Filters, B&W and some newby questions

Discussion in 'Exposure Discussion' started by hoffy, Feb 5, 2009.

  1. hoffy

    hoffy Member

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    Howdy,

    In the past when I have tried B&W film it has always been filter less.

    Then I learnt the Digital side of the world, where the filter was added later...

    Now that I am playing with B&W film again (35mm at this stage) I would like to learn how to deal with filters properly.

    I am planning to start with some Cokins that I already have and Circ Pol filters. For the Cokins, these are basically just warming and grad sunset filters, but at least I can do some experimenting without having to go out and buy a box full of filters. Once I get an indication on how these work, then I will look into expanding my range.

    In relation to exposure metering, what compensation should I apply (if any?) Or should I just bracket and see how I go?

    Cheers

    PS, I will be shooting using in camera metering and I am using 35mm hp + 5
     
  2. Kevin Caulfield

    Kevin Caulfield Subscriber

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    Usually a filter will have the filter factor written on it. As a guide, red filters are usually around 2 stops (8X), so you would normally just apply that amount of exposure compensation as a starting point.
     
  3. ford prefect

    ford prefect Member

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    i'm sure someone will correct me if i'm wrong but when using the ttl (through the lens) metering you shouldnt have to compensate. the meter will "self adjust" to any filter on the lens. so if the filter cuts the amount of light hitting the sensor it will read it as less light and so forth.
     
  4. keithwms

    keithwms Member

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    You are metering through the lens, right? So just put the filter on and see what your meter tells you. (agreeing with the above comment^^^)
     
  5. OP
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    hoffy

    hoffy Member

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    Correct, I will be using TTL metering.

    Cheers
     
  6. Kevin Caulfield

    Kevin Caulfield Subscriber

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    Sorry, correction to my post, 2 stops is 4X.
     
  7. Q.G.

    Q.G. Inactive

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    When using grads, meter without the filter on the lens. Attach the filter, and use the reading unaltered.

    Which (meter without filter) is best when using polarizers too. But then you need to correct the reading by working the (fixed) filter factor (printed on the filter's rim) into the exposure.

    With other filters, metering through them will be fine.
     
  8. Shangheye

    Shangheye Member

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    In summary (because the answers are above), if you are using TTL then if it's a non grad coloured filter, then just put it on and the meter will compensate. If you are using a garduated filter, measure with the camera meter without the filter on, set that reading in the cameras manual mode (so it won't change when you put the filter back on). Put the grad filter back on and shoot. I know a few people who after a while have a "feel" for what correction they need to fool the camera meter when using grad filters and set an under expsoure compensation of anything between 0.5 and a whole stop without switching to manual. Personally, I don't use them often enough to be confident of such a "feel"...especially since with film, I don't get to know if I got it right till later! Kal
     
  9. panastasia

    panastasia Member

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    Make sure you have a yellow #8 filter to start with. You'll see more clouds in your B&W photos, it blocks invisible ultraviolet, and also makes skin tones look better.
     
  10. Steve Smith

    Steve Smith Member

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    But I think you were correct about a red filter being x8.

    I usually reckon on yellow being one stop, orange two stops and red three stops.


    Steve.
     
  11. Stephen Benskin

    Stephen Benskin Member

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    A 25 red is 5X or 2 1/4 to 2 1/3 stops. A 29 is 8X or 3 stops. One of the problems with through the lens metering with filters is the spectral sensitivity of the photo cell. Try it. Lock the camera down and meter a scene. Put the 29 red on and meter it again. If the camera reads only a two stop difference then the photo cell has a high red sensitivity and you will have to compensate for it or you will be underexposing one stop. In truth, it's best to check all filters to see if there is a metering discrepancy.

    Also, when choosing a filter, remember resolution is only as good as the weakest element. You can have the best lens in the world and a crappy filter. The resolution will never be better than what the filter will provide. Personally, I only us B+W filters.
     
  12. Steve Smith

    Steve Smith Member

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    I don't want to appear patronising to the original poster but in case you were wondering B + W Filters is a manufacturer. It doesn't mean Black and White filters!!

    Could be confusing to a beginner who was not aware of the brand.




    Steve.
     
  13. OP
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    hoffy

    hoffy Member

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    no offence!

    I didn't immediately recognise B+W, but have come across them before.
     
    Last edited by a moderator: Feb 6, 2009
  14. John Koehrer

    John Koehrer Subscriber

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    B+W is a manufacturer, B&W is what a lot of us do here:D
    I agree with Steve B regarding the additional compensation for some filters, the mfrs rating is a starting point like so many other things involved in photography.
     
  15. Stephen Benskin

    Stephen Benskin Member

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    Actually, it's the other way around. If the meter disagrees with the filter factor, the meter is wrong.
     
  16. Claire Senft

    Claire Senft Member

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    For myself, I would not recommend Cokin as a filter for best sharpness due to the thickness of the material. But you do as you wish.
     
  17. Tim Gray

    Tim Gray Member

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    Just to add another bit about the TTL metering, my cameras (canon and leica) never seem to have a problem with metering through filters EXCEPT for R72 infrared filters. With HIE, I can simply set the ISO to 400 and a red 25 or 29 filter and be happy. With an R72, I need to set the ISO to 3200 for the meter to compensate.
     
  18. Anon Ymous

    Anon Ymous Member

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    R72 and other infra filters let only IR pass, so your camera's meter isn't very useful. After all, meter cells where meant to be sensitive in visible light. That's why you need to make tests and bracket a lot when using IR films/filters.
     
  19. John Koehrer

    John Koehrer Subscriber

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    The meter just doesn't have the same spectral response as film that's not to say the meter is wrong.
    If you're using 5X as a factor with a 25 then you're not using the mfrs factor of 4X and have confirmed what I said. IE: the mfrs rating is a starting point and you need to determine your very own interpretation of it.
     
  20. Q.G.

    Q.G. Inactive

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    If the meter's purpose is to determine what settings to use to capture the scene it meters on something having the same spectral reponse as the meter, then the meter is not wrong.
    Else (if it's purpose is to determine what settings to use to capture the metered scene on something having the spectral reponse of film - something like, say, film) the meter is indeed wrong.

    Yes, "if".
    If you are using 5x, and if that is not what the manufacturer says to use.
     
  21. CBG

    CBG Member

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    One authoritative source is Kodak, referring to their own BW films shot through their own Wratten number 25 red filter - so there is no issue of confusion as to which film and which filter.

    www.kodak.com/eknec/documents/59/0900688a80300559/EpubBW400CN4036.pdf
    on BW400CN film - Daylight 8x -tungsten 3x

    www.kodak.com/global/en/professional/support/techPubs/f4018/f4018.pdf
    For Plus X - 6x for daylight, and 4x for tungsten

    www.kodak.com/global/en/professional/support/techPubs/f4017/f4017.pdf
    for Tri-X - 8x day and 5x tung

    www.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf
    TMax Films - both 100 and 400 speed varieties - 8x day and 4x tung
     
  22. John Koehrer

    John Koehrer Subscriber

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    One reason(among several) manufacturers went to SBC cells was for improved spectral response. Also Selenium cells were much closer in response than CDS.
    Since no manufacturer has the perfect cell, they compromise. That doesn't make it wrong by ISO standard. Maybe not perfect, but perfect enough.