420ex bounce!!

Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

Thanks,

Joe

"joe" wrote in message
m...
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

Thanks,

Joe
Well Joe what do you know! Bouncing doubles the distance and as far as I can
remember the fall off in light intensity follows the inverse square law.
Your canon 420e should give maximum distances that the flash is effective.
Other than I dont know.

MikeS

"joe" wrote in message
m...
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

Thanks,

Joe
Well Joe what do you know! Bouncing doubles the distance and as far as I can
remember the fall off in light intensity follows the inverse square law.
Your canon 420e should give maximum distances that the flash is effective.
Other than I dont know.

MikeS

"joe" wrote in message
m...
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

Thanks,

Joe
Well Joe what do you know! Bouncing doubles the distance and as far as I can
remember the fall off in light intensity follows the inverse square law.
Your canon 420e should give maximum distances that the flash is effective.
Other than I dont know.

MikeS

"Gisle Hannemyr" wrote in message
...
(joe) writes:
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

The guide number for a 420ex when bounced is 34 (meters @ ISO 100).
Converting to feet, we get a GN of 111.

If you bounce, a rule of thumb is to calculate aperture from GN by
using twice the ceiling height, and then deduct 1-3 more stops
(depending on the colour and reflectivity of the ceiling: 1 if it is
clean, white, 2 for off-white, and 3 if it's cream). Just dividing
111/36 gives us 3 (~ f/2.8). One stop less is f/2, two stops less
is f/1.4.

I.e. its marginal - it may work at ISO 100 or not, depending on how
reflective the ceiling is and how fast lens you use. If you've got
a camera that allow you to use ISO 200 or 400 without adding too
much noise, your margin is better.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
================================================== ======================
«To live outside the law, you must be honest.» (Bob Dylan)

That's if it's flat, if it is a cathedral type ceiling, sloped, that changes
things a little. He'd be best off using an attached bounce IMHO.

--
Skip Middleton
http://www.shadowcatcherimagery.com

"Gisle Hannemyr" wrote in message
...
(joe) writes:
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

The guide number for a 420ex when bounced is 34 (meters @ ISO 100).
Converting to feet, we get a GN of 111.

If you bounce, a rule of thumb is to calculate aperture from GN by
using twice the ceiling height, and then deduct 1-3 more stops
(depending on the colour and reflectivity of the ceiling: 1 if it is
clean, white, 2 for off-white, and 3 if it's cream). Just dividing
111/36 gives us 3 (~ f/2.8). One stop less is f/2, two stops less
is f/1.4.

I.e. its marginal - it may work at ISO 100 or not, depending on how
reflective the ceiling is and how fast lens you use. If you've got
a camera that allow you to use ISO 200 or 400 without adding too
much noise, your margin is better.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
================================================== ======================
«To live outside the law, you must be honest.» (Bob Dylan)

That's if it's flat, if it is a cathedral type ceiling, sloped, that changes
things a little. He'd be best off using an attached bounce IMHO.

--
Skip Middleton
http://www.shadowcatcherimagery.com

"Gisle Hannemyr" wrote in message
...
(joe) writes:
Can anyone tell me if an 18 foot high ceiling is too high for bounce
flash using the canon 420ex.

The guide number for a 420ex when bounced is 34 (meters @ ISO 100).
Converting to feet, we get a GN of 111.

If you bounce, a rule of thumb is to calculate aperture from GN by
using twice the ceiling height, and then deduct 1-3 more stops
(depending on the colour and reflectivity of the ceiling: 1 if it is
clean, white, 2 for off-white, and 3 if it's cream). Just dividing
111/36 gives us 3 (~ f/2.8). One stop less is f/2, two stops less
is f/1.4.

I.e. its marginal - it may work at ISO 100 or not, depending on how
reflective the ceiling is and how fast lens you use. If you've got
a camera that allow you to use ISO 200 or 400 without adding too
much noise, your margin is better.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
================================================== ======================
«To live outside the law, you must be honest.» (Bob Dylan)

That's if it's flat, if it is a cathedral type ceiling, sloped, that changes
things a little. He'd be best off using an attached bounce IMHO.

--
Skip Middleton
http://www.shadowcatcherimagery.com