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Thread: Filter Factors

  1. #1

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    Ok here is my problem, years back I had done testing with a color chart and each filter by exposing the film with the filter. From the negative of the color chart I picked the best "factor" that gave me a Zone V. So in the move I lost the color chart and I lost the list with the factors I had made.
    Not having a way to test now I was following the reccommended factors with less than satisfactory results. So unpacking my old issues of View Camera I came accross about an article by Simmons about the filter factors and how Hutchins uses the "meter through the lens and add..." So I am wondering has anybody used this method?
    I understand that meter cells are not color corrected, but I would like to know how close this method can take you to a correct exposure.

  2. #2

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    I am unsure if you are working in color or black and white...but here is my experience. I have a Zone VI modified Pentax digital meter and I work exclusively in black and white. I always meter the scene through the filter with this meter and it is much more consistant, in my experience, then using filter factors. I don't know how an unmodified meter would react in similar circumstances. Good luck.

    Regards,
    Donald Miller
    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

  3. #3
    lee
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    my experience is that the unmodified and tbe modified give the same reading within acceptible margin of error. Like a third of a stop. I have tested this with several meters including my own.

    lee\c

  4. #4

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    But how about adding the "extra" factor Hutchings reccommends? for example from the article the chart indicates:

    For a medium orange filter #16 meter through the filter and add 1 stop. Does that work?

  5. #5

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    Maybe this is wrong, but Hutchings may have been talking about the effect filters have on objects that are shaded (and so have a bluer cast to them). Personally, I never used his adjustment factors since there is enough to remember already, and the changes to me would be so minor as to not be noticeable at least by me. It's easier to just meter through the filter, or use the generally accepted filter factors.

  6. #6
    Les McLean's Avatar
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    A few years ago I spent a couple of hours and a couple of rolls of 120 film testing my filters to determine my own factor. The procedure I used is as follows. I chose a landscape subject with a full range of tones and using my spotmeter metered and exposed for the shadows in my normal way with no filter in place. This negative is my reference. I metered the scene through the filter being tested and made a second exposure and then underexposed by one stop and over exposed by one stop. Obviously the last three exposures were made with the filter in place. I followed this procedure using 5 filters, red, orange, yellow,green and polariser. When the film was processed I selected the negative showing the shadow detail that matched the reference negative.
    This method may not be the most scientific and does not take into account the effect that the filter has on the cells etc., but it works for me. If I replace a filter I carry out the same test on the new one.
    "Digital circuits are made from analogue parts"
    Fourtune Cookie-Brooklyn May 2006

    Website: www.lesmcleanphotography.com

  7. #7

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Les McLean @ Jan 6 2003, 01:27 PM)</td></tr><tr><td id='QUOTE'>A few years ago I spent a couple of hours and a couple of rolls of 120 film testing my filters to determine my own factor. The procedure I used is as follows. I chose a landscape subject with a full range of tones and using my spotmeter metered and exposed for the shadows in my normal way with no filter in place. This negative is my reference. I metered the scene through the filter being tested and made a second exposure and then underexposed by one stop and over exposed by one stop. Obviously the last three exposures were made with the filter in place. I followed this procedure using 5 filters, red, orange, yellow,green and polariser. When the film was processed I selected the negative showing the shadow detail that matched the reference negative.
    This method may not be the most scientific and does not take into account the effect that the filter has on the cells etc., but it works for me. If I replace a filter I carry out the same test on the new one.</td></tr></table><span id='postcolor'>
    That is a good test, at least you know you will get shadow detail.

  8. #8
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    Les, doesn&#39;t the polarizer transmit different amounts of light depending on the amount of rotation of the filter + direction of the light?
    hi!

  9. #9
    Les McLean's Avatar
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    Brian,

    Yes it does, well spotted I&#39;ll give myself a slap on the wrist for not making the point. I only use the polarising filter in B&W when I&#39;m looking for a really dramatic sky so I combine red and polariser. Therefore when I test I set it to fully polarise the light and make sure that the sun is at rightangles to the camera to maximise the effect.
    "Digital circuits are made from analogue parts"
    Fourtune Cookie-Brooklyn May 2006

    Website: www.lesmcleanphotography.com

  10. #10
    Ed Sukach's Avatar
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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (lee @ Jan 6 2003, 07:29 AM)</td></tr><tr><td id='QUOTE'>my experience is that the unmodified and tbe modified give the same reading within acceptible margin of error. &nbsp;Like a third of a stop. &nbsp;I have tested this with several meters including my own.

    lee&#092;c</td></tr></table><span id='postcolor'>
    The manufacturing tolerances applying to Photographic Light Meters are most probably the limiting factors here. Gossen only claims an accuracy of +/- 1/3 "stop" for their UltraPro.

    The manufacturers do not provide easy access to that information. Many years ago, I calibrated a Honeywell "1 degree/ 21 Spot" meter (an attempt to use it in an industrial application) and after a monumental struggle, found that the manufacturing tolerance was only +/- 1/2 "stop".

    Given all the variables in the process; film speed tolerance; shutter speed and aperature tolerances; and sundry others, I would not really be too concerned over *exact* exposure.
    Carpe erratum!!

    Ed Sukach, FFP.

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