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View Full Version : Just need to confirm my thinking:::



andylo
09-11-2010, 12:16pm
If I am stacking 2 x flashlights together...

I did NOT extended it's effective distance.

I ONLY double amount of light illuminate to my subject. (Which means my subject is 2 x brighter)

Looking forward to you answer :)

Wayne
09-11-2010, 12:21pm
Yes, assuming both lights are =

andylo
09-11-2010, 12:23pm
Yep, same setting everything. Same model of light too.

ameerat42
09-11-2010, 8:46pm
And, if they are of equal output, your exposure is increased by only 1 f-stop, though... Am.

andylo
10-11-2010, 10:50am
Oh! really? Damn, I thought it's more than that :(

ameerat42
10-11-2010, 6:27pm
Nope! N times the light/area of glass/aperture = sqrt of N increase in exposure. (This is the BRIGHT side, if you had 3 equival flashes you'd only 1.7 times the exposure. So you'd need 4 equiv flashes to get an increase of 2 f-stops.) Inverse square law for light intensity.
Am.

Longshots
13-11-2010, 10:00am
very useful response Ameerat42 :)