2 filter questions

Discussion in 'Miscellaneous Equipment' started by thefizz, Nov 8, 2005.

  1. thefizz

    thefizz Subscriber

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    1) I understand that Circular Polarizers are used for cameras with built in metering and Linear for cameras without any metering. Is this the only difference, do they preform the same?

    2) Which colour filter is best for improving contrast in clouds when no blue sky is visible.

    Regards,
    Peter
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    1) Sort of. Some (mostly older) cameras with built-in metering and manual focus can handle a linear polarizer, but other than that, yes circular and linear polarizers do the same thing.

    2) When no blue sky is visible, there isn't much to do to improve contrast in clouds. You could try an ND grad to prevent the clouds from being overexposed, so you'll get more detail, but the normal yellow-orange-red filters for B&W filter out varying degrees of blue, so they need blue sky to work.
     
  3. glbeas

    glbeas Member

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    Circular polarizers are for use with autofocus cameras, linears seem to make them act screwy. As far as cloud filtering use the same filter that darkens the blue sky, as the clouds have a blue cast in the shadowy parts from skylight filling the shadows. If the cloud cover is so dense the there is no blue sky to fill the shadows the best thing I've seen that will really bring out detail is infrared film.
     
  4. Lee L

    Lee L Member

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    I don't know about autofocus cameras... never used one or studied its behavior. But circular polarizers are required on cameras that polarize light in the process of sending the light to a meter sensor, which often happens for TTL spot metering (and perhaps for some matrix metering systems... again not my forte). The camera instruction manual will let you know. I use circular polarizers because they are required by my main SLR, which uses spot metering in a way that polarizes light. Many TTL metering systems do not require circular polarizers.

    BTW, I've had a B+W circular polarizer in which the film separated from the glass around the edges. B+W replaced it about 10 years after purchase, no questions asked. That filter was bought in the US and returned under warranty in the US. It cost a lot, but the warranty made it well worth the price. The US distributor however, refused to honor any kind of warranty on a B+W cyan filter purchased in Germany (which ended up extremely heavily etched all over while stored in the original packaging).

    Lee
     
  5. thefizz

    thefizz Subscriber

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    Thank you all for the clarification. I just wanted to make sure before I get a Linear Polarizer for my RZ67.

    Peter
     
  6. thefizz

    thefizz Subscriber

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    Here is another question:

    I have been comparing prices for various filters and have found that some Hoya Multy Coated filters are actually cheaper than the standard single coated Heliopan.

    Are single coated Helipoan so good that they are better than Hoya HMC filters?

    Peter
     
  7. vet173

    vet173 Member

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    Yup