Jos from Holland wrote: > > > Not fully right Tom, your statement is only correct for a shiny surface, in > that case every part of the reflector (the ceiling) is directing the light > in the same way. But a perfect non-shiny (I do not know the right word in > english: difuse?)surface will reflect over 180 degrees with the same > intensity in all directions. If your approach works in practise, that could > be due to the presence of reflective walls that guide a part of the lost > light to the subject. Some tests in the dark outside would confirm this. > Greetings, Jos
I'll take your word for it. I've got at least 2 books that say to do the calculation that way, so I'm at a loss to explain it. It does seem to work, at least with neg film. Here's an online reference: http://www.photographytips.com/page.cfm/280 but Kodak says: http://www.kodak.com/global/en/consumer/pictureTaking/flash/flasPho9.shtml Quoted: "To determine exposure for bounce flash manually, first find the total distance from the flash to the bounce surface and from the bounce surface to your subject. Find the aperture that corresponds to this distance on the flash calculator dial; then set an aperture 1 1/2 to 2 stops larger than the aperture on the dial. For example, if the dial recommends f/8, use f/4. " I bet If I go back and look at the negs where I did this manually, they're underexposed but printable. Or maybe I was conservative...anyway, good catch. tv - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
