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  1. #1
    Ken
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    Greetings,
    My Gossen Luna pro F, compared with the meter in my Canon F1N, indicates an exposure one stop less than that of the Canon. Incident, reflected, shadow or highlight, it is dfferent. I have compensated for the difference when making the exposure, I'm just wondering if this is unusual.
    Regards.
    Ken

  2. #2
    Eric Rose's Avatar
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    I just finished posting something about this last week. You might want to check it out. Essentially the Gossen is a Euro meter and they are balanced for 5500 degree Kelvin whereas the Canon being a Japanese meter is balanced for 3200 degrees Kelvin. The difference works out to exactly 1 stop. I see the same thing between my Gossen and my Pentax spotmeter.

    It is my theory that this is percisely why so many people de-rate their asa on most B&W films as they find using the Japanese model the exposures are over by 1 stop. Personally I trust my Gossen and adjust my Pentax to compensate for the error.

    Eric
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    "civility is not a sign of weakness" JFK

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  3. #3

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    Interesting. I'm assuming the meter in my Nikon N80 is balanced for 3200K as well.

    So, the question is, which is the "correct" or "best" meter reading? Wouldn't that depend on what the film is balanced for? I seem to recall that "natural" light is in the 6500k range (it may have been even lower, I don't remember exactly).

  4. #4

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    The measurements of degrees Kelvin are measurements of color temperature and not measurements of light intensity. The color of a northward exposure to blue sky is normally acknowledged as being 5500 K. Thus daylight color film is balanced for this color temperature.

    Tungsten film which is color balanced for a warmer light source (more yellow) will render a daylight exposure as excessively blue. The higher the degrees Kelvin the colder the light source and conversely the warmer temperatures are lower in degrees Kelvin.

    I do not believe the measurement of color temperature that a meter is calibrated for will cause a measurement of differing amounts of light intensity.

    Light meters, even the best of them, are prone to differing measurements and are influenced by such things as internal and external flare and the sensitivity of the photocell to IR and UV emissions. That is why green pine trees very often are a lower negative density (in a black and white film) then what a meter reading would indicate (the amount of IR emission).

    This is further complicated in black and white film by the sensitivity of the film emulsion toward red in the case of panchromatic materials and blue in the case of othochromatic materials. I think that it is important to gain experience with a particular meter and learn it's characteristics. From this knowledge, one is able to meter a scene more accurately and in conformity with the materials used.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

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  5. #5
    Eric Rose's Avatar
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    most slide films are balanced for around 5500 I think. for the most part so is B&W films as they seem to take an extra stop to expose them when under tungsten lights. It's not so much which is right or wrong, it's a matter of testing to see what works with your setup. It's my opinion this is why so many people fiddle with their asa's. When you combine this fudge factor with trying to understand the zone system it's no wonder people get all confused.

    The test data that is out there shows that how a meter is color balanced also determines it's sensitivity to illumination. Think of it as a band pass filter.

    I do agree that if you take 10 meters and compare them side by side you will probably get 10 different readings. However the error should only be within 1/2 stop either way. Moreover, if you did a plot of Euro meters compared to Japanese meters you will see the graph will show a 1 stop spread on average between the two, deviations normalized.
    www.ericrose.com
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    "civility is not a sign of weakness" JFK

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  6. #6

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ken @ Mar 24 2003, 11:02 AM)</td></tr><tr><td id='QUOTE'> Greetings,
    My Gossen Luna pro F, compared with the meter in my Canon F1N, indicates an exposure one stop less than that of the Canon. Incident, reflected, shadow or highlight, it is dfferent. I have compensated for the difference when making the exposure, I&#39;m just wondering if this is unusual.
    Regards.
    Ken </td></tr></table><span class='postcolor'>
    I am not sure about this but both the meter and the camera can (and should) be calibrated.
    I know that this is routine with spotmeters.
    art is about managing compromise

  7. #7

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    OK. I think I&#39;ve got this.

    So, the Japanese Meters (like the one in my N80), will be balanced for 3200K. European meters will be balanced for 5500K. Natural lighting tends to be about 5500K. So, given the same picture, it looks like the European meters will read about 1 stop less exposure than the Japanese meters (it was never stated directly which way the difference was to I&#39;ve inferred it from otehr comments).

    Basically correct?

    Now, why the difference? I did notice when I was working in a photo lab that the oriental customers almost universally preferred their prints lighter by 1-2 stops than I would have preferred. Could that be it?

  8. #8
    Ed Sukach's Avatar
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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Mark in SD @ Mar 24 2003, 02:17 PM)</td></tr><tr><td id='QUOTE'>So, given the same picture, it looks like the European meters will read about 1 stop less exposure than the Japanese meters (it was never stated directly which way the difference was to I&#39;ve inferred it from otehr comments).

    Basically correct?</td></tr></table><span class='postcolor'>
    I&#39;ve Been following this .... I have two meters now, a Gossen Ultra Pro and the internal meter in my Olympus OM 4.

    Both agree with each other - near as I can tell, dead-on.

    Must be me. I seem to be eternally the "odd one". I don&#39;t subtract 10% - 15% of time in the JOBO processor - and now my Japanese and German meters agree with each other.

    I have *no* idea why they should be different. I&#39;ve worked with some sophisticated light-measuring equipment - Cascade Photomultiplier based systems ... and there was *no* bias - as far as color temperature goes. Couldn&#39;t be, where light energy at discrete frquencies was being measured. I *suppose* one could deliberately introduce filters to create a bias, a&#39; la Fred Picker - but for a meter that is intended for *universal* use - why would you?

    Is everyone SURE of that 3200K - 5500K difference? - Or are we looking at a calibration problem?

    --- Uh ... tell me we&#39;re NOT trying to verify sophisticated light meters by the "Sunny 16 Rule" ...
    Carpe erratum!!

    Ed Sukach, FFP.

  9. #9

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    I think that I will go back to doing what Edward W. did...not using a meter at all. I understand that he made most of his images without the impediment of such extraneous and untrustworthy devices. Probably would be a big boost to my photography. Learn to trust my eyes. Work with the materials and learn to know them and what they are capable of. I have heard that if he had relied on a meter to make his "Church at Hornitas" he would have underexposed the image by at least 3 stops...go figure&#33;&#33;&#33;&#33;
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

    Visit my website at http://www.donaldmillerphotography.com

  10. #10

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    Donald,

    Your comment above about light color and light intensity not being related...wasn&#39;t the whole idea behind the Zone VI modified meter that Any Old Pentax Spotmeter&#39;s readings were off because it didn&#39;t do a good enough job measuring the color of light?

    And to those who use both Gossen and Pentax...which do you prefer? I have looked at the Gossens and they seem harder to use, especially for zone system thinking. True?

    dgh

    David G Hall

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