long exposure help

Discussion in 'Beyond the Basics' started by ajmall, Dec 20, 2005.

  1. ajmall

    ajmall TPF Noob!

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    in the past when i've taken long exposure shots of traffic on roads, buildings etc. they frequently came out greyish rather than black. the general exposure was ok, subjects weren't too bright or dark just black wasn't quite black.

    i seem to recall reading briefly somewhere about shutter speeds greatly affecting the amount of black you get in a long exposure. are there general rules of night shots/long exposures with regards to shutter speed vs aperture.

    my usual method was to take a variety of apertures and shutter speeds but i'd like to nail it down a bit more.

    thanks
     
  2. Dave_D

    Dave_D TPF Noob!

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    I would take a look at the specs on the website of the film type you are using and see if it mentions anything about exposure times vs. reciprocity.
     
  3. Hertz van Rental

    Hertz van Rental TPF Noob!

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    If you go to the manufacturers website you should find the reciprocity compensation chart. It should be on the tech sheet that comes with the film if you use pro film.
    However, as most b&w films behave pretty much the same the following data will give acceptable results. Use the data to plot a graph if you want to work out compensation for different exposures more accurately.

    Indicated exp. time / Aperture adj. / Development adj.
    1/100,000 +1 stop +20%
    1/10,000 +1/2 stop +15%
    1/1,000 None +10%
    1/100 None None
    1/10 None None
    1 +1 stop -10%
    10 +2 stops -20%
    100 +3 stops - 30%

    Colour is a lot more complex as you have to use Colour Compensation filters too, and these vary with film and exposure.
    As a general rule exposures between 1/2,000 and 1/2 secs require no adjustment.

    (sorry but it's taken out all the spaces in the chart. Hope it makes sense)
     
  4. ajmall

    ajmall TPF Noob!

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    oops, guess i should have mentioned i'm shooting digital now...
     
  5. Hertz van Rental

    Hertz van Rental TPF Noob!

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    Digital? Then you can tweak it in PS.
     
  6. Rob

    Rob TPF Noob!

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    I tend to up the contrast 10% and drop the brightness 10% on most images for the web anyway, but this would probably work for you as well!

    Rob
     

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