How do you use a gray card for proper exposure?
First of all, your shutter speed doesn't affect flash exposure like it does with ambient light. Flash control is based on the aperture (f/stop) setting alone. Your shutter speed needs to be at the camera's sync speed, or below.
Have someone hold the card in front of their face (the same distance from the light is important) and get close enough to fill the frame with it. Fire the strobe (or flash) and look at the camera's histogram. You should have a "spike" near the middle of the histogram (very slightly left is OK).
If the spike is to the right of center, stop the lens down, and if it's to the left, open it some.
You can also adjust the power setting of the light (or the light-to-subject distance).
Matthew
Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"
MLKstudios wrote: It is possible to use an 18% card for flash exposure using some trial and error.
First of all, your shutter speed doesn't affect flash exposure like it does with ambient light. Flash control is based on the aperture (f/stop) setting alone. Your shutter speed needs to be at the camera's sync speed, or below.
Have someone hold the card in front of their face (the same distance from the light is important) and get close enough to fill the frame with it. Fire the strobe (or flash) and look at the camera's histogram. You should have a "spike" near the middle of the histogram (very slightly left is OK).
If the spike is to the right of center, stop the lens down, and if it's to the left, open it some.
You can also adjust the power setting of the light (or the light-to-subject distance).
Matthew
Good to know. Thank you, Mathew.
What week is this covered in?
“Amateurs worry about equipment, professionals worry about money, masters worry about light, I just make pictures… ” ~ Vernon Trent
HP, I cover guide numbers too, but today many people add an umbrella or softbox (Wescott makes a few for flashes now) or some other kind of diffuser. They throw the guide numbers out the window. But I agree, the GN of your flash is very important to know.
BTW not all companies are using ISO 100 anymore. It rates better at ISO 200. Marketing.
Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"
Later, they realized the color was neutral enough to be used for white balance too, and were able to ride the digital wave.
They're expensive, and many like them. However, you can get as good or better WB and exposure using cheaper tools. A KODAK (or Delta) brand gray card for exposure and a Robin Myers Imaging or similar for white balance will cost about $25 USD.
I also make my own dual purpose cards based on the RMI card. I paint one side of it 18% gray so it can be used for both -- exposure and white balance.
Matthew
Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"
When using a flash/strobe with an Expodisc (or a gray card for that matter) to set proper exposure, I have to take the extra steps to check the histogram after taking a shot, make adjustment to my exposure setting, take another shot, check the histogram again and so on until I nail the correct exposure. It's essentially chimping with a highly accurate histogram instead of a less reliable LCD screen.
This is where I think a handheld flash meter has its advantage when shooting with a flash, because once you sync the ISO and shutter speed between the camera and the flash meter, it will tell you the EXACT aperture to use to get a correct exposure. Take a flash metering, set the aperture on the camera, take a shot, and you're done.
I watched the video lesson from Expodisc's website in which the presenter was teaching the viewer how to use it in a studio setting to get proper exposure. However, he used a hot strobe for continuous lighting. What I wanted to see instead is how it could be used with flash units. I think more people use flash units than continuous lighting.
I've never used a flash meter or an Expodisc to set proper exposure, so please correct me if anything I said is not right. Thanks.
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