Donald Miller said:Since most use light meters to determine exposure, it is probably not information that is published.
Fred Picker (founder of Zone VI) used a system called the Key Day system. A variation of the Sunny F 16 rule. His system went like this. If there were no clouds...bright sunlight then F16 or equivalent EV was the exposure for the day. For a light overcast day open a stop. For heavy overcast open another stop. For open shade open another stop. For deep shade open another stop.
His system was based on the fact that Edward Weston, so far as I know, never used a light meter and made some incredible images. It is entirely possible to learn to read light without the benefit of a meter. In fact I think that many would benefit from learning the practice for those times that a meter is unavailable (Ansel Adams' Moonrise over Hernendez) or when the batteries shoot craps.
Good luck I hope that this helps.
photobum said:Has everyone forgotten about the Kodak pocket photoguide? There was also the little Master photoguide and the bigger Professional photoguide. All three had an existing light exposure dial that covered everything from skyline at sunset to fireworks to Niagara falls under dark lights. The pro guide even has moonlighted landscapes. I don't leave home without one.
Do these digital imaging stores have these anymore? I know you can fine one at the photo shows.
Rhys you may be stepping on some Kodak copyrighted toes here. Watch out.
If you need an answer to a specific problem, give me a PM. I'll give you the Kodak answer. They were real good once.
Donald Miller said:Since most use light meters to determine exposure, it is probably not information that is published.
Fred Picker (founder of Zone VI) used a system called the Key Day system. A variation of the Sunny F 16 rule. His system went like this. If there were no clouds...bright sunlight then F16 or equivalent EV was the exposure for the day. For a light overcast day open a stop. For heavy overcast open another stop. For open shade open another stop. For deep shade open another stop.
rhys said:. . . There are formulae around to calculate Lunar and Solar positions at various times in the year. I must find out about that next :d
Donald Miller said:. . . Edward Weston, so far as I know, never used a light meter and made some incredible images.
BradS said:ah, but....this is exactly the Sunny 16 rule.
Stephen Benskin said:Loyd Jones and H.R. Condit wrote a paper for the Journal of the Optical Society of America in 1948 titled Sunlight and Skylight as Determinants of Photographic Exposure. It was published in two parts and combined is about 80 pages. It would not be an exageration to say this is the ultimate source for everything discussed on this thread. In addition, I don't think it's a coincidence that the first ASA standard of light meters was also release the same year this paper was published and that Jones was the chair on the light meter committee.
On the subject of light meters, the basic balanced exposure equation is:
A^2/T = BxS/K
where
A= aperture
T = shutter
B = luminance in footlambarts
S = film speed
K = constant
Here's the Sunny 16 example
16/ 1/125 = 297x125 / 1.16
this reduces down to
256/256 = 1
Donald Miller said:Stephen,
Where would one find the paper that you mentioned? Thanks for sharing this information.
Dave Miller said:Ed Buffaloe has a article on this subject that may assist.
http://unblinkingeye.com/Articles/Exposure/exposure.html
Stephen Benskin said:Don,
Jones, L.A. and Condit, H.R., Sunlight and Skylight as Determinants of Photographic Exposure. I. Luminous Density as Determined by Solar Altitude and Atmospheric Conditions, JOSA, vol. 38, #2, Feb 1948.
and
Jones, L.A. and Condit, H.R., Sunlight and Skylight as Determinants of Photographic Exposure. II. Scene Structure, Directional Index, Photographic Efficiency of Daylight, Safety Factors, and Evaluation of Camera Exposure, JOSA, vol 39, #1, Feb 1949.
I got mine at UCLA in their science stacks. Any good size university should have it. If you don't have access, The Optical Society of America will make copies for you. It's expensive though. Even with gas prices where they are, it might be worth the drive to a distant university. Plus, you can use this paper's extensive bib to find other good stuff to copy while you're there.
A word of warning. These papers are deadly dull. There's more in the second paper for us photographers to use, but the first is good to have just to understand what Sunny means and for those times you have trouble getting to sleep.
Steve
Donald Miller said:Stephen,
Where would one find the paper that you mentioned? Thanks for sharing this information.
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