Why Bulb

Discussion in 'Beyond the Basics' started by mysteryscribe, Jan 4, 2007.

  1. mysteryscribe

    mysteryscribe TPF Noob!

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    From time to time the term Bulb as a shutter speed shows up. I wonder how many people know why that term was adopted for timed exposure. Why was it called bulb not sammy for instance.

    By the way I know, so it's just an interesting bit of trivia.
     
  2. castrol

    castrol TPF Noob!

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    I always thought the use of a rubber bulb to squeeze air through a tube and
    actuate the shutter release was where the term originated...
     
  3. mysteryscribe

    mysteryscribe TPF Noob!

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    quite right.... I went to two different photo courses one was college level and not one ever said. For years i thought it was the flash bulb that created the term. I started before electornic flash.

    Bulb is a newer invention than the time exposure which doesnt require a bulb. First there was no shutter at all. then the Istant and the Time later came bulb for shorter exposures than time.

    that is my understanding of the evolution of the the shutter.
     
  4. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Some more trivia:

    Where does the "f" in f/stop come from?

    Where does the the term "stop" come from?
     
  5. Philip Weir

    Philip Weir TPF Noob!

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    I'm going off my memory, so I'm sure someone will correct me if I'm wrong, but as you know setting the shutter on a particular shutter speed opens the shutter for that amount of time. Setting on "T" you press the cable release twice to open and then close the shutter. when setting on "B" you press the cable release to open and release it to close. Old fashioned flash bulbs were fired by opening the shutter, which sent an electrical signal to the bulb, which then flashed. The electrical signal is almost instantanious but the material in the flash bulb took longer to ignite and burn to its full power, thus needing the shutter to be open longer than with electronic flash. Normally you would squeeze the cable release or air release [can't remember the proper name] then when the flash has gone of, you would then release the shutter to get the full effect of the flash. Hence "B" is for bulb. Trust that helps.
     
  6. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    :) The term is much older than flash bulbs. Castrol is right.
     
  7. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    f stands for focal length, as in the ratio of focal length to effective aperture diameter.

    Stop comes from aperture stop, which was the device used to control aperture size before the iris diaphragm. An aperture stop could be as simple as a plate of metal with a hole in it that would be inserted into the lens. More advanced cameras had a ring of various sized holes that could be turned so the photographer could select the one they wanted. These were usually set up so that turning the wheel in one direction would double the exposure each hole, and turning it in the other direction would half the exposure each hole. Eventually the term stop came to mean doubling or halving the exposure.

    "Stop" in the term "aperture stop" originally comes from music. If you look up the definition of the word "stop" in regards to music it means:

    a. The act of stopping a string or hole on an instrument.
    b. A fret on a stringed instrument.
    c. A hole on a wind instrument.
    d. A device such as a key for closing the hole on a wind instrument.
    e. A tuned set of pipes, as in an organ.
    f. A knob, key, or pull that regulates such a set of pipes.

    Whoever invented the aperture stop must have been a musician or known about instruments.
     

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