 anonymous |
Aperture and focus
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Irene Troy |
Jennifer – I think that you may be a little bit confused. Although most of my photography focuses on travel and nature subjects, the principals of exposure apply regardless of subject. To answer your basic question of how to achieve a sharp image with a limited or even blurred background you should know the following: Aperture, or F-stop is the measure of depth to your image; (depth of field is the proper term). The size of your aperture – the f# - determines the angle or degree of sharpness of the lens – the depth of field. The higher the f# (F22 is often the highest number on many lenses) the smaller the aperture and thus greater the depth of field; conversely, a smaller F number, the larger the aperture, thus the shallower the depth of field. Shutter speed regulates how quickly the shutter operates – the faster the shutter speed the quicker the shutter closes. Shutter speed is important when attempting to capture moving subjects – a fast shutter speed stops action, a slow shutter speed blurs action (desirable in many type images). If you are attempting to capture a subject (in your case, an infant) and want the background to be blurred while the subject is in sharp focus, you need to use a large aperture – low F stop #. When attempting to capture a scene in which you wish to blur the background while keeping maximum sharpness on the subject, the use of a tripod is almost essential. Place your camera on the tripod; set your f-stop to a low # (large aperture) focus in tightly on your subject; and make your exposure. If you are shooting digital you can check your exposure and sharpness on the lcd screen and make any adjustments necessary to increase sharpness or adjust depth of field and thus further isolate your subject. If you are attempting to photograph a moving subject, you will need to adjust your shutter speed to stop movement (if this is what you prefer) and then adjust aperture to produce a good exposure. Just keep in mind that a smaller aperture – larger f stop # will produce greater depth of field, thus making the background sharper. Both shutter speed and aperture are important for creating the correct exposure. Both are influenced by the amount of light on your subject and the ISO (film speed) at which you are shooting. Higher ISO often means greater latitude in selecting exposure, but a higher ISO often also means a greater risk of noise/grain in the final image. I hope that this is understandable and helpful. If you are looking for advice on photographing babies, I am sure that one of the many very knowledgeable studio photographers here will be able to help you much more that I can.
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anonymous A. |
I'm afraid I can't see your pictures, Jennifer, but as Irene pointed out, if you are using a large aperture (that's one with a small f number like f2.8) less of your picture sill be sharp...if you are photographing a baby at, say 3 to 5 feet from the camera, the subject will be sharp, the background blurred or soft). To get the exposure right with this large aperture, the shutter speed will be fast, which should freeze subject and prevent hand shake spoiling the picture. The relationship between shutter speed and aperture is constant at normal shutter speeds...each f number (called a "stop") lets in half as much light as the next stop above it; so for every stop you open up, you have to double the shutter speed (halving the time the shutter is open to let in light) to keep the same exposure.
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anonymous |
Thank you, this will help, I was trying to read the manual and it confused me and I asked a friend and she confused me more.
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Ariel Lepor |
DOF calculator: http://www.dofmaster.com/dofjs.html Information on aperture and related settings: What you want to do is set up on a tripod, get back from your subject, and use zoom. This way you get a narrow DOF and still a fast shutter speed. You could also sacrifice smoothness if you want, use a high ISO, quick shutter speed, and a wide aperture (lower the number, the wider). Ariel
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