flash metering...


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Gunjack

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Jul 6, 2002
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Let's say I get an ambient reading on a flash meter of 1/60 sec at F5.6. And then I use a test flash reading on the subject to give an aperture of F5.6 too. Will the subject be overexposed due to the flash + ambient light? How do you get the flash to ambient light ratio?
 

Gunjack said:
Let's say I get an ambient reading on a flash meter of 1/60 sec at F5.6. And then I use a test flash reading on the subject to give an aperture of F5.6 too. Will the subject be overexposed due to the flash + ambient light? How do you get the flash to ambient light ratio?

If you want to reduce ambient light, you can increase the shutter speed. Ambient light is controlled by both shutter speed (up to a certain point) and aperature so at 1/60 f/5.6, the flash would act as a fill-in (and not double the amount of light).
 

It should not be overexposed. I assumed that the flash was meant to act as a fill-in. The background should be well exposed if your ambience metering is accurate. Subject should also be well exposed as your fill-in flash was set at same f-stop as your ambience. This is the theortical aspect.

In practice, your pix should be well exposed, however, you may find the fill-in flash too strong, thus 'artificial' looking. Ideally, the fill-in flash should be enough to 'light up' the subject yet look natural. To get it right, you will need to experiment.

I do not understand about your 'ratio'.
 

if u are using Minolta meters,it will show u the ratio of flash to ambient.The flash meter will show in units of 10, while the auto meter will show 25%,50%,75%,100%. Go to Minolta showroom for the light meter catalogue,there are examples there.

Higher end Sekonic also has this function, but not the polaris one
 

Thanks guys, especially xfathom69 for the minolta showroom tip!
 

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