Bulb exposures - How to determine aperture?

Discussion in 'Beyond the Basics' started by Dimitry, Jul 22, 2004.

  1. Dimitry

    Dimitry TPF Noob!

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    Hey guys,
    the title says it all.
    I just got a Canon Rebel Ti and have been experimenting with it for a bit, got some filters, etc.

    I always wanted to try those long exposures where you see trails of light left by passing cars.

    I got a not-so-good mini-tripod and a remote switch. Still looking for a nice bigger tripod that I can acutally put to use, but all that aside, Im still at loss as to how to determine the correct aperture.

    Will I need a light meter? (sadly this camera isnt equipped with one)
    The only way I can set camera to 'bulb' is to go fully manually where it wont autosearch for a proper aperture for me so Im stuck.

    Do you have any tip, tricks or info for me?
    Thanks guys!
    Dimitry
     
  2. Bob_McBob

    Bob_McBob TPF Noob!

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    It's very hard to find a 'proper' exposure for this type of shot, because changing your settings around can make a very different effect that's not necessarily undesirable. Most people doing this type of photography tend to bracket their shots until they can get a feel for how the exposure is going to look on film.

    Basically, you want an aperture that will expose the lights of the cars, but not overexpose them. I usually work around f/5.6 or f/8 for ISO 100 film, but this is entirely up to you. Then you have to decide on a shutter speed. How long should the trails be? How brights should the streetlights be? I find I often work around 4-8s, but I've done much longer exposures.

    Of course, you can play around with both settings to create many different effects, exact exposure isn't particularly important here. I suggest you grab a roll of cheap ISO 100 film and set up a tripod on a street corner one night. This is one situation where recording all exposure settings is very important, because it's the only way you'll get a feel for how your shots will turn out in the future. Slide film is best for this, but you could try negative film and ask the printer to leave everything unadjusted. I would also consider taking a friend with you, depending on how comfortable you feel being out alone late at night.
     
  3. Dimitry

    Dimitry TPF Noob!

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    Thanks for the insight!
    My camera has this exposure bracketing feature and I wasnt sure what it does. I guess its about that time I read up on it :)

    Dimitry
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Is the meter broken? because every EOS camera has a built in meter.
     
  5. Bob_McBob

    Bob_McBob TPF Noob!

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    For this sort of thing, I use the term 'bracketing' very loosely. Play around with different combinations of settings until you find something that works for you (remember to write them all down!).

    Your camera does have a light meter, but you won't get very far using it for this type of shot. It will likely recommend an exposure that's far too short, or far too long, depending on how much the streetlights and dark background influence it. This is where you have to use your head ;).
     

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