Considerations with film speed...

Discussion in 'Beyond the Basics' started by SquirrelNuts, Sep 16, 2003.

  1. SquirrelNuts

    SquirrelNuts TPF Noob!

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    I am new to 35mm SLR photography. I shoot at least one roll every day and I am learning from my mistakes. Each day, the overall crop is better. I am applying what I learn from botched shots and my book and online readings, and I can tell a dramatic difference in everything.

    My mistake for today: Assuming that I can get great detail from Polaroid 800 speed high definition film. I tried taking some gun and knife pictures and some turned out ok, but nothing spectacular.

    Tomorrow I am going to use some 100 speed Fuji to get better detail. I will be using a tripod. I am comfortable selecting F-stops and shutter speeds for 400 and 800 speed film. Do I need to make any changes in my F-stop and shutter speed selections going to a slower film? Maybe open up a F-stop from what I regularly would? Should I just stick to settings I am already comfortable with?

    I am using a Canon AE-1 Program until my Nikon N80 arrives from Adorama. I generally use the camera in S/Tv mode, but I am actually just adjusting the shutter speed until the camera selects the aperature that I want to control the depth of field. I do this because the shutter speed dial is right next to the shutter release and I can do it without looking. Should I just continue using the F-stops that I like and let the camera pick the shutter speed in an indirect way?

    -SquirrelNuts
     
  2. SquirrelNuts

    SquirrelNuts TPF Noob!

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    I forgot to add...the AE-1 Program has a film speed selector. When I set it to the proper speed, will that take care of adjustments?

    -SquirrelNuts
     
  3. ksmattfish

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

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    ISO 100 film is 2 stops slower than 400, and 3 stops slower than 800.

    It doesn't really matter how you arrive at the settings you use as long as they are the right ones for your purposes. Typically, if DOF is your prime consideration, you would use the Av setting, but use whatever works for you.

    Setting the camera to the proper ISO adjusts the light meter/program settings accordingly.

    If you were to set the camera on full manual exposure, and select the aperture you need for the DOF you want, you would still just be turning the shutter dial until the meter shows you have the right exposure.
     
  4. Scott S

    Scott S TPF Noob!

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    In the same vein... Let me know if I'm wrong please...

    If I go from ISO 400 to ISO 100 that's 2 stops slower, and that will affect my possible aperture settings correct? So ISO 400 at 1/250 and f/11 would mean ISO 100 at 1/250 but f/5.6? So if I wanted a bit of depth of field I'd then have to go to ISO 100 - f/11 but at 1/60?

    Am I learning anything yet?
     
  5. motcon

    motcon TPF Noob!

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    no....

    if you want increased dof, just stop the puppy down. you don't change film speed to get dof, just aperture. change the aperture with the film rating at whatever you choose, then meter for shutter. the entire system is based on ev; exposure values with film speed being constant.

    http://www.chem.helsinki.fi/~toomas/photo/ev.html
    http://www.uscoles.com/exposures.pdf

    yah, you are...you have the sequencing of stops correct (in your example). just distance f stop and shutter speed from ei (film speed). all three are needed to calculate exposure, but as a rule aperture and shutter are married. as mentioned, i am a dof shooter as well. dial in aperture, find the shutter mate, fire away.
     
  6. Scott S

    Scott S TPF Noob!

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    I think I was a bit confusing with 3 comparisons at a time.

    400 is twice as sensitive as 100, so open the aperture 2 stops, right?


    Now talking about the same film speed...

    f/5.6 isn't much DoF, so I want to go to f/11 - 2 stops. I'm decreasing the amount of light to 1/4, so I increase the shutter 2 stops to 1/60 to get 4 times as much light on the film. Yes?


    So ISO 100 f/11 1/250 would give me the "same pic" as ISO 400 f/11 1/60?
     
  7. motcon

    motcon TPF Noob!

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    semantic issue, but may as well get the lingo down: same exposure.

    and almost...the other way around:

    ei 100 f/11 1/60

    same exposure as

    ei 400 f/11 1/250

    easiest way to remember: faster film, faster shutter.
     

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