.
The argument wether it's faster and more efficient to use a flash meter or histogram is a matter of photographer's own preference in my opinion. Both methods involve more or less trial-error steps. Over some experience you will automatically figure what settings to use and when, but until then or even after, the flash meter really is a handy tool.
Lets get back to the issue of where to point the white dome of the flash meter. In many sources it is mentioned that the flash meter's dome should be always pointed toward the camera and not the flash. Lets put this theory into test, shall we?
Lets say we have a studio setup with key light camera left at f/8 and fill light camera right at f/4. If you take a reading from the model's head toward the camera, you will get value of f/5.6 for the aperture. If the main light's power is set to translate to aperture value of f/8, then wouldn't the f/5.6 aperture overexpose the model's face? If you take a reading from the key light pointing the dome toward the flash and use that aperture for your exposure settings, the model's face will be exposed correctly and the fill flash does the fill as it should. No more, no less.
The most important thing to remember is to get beautiful and correctly balanced pictures no matter what tools you use. Flash meter is not the only one and correct tool for measuring light, but I for one have had nothing but positive experience with Sekonic L-308S flash meter even though it doesn't have the all pro features in it.
Here is a neat video on using the flash meter I found from YouTube:
Lately I have noticed increasing usage of flash meter in my photography as I have used it more than ever before. Part of the reason might be that I have finally got the grips with the meter and know how to actually use it. I have never been a histogram-type of a person for some reason and also I find it more systematic if I do lighting and camera setups based on numbers and not visual reference through camera's LCD screen. In the following I will try to explain how and why I use a flash meter, but certainly do not want to start another argument of Meter vs Historgam as seen on many discussion boards.