 BetterPhoto Member |
the latitude film what is the latest info about the latitude film?
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John Rhodes |
Beto, we haven't answered this question because we cannot figure out what you are asking. Perhaps you could rephrase the question. John
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Mark Feldstein |
Hey John, I think this is you know who again. Look at the membership date and the way the question is phrased. M
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Alan N. Marcus |
Hi Beto, Actually your questions should read: What is the range of exposure levels what will produce acceptable results when using film? Stated another way, what is the exposure latitude of film? Film latitude is usually expressed in terms of how many f/stops over exposed and how many f/stops under exposed, will still produce an acceptable image. We might say 3 f/stops over and 2 f/stops under; hoverer this is true for negative films when the subject matter is of normal contrast. As subject contrast increases latitude decreases. Reversals films (slide film) display practically no latitude Generally the dynamic range of exposure film will record is 8 f/stops however this can be increased to 10 f/stops under certain conditions. This is not an easy subject to discuss, too many if ands and butts. Alan Marcus
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Raymond H. Kemp |
Derek alert??
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Mark Feldstein |
Yep Ray. I think so. Ok Alan, here's one for ya. Why is the ocean so salty? Mark
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Alan N. Marcus |
Well Mark, Water is the universal solvent. The sun shining on the waters of the earth initiates copious amounts of water to evaporate. As water evaporates it changes state, liquid to gas. This process causes the water to shed any and all minerals it has dissolved. In other words, the mineral content of the evaporated water is left behind. The shedded minerals enrich the waters of the earth making them more concentrated. Later the water vapor falls from the sky in a process we call precipitation. This water is devoid of minerals. Much of this water falls on the earth which is rich in minerals. As the water percolates through the land its solvent action dissolves more of the earth’s minerals. Most of this water will eventually flow to the sea carrying its new load of minerals. A high percentage of this load will be chiefly sodium chloride (table salt), however other salts are also in the cargo. Over eons of time, the waters of the earth gain salt content. This is a never-ending cycle. Alan Marcus
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
With that process, lakes should have high salinity. Or you would think they would. So is fresh water a term that just signifies a low salinity? And since most of the rain that falls to the earth falls back into the ocean, that seems like it would again mean that lakes would have at least a similar salinity. Since runoff from ground water seems like it would have a greater area than the lake.
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John Rhodes |
Alan, actually the myth that water is a "universal solvent" is--well, just that, a myth.
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Mark Feldstein |
Thanks for that excellent explanation Alan. My dad always told me that the ocean is so salty because it's filled with smelt herring. Thanks again ;>)
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Raymond H. Kemp |
Gregory, it's a little more complex. Read this: http://www.palomar.edu/oceanography/salty_ocean.htm Ray
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Ahh, very good! So fresh water is a term for water low salinity. But one point about that link is the article said the red sea is the saltiest body of water. Other sources say the dead sea.
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