Why such a small aperture?

Discussion in 'Beyond the Basics' started by benjyman345, Mar 21, 2007.

  1. benjyman345

    benjyman345 TPF Noob!

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    hi,

    I was looking through a landscape photography book and came accross a photo of a leaf on the ground. The details said the photo was taken as F/45 at 1 second (ISO 100).

    Why such a small aperture? There is no need for depth of field or long exposure for this photograph.

    thanks
     
  2. Steph

    Steph No longer a newbie, moving up!

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    Maybe it had something to do with the camera used. Some large format cameras use barrel lenses (without shutters).The lens cap is used as the shutter: take it off, time your exposure and put it back on... Not very practical for exposure shorter than 1 second.
     
  3. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Since we have no idea what camera/lens was used, it's hard to say. It might have been MF or LF and focused very close with a bellows, in which case your depth of field becomes very shallow.
     
  4. Torus34

    Torus34 No longer a newbie, moving up!

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    For a static subject exposure taken from a tripod, there's no need at all to fine-tune anything. Long exposures at small f-stops pose no problem as long as reciprocity effects do not come into play.
     
  5. ksmattfish

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

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    f/45 @ 1 sec @ ISO 100 suggests that it was fairly dark; that's EV 9. I'm guessing they were close focusing with a large format camera, and it was dark enough to make precise focusing by viewing the ground glass difficult, so they went with a smaller aperture. Large format lenses usually max out between f/5.6 and f/11. Choosing f/45 may have only be stopping the lens down 3 or 4 stops.
     
  6. RVsForFun

    RVsForFun TPF Noob!

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    ...but not MF or 35mm. There's actually a diffraction effect at very small apertures that makes the picture LESS sharp. I've seen it in 35mm lenses as wide open as f/11. While depth of field increases, it can actually make the photo less sharp overall. For most of my lenses, f/8 is the optimum setting.
     
  7. Sw1tchFX

    Sw1tchFX TPF Noob!

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    ^^^ that's not the case with large format. I've taken test shots of the same thing at f/5.6, f/22, and f/64, and haven't seen the slightest difference in sharpness on 4x5 Tmax 100 negatives.
     
  8. ksmattfish

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

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    There is an aperture diffraction calculator here, along with lots of good info.

    http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

    I've never run into any real world problems in my photography with aperture diffraction with 35mm or larger formats (using typical lenses), although I can sometimes see it with photos from my APS-C DSLRs when I used the smallest apertures ( f/11 is the smallest aperture I'll normally use with my 20D's ). "Real world" meaning looking at fairly large prints as they are supposed to be looked at, not peering at them with a magnifying glass.

    All lenses have a "sweet spot", but that's not only to do with aperture diffraction.
     
  9. Alex_B

    Alex_B No longer a newbie, moving up!

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    I did though ... I sometimes can see it at f/20 with 35mm film or a 35mm sensor, that the image overall becomes slightly softer. Not an extreme effect, but visible.

    Still at f/20 the images then are less soft than with the cheaper lenses I used 10 years ago at f/8 ;)

    So you are right, it is not a real world "problem" but it is a real world "effect".
     
  10. harrisoncj

    harrisoncj TPF Noob!

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    Look at any Ansel Adams photography and you'll know why. Look up the group f/64.
     
  11. Dave_D

    Dave_D TPF Noob!

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    Most of the above explanations are pretty good, but a simple explanation is that the longer shutter allows for better saturation of color, tonal range and detail. The photographer probably needed the small aperture for the desired shutter. My guess is that he was using LF also.
     

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