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- Name
- Carl
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Hello everybody, I’m trying to get my head around shooting with a flash as I’m generally a landscape shooter so flash is something I’ve had very little experience of! I think I’m finally getting somewhere and I just want to check if my understanding is in the right area.
Say I’m shooting a portrait of someone outside. I want a reasonable DoF so I’m shooting at f/8. I meter the background and it tells me the correct exposure for f/8 at ISO 400 is 1/250 sec. Am I right in saying (I hope so, because this will be a lightbulb moment for me!) that I set my camera at f/8 and 1/250, using ISO 400, which correctly exposes the background, and then change only the flash power to correctly expose the subject?
To expose the subject I’m using a flash which has a guide number of 141ft. My subject is at 9 feet from me, giving me an aperture to use of f/16. To get back up to my f/8 do I just half the power of the flash for each stop that I up? I.e GN of 141 = 1/1 power at f/16 or 1/4 power at f/8? This is of course for ISO 100, so my actual power to use is 1/32 for ISO 400?
If I’m totally wrong, any guidance or help is appreciated!
I have a few more questions afterwards, but I think it’s best to get my head round the basic bit first
Many thanks,
Carl
Say I’m shooting a portrait of someone outside. I want a reasonable DoF so I’m shooting at f/8. I meter the background and it tells me the correct exposure for f/8 at ISO 400 is 1/250 sec. Am I right in saying (I hope so, because this will be a lightbulb moment for me!) that I set my camera at f/8 and 1/250, using ISO 400, which correctly exposes the background, and then change only the flash power to correctly expose the subject?
To expose the subject I’m using a flash which has a guide number of 141ft. My subject is at 9 feet from me, giving me an aperture to use of f/16. To get back up to my f/8 do I just half the power of the flash for each stop that I up? I.e GN of 141 = 1/1 power at f/16 or 1/4 power at f/8? This is of course for ISO 100, so my actual power to use is 1/32 for ISO 400?
If I’m totally wrong, any guidance or help is appreciated!
I have a few more questions afterwards, but I think it’s best to get my head round the basic bit first
Many thanks,
Carl