In article MY1Mi.31054$x%6.30938@pd7urf2no,
"jim wilson" wrote:

"Dave Moorman" wrote in message
]...
In article
,
Grumpy AuContraire wrote:


The F16 rule is ASA speed equal shutter speed @ F16 in bright daylight.
Experience dictates variables from that point. Cloud cuts off the sun,
drop to F8 etc.

Is the other part of that rule of thumb that you set the exposure time
for 1/the lens length? I.e., if you're using a 75mm lens, set the
exposure time 1/75 (or as close as you can get).
Sorry I never heard that one-the focal length by itself has nothing to do
with exposure, only the lens aperature. F16 on any lens passes the same
amount of light.
jim

Yes, but no. F/16 with the shutter open for 1/50th of a second passes
five times the light of F/16 with shutter open for 1/250th of a second.


If you're going to avoid over- or under-exposure, you have to set both
the aperture and the exposure time to the right settings.

Dave