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Digital cameras and aperture

Discussion in 'Photography Forums' started by Bagfran, Jan 18, 2004.

  1. Bagfran

    Bagfran
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    Hi,

    I wonder if anyone might be able to answer a question for me, or direct me to where I could find the answer.

    I am fairly new to digital photography, and I have been puzzled as to why it seems impossible to find a digital SLR-type camera with a range of apertures any greater than F2.8 to F11 (at the most)? Is it possible to obtain the same depth of field with these cameras as it is with a true SLR camera (e.g. at a traditional setting of F16 or more) - i.e. do the aperture settings on a digital camera not correspond directly to those on an SLR, is F11 on a digital different to F11 on an SLR?

    I'd be really grateful to anyone who might be able to shed some light on this for me!

    Thanks!

    :confused:
     
  2. ancientgeek

    ancientgeek
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    I presume you weren't looking at the ones that use standard interchangeable lenses, and obviously have the same range of apertures as the 35mm SLR, because they use the same lenses.

    You should understand that although digicams are often described as having, say, a 35 to 105mm zoom lens, it's not actually true, they are just saying the angle of view corresponds to that lens range on a 35mm camera. Because the light sensor is normally much smaller than a 35mm frame, the actual focal length is smaller. My coolpix 950 is really 7-21mm focal length, but it's equivalent to 35-105.

    Next, you should understand that although the depth of field depends on the subject distance and the aperture, it's the subject distance measured in focal lengths, not measured absolutely. My coolpix at two feet subject distance behaves like a 35mm camera at ten feet so far as depth of field is concerned.

    f11 says your lens opening is one eleventh of the focal length. So a 55mm lens at f11 has a 5mm opening. The brightness of the image is going to be the same whatever the focal length of the lens, but the depth of field for the same picture is going to be completely different. In the case of my Coolpix 950, for the same angle of view, aperture and focussing distance, I'm going to get five times the depth of field of a 35mm camera.

    It's much harder to throw the background out of focus than with a larger camera.
     
  3. woody67

    woody67
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    The pin sharp subject and an out of focus background is something that I miss from digicams.

    The only reason I have kept my SLR and telephoto lenses is so that I can get those portrait shots that make the subject really stand out.

    I suppose the same effect can be acheived with a little photoshop, but It never seems to be the same.

    And even with a the LCD, you still can't see just how blurred the background is - not like a good old preview lever
     
  4. wilber

    wilber
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    The prosumer models can do this - I've got good results from a Canon G3 but with my Oly E10 & Canon 300D the results are as good as those from a film camera
     

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