Shutter speed and aperture question?

I saw this picture of a wasp. The shutter speed was about 1/100 and the aperture at f/9.0. The background is out of focus so there's a very shallow depth of field. But I'm confused on something. I thought a high aperture would make the background in focus. Why did the photographer use a high f-stop for a close-up on a wasp? and since the aperture is almost closed there's not enough light, so if he used a fast shutter speed, shouldn't the picture come out dark. yup I'm confused. any answers would be appreciated. thanks. (future photogrpaher... hopefully)

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  • 1 decade ago
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    Well, first of all F/9 is not really a small aperture (high f-stop, as you called it) and would not have a very long depth of field. I've never even heard of that f-stop, it doesn't sound conventional. I guess it's close enough to f/8 though. f/11 or f/16 would give a longer depth of field and would have made the background sharp.

    They probably used that f-stop so they could keep a reasonably fast shutter speed and would be able to take the picture without a tripod. Although, as Ellenas said, they could have also used a close-up filter.

    The other thing you need to consider is the ISO. The ISO rating is a standard unit of light sensitivity. I don't know whether that picture was taken with a film camera or a digital camera. But with either one, the exposure will depend on the ISO, the shutter speed, and the aperture. It's a "triangle" and you need all 3 parts. Right now, you only know the aperture and the shutter speed. You would also need to know the ISO. So you're missing that information. Depending on the ISO and the lighting conditions, the aperture at f/8 and the shutter speed at 1/100 might have been the correct exposure.

  • 1 decade ago

    Well you've got two of the three things you need to determine a proper exposure for a given EV level. Shutter speed, aperture, and ISO are all needed. Knowing the amount of light (EV level) would also help.

    The closer to the lens you focus, the smaller the Depth Of Field (DOF). So even at f/9 if the subject was relatively close to the lens then the DOF would be pretty shallow.

    F/9 isn't all that small of an aperture. It's only 1 and 1/3rd stop slower than f/5.6. There's an old adage, "f/8 and be there". At one time, f/8 was a pretty standard aperture.

    http://www.joemcnally.com/blog/2008/07/08/welcome-...

    Just after the 6th image he starts talking about a HUGE camera. With all things being relative, the size of the negative, focal length, and aperture size (opening) all go into an equation to give you the f/stop. This f/stop was f/45, but since it's such a grand scale it's akin to being mere inches in front of a 35mm cameras lens. "At f/45, you have about an inch of depth of field." It's an interesting read.

  • 1 decade ago

    The two bits of information that are missing from your description are the focal length of the lens and the distance between the lens>subject>background. Okay, maybe that's three bits of information.

    Here's a bee where the bee is sharp and the background is out of focus. The aperture is f/16 (!!!) and the shutter speed is 1/250.

    http://www.flickr.com/photos/samfeinstein/48779070...

    Why is the background out of focus?

    As Ellenas suggests, this is a very close shot of the bee using a macro lens. Even though I'm at f/16, the background is very far away and it is rendered "fuzzy" because at a close focusing distance, the depth of field for almost any aperture will be relatively shallow. (I see that fhotoace suggested this while I was composing my answer, also.)

    Something that you see all the time is where the photographer has used a relatively small aperture on a relative long telephoto lens. The subject is relatively close to the lens and background is rather far away. This will render the main subject in focus and the background out of focus.

    Close subject, distant background, 200mm, f/5.6:

    http://www.flickr.com/photos/samfeinstein/40844661...

    Close subject, distant background, 55mm, f/7.1:

    http://www.flickr.com/photos/samfeinstein/27436069...

  • Anonymous
    1 decade ago

    if it was a macro photo, an f9 aperture isn't HIGH (as you call it), which is actually SMALL..., but sort of medium, so yes the background would be slightly out of focus.

    an aperture like f16 which is a SMALL aperture would probably have given more depth of field.

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  • Anonymous
    1 decade ago

    maybe they used exstension tubes or close up filters, if the focus is close to the lens then the depth will be short anyway, if the focus is far from the camera the depth will be deeper

    Source(s): this is f16 but exstention tubes were used and the depth has gone: http://www.flickr.com/photos/hellas2008/3073608850...
  • 5 years ago

    confusing matter. seek on bing and yahoo. this will help!

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