Another question about filters

Discussion in 'Exposure Discussion' started by Alex1994, Jul 11, 2011.

  1. Alex1994

    Alex1994 Member

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    Hi everyone

    I went on evilBay to buy a Bay 1 yellow filter for my new Rolleicord. I always use K2 yellow as a regular B&W filter. The listing I bought had a pic of a medium yellow (K2 filter) but the description actually said it was a light yellow (K1) filter. Well, I didn't read that bit (note to self: read BEFORE you buy).

    So my question is: will I see more or less the same effect with the light yellow as with the medium yellow I always use? I know the filter has little effect in cloudy conditions, but what about in sunlight, such as dawn/dusk conditions?

    Thanks in advance

    Alex
     
  2. Rick A

    Rick A Subscriber

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    Yes, to some extent, but not quite as pronounced. What is the filter factor for it,one or two with a K1, 1/2 stop or one stop correction?
     
  3. Alex1994

    Alex1994 Member

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    The Rollei manual says the light yellow has a filter factor of 1.5, while the medium yellow has a filter factor of 2.
     
  4. Jeff Kubach

    Jeff Kubach Member

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    Close, but no ciger!

    Jeff
     
  5. Alex1994

    Alex1994 Member

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    What do you mean? Similar effect but not quite?
     
  6. Bruce Osgood

    Bruce Osgood Membership Council Council

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    Keep in mind, you do not want to confuse Factors with Stops.

    My understanding is the Square Root of a Factor is the Stop. In the case of a Factor of two you would open the lens 1.4 Stops and a Factor of 1.5 would be 1.2 Stops.
     
  7. Jeff Kubach

    Jeff Kubach Member

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    Really I don't somke cigers! There is a small difference.

    Jeff
     
  8. Ian C

    Ian C Member

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    Factor = 2^Δf

    Δf = ln(factor)/ln2


    Example:

    #8 yellow = K2 is a 1-stop filter with factor 2

    Factor = 2^1 = 2

    Δf = ln(2)/ln2 = 1 stop


    For the light yellow K1 (#6)

    Δf = ln(1.5)/ln2 = .58 stop (usually rounded up to 2/3 stop)
     
  9. Rick A

    Rick A Subscriber

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    Roughly between 1/2 and 2/3 stop. So, if your lens has two marks between stops, you use the second one. If there is only one mark between stops, use that.