calculating ISO etc

Discussion in 'Film Discussion and Q & A' started by Lexi1016, Mar 19, 2012.

  1. Lexi1016

    Lexi1016 TPF Noob!

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    I am having trouble remembering how to calculate ISO changes with your shutter speed and f-stops. Thanks!


     
  2. umashankar

    umashankar TPF Noob!

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    I usually push the ISO based on existing light, if its a
    sunny day 100
    bright but bit clowdy (or inside a room) 300 or 400
    Dull light 500 - 600
    very low light, during or soon after sunset - 600 - 800
    Night -1600 or above

    I choose the shutter speed and f numbers accordingly,,
    If you are using a tripod and making shots you can reduse ISO and increase the exposure time with requred f numbers...

    there is no such fixed formula for composition all you have to do is expriment, Just get to know the basics... You will learn your own unique composition


    happy photos :)
     
  3. Lexi1016

    Lexi1016 TPF Noob!

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    Thank you. I havea question on my test asking my to calculate the shutter speed and f-stop from a certain ISO to another. So, if it was at 1/60 @ 5.6 at an ISO of 400 what would be at 800 for a 1/60 and f stop at ? And shutter speed ? If it was at a 5.6
     
  4. 2WheelPhoto

    2WheelPhoto TPF Noob!

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    google an ISO/shutter/f-stop chart
     
  5. umashankar

    umashankar TPF Noob!

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    I suggest you to go thru this
    Sunny 16 rule - Wikipedia, the free encyclopedia
     
  6. Rephargotohp

    Rephargotohp TPF Noob!

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    It's easy

    Doubling/halving ISO = 1 Stop
    Doubling/Halving Shutter speed = 1 Stop
    Dividing/Multiplying f/stop by Square root of two....hahaha...OK just use 1.4 = 1 stop. Just make sure you know your f stiops so you don't write f/7.9

    If You double your ISO fr0m 400 to 800, Your shutter speed goes from 1/60 to 1/125 ( yes there is no 1/120)


    If you double your ISO from 400 to 800, your aperture goes from f/5.6 to f/8

    Now that I answered the uestion, "I" get the A on your test
     
  7. Lexi1016

    Lexi1016 TPF Noob!

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    That's exactly what I needed! Thank you!
     
  8. maris

    maris TPF Noob!

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    I'd be fascinated to know what you are planning. I've never been able to change the ISO of a film in some decades of photography. It's a fixed value characteristic of a film and it is measured by a strict testing protocol. Ok, if you have a particular lighting condition and particular aperture and shutter speed requirements it's good to know what ISO film to buy. But you can't change it.
     
  9. willis_927

    willis_927 No longer a newbie, moving up!

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    Unless you have a digital camera, in which case you can change the ISO as you wish...
     
  10. compur

    compur Been spending a lot of time on here!

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    Most films can be "pushed" or "pulled," that is, shot and processed as if they had higher or lower ISOs than the rated "box speed."
     
  11. maris

    maris TPF Noob!

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    Yes! Pushing and pulling film are sophisticated techniques that can change the way pictures look. Advanced photographers do this for special effects or when lighting conditions impose shutter speed and aperture compromises.

    Unfortunately even the most extreme "pushes" don't actually make film much faster or more sensitive to light. A 100 speed film pushed to 400 (say) by extra development will still have empty shadows. What was never recorded by exposure can't be brought out by development. And that pushed 100 speed film won't look like a true 400 speed film. It may look better, it may look worse. Only the photographer knows. It's part of the art.

    Pulling film is marginally more useful. But not in terms of actually reducing film speed. Negative-acting film is tolerant of extra exposure, maybe a stop or two or more, but eventually its highlights burn out and no development however mild can save them. Strongly pulled film tends to deliver dense low contrast negatives that are harder to work with and deliver "flat" results. Maybe that's just what the clever photographer needs to record a scene with an extreme brightness range. Again, it's part of the art.

    In contrast to modern digital picture-making film does not allow free use of ISO as a third variable in combination with shutter speed and aperture in order to formulate routine exposure strategies.
     
  12. gsgary

    gsgary Been spending a lot of time on here!

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    You can pull and push film, one of the best is HP5 (iso400) but can be shot at ISO3200 with good results
     

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