16 x 16 / 10 = 25.6
Square root of 25.6=f/5 (rounded off)
Or suppose you are at f/8 and you want 4 times more light.
8x8 (or 8 squared) / 4 = 16
Square root of 16 = f/4
We are just talking about the area of the aperture, right?
No logs!
--
Kim Mosley
mrkimmosley@xxxxxxxxx
Website: http://kimmosley.com
Blog: http://kimmosley.com/blog
On Thu, Jan 20, 2011 at 8:31 PM, ADavidhazy <andpph@xxxxxxx> wrote:
I was intrigued by a statement I made during a review of a sample exam
session and this afternoon decided to find out what the new f# should
be given that one wants to increase the light level at the image plane
over that available at some starting f#. After 4 hours of pondering
came up with this (whole increments would be quite easy ...):
http://www.davidhazy.org/andpph/text-fnumber-aperture-adjustment.html
I am sure there are easier ways to do this and if so a hint would be
most welcome! Of course fractional or "decimal" f#s are not easy to set!
Andy
--
Kim Mosley
mrkimmosley@xxxxxxxxx
Website: http://kimmosley.com
Blog: http://kimmosley.com/blog
