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Old Dec 15, 2009, 9:17 AM   #1
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Default What are the benefits of apeture priority ?

What are the benefits of apeture priority ?...what would be the best situation to use it in ?
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Old Dec 15, 2009, 9:31 AM   #2
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Use aperture priority when you want to control the depth of field. For instance, if you are shooting macro with a macro lens, you'd probably set the aperture to something like f18 or something like that so you'd have a large depth of field. Or if you are taking a picture of a single rose in a garden (not a macro shot) and want to blur the background, you'd want to use an aperture of f2.0 (small numbers mean small depths of field but bigger lens openings, larger numbers mean bigger depth of field but smaller lens openings). There's more to depth of field than just the aperture, but this gives you an idea of when you would want to use aperture priority.
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Old Dec 15, 2009, 9:37 AM   #3
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Hi there, Anthony_b-

Harriet has given you an excellent description of the advatanges of Aperture Priority. Its primary use is in controlling Depth of Field. I find that I use Shutter Priority more than I use Aperture Priority.

Sarah Joyce
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Old Dec 15, 2009, 9:38 AM   #4
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Three reasons come immediately to mind.
  1. When you want to control the depth of field.
  2. When you want to fix the ISO and don't want the shutter speed to get too slow.
  3. When you want to use a lens where it performs best.
I use aperture priority almost exclusively. I use it for sports and for available light photography. The large aperture limits the depth of field so the subject in sports/action/wildlife photos is isolated from foreground and background elements. And a large aperture lets me shoot indoors without resorting to high ISO settings and the increase in image noise that accompanies them. Lastly, selecting a particular aperture lets me use my lenses where they are sharpest and/or have the least chromatic aberration, given the objective test data available at places like SLRGear.com ahd PhotoZone.de.

Of course, if all someone has is small aperture lenses, they won't see much benefit to Aperture Priority mode.
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Old Dec 15, 2009, 9:59 AM   #5
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Great input, thanks...I guess it would be beneficial for portrait shots as well ?...also, my son is having a Christmas recital tomorrow at school. Should I use this mode ?...I'm pretty sure the lighting will not be the best.

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Old Dec 15, 2009, 10:24 AM   #6
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In school events, aperture priority would allow you to specify the largest aperture, which will let you adjust the ISO so you still get shutter speeds that are fast enough to prevent motion blur. If you don't have a large aperture telephoto lens, then your options are limited. You can get close so you can get a larger aperture, but then you're looking up at the stage which will give you an odd persective. The best option is to have a long lens (so you can shoot from the back of the room and get a better perspective) with a large aperture (so you can get a fast shutter speed without cranking up the ISO too much.)
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Old Dec 15, 2009, 11:33 AM   #7
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Some good advice here. Let me just add the following:
Understand that in Auto, P, Aperture or Shutter priority the camera is still determining exposure. There are always going to be instances where the camera chooses the WRONG answer. The issue lies in HOW the camera determines exposure. Your camera likely has different metering modes - evaluative, center weighted, spot etc... If you look at your camera manual you will see some diagram of how much of the image the camera looks at when determining overall exposure. Beyond that, each brand (and sometimes camera model) has natural tendancies. For example, a given camera may be engineered to protect highlight clipping. So, if there was something bright in the image that camera may underexpose the entire image more so than another camera might.

You'll have more success with proper exposures if you learn the different metering modes your camera offers and learn your specific camera's exposure tendancies. That way, when you are using Aperture Priority you can evaluate the scene and see whether you need to ADJUST the exposure the camera has chosen. In aperture priority, this adjustment is called Exposure Compensation. With EC, you're basically recognizing that for a given scene YOU want the shot brighter or darker than the camera is going to GUESS the exposure at.

In a lot of instances, it really isn't too complex. BUT, in low light situations it's extremely important to get as close to the correct exposure as possible. You'll be using higher ISOs 1600, 3200, 6400 for plays and at those ISOs you don't want to have to adjust exposure in post processing. If you do you'll either have blown highlights or if the image was underexposed and you correct for that, you'll bring out a LOT of noise in the image.

As a general rule - when taking photos of people in low light you want FACES properly exposed. Until you get more familiar with your camera and the metering modes, use the LCD to review some test shots - zoom in on faces and make sure they're not too light or too dark. If they are, use EC to adjust things and re-try.
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Old Dec 15, 2009, 1:13 PM   #8
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thanks TCAV and JohnG...I'll start taking some practice shots at home indoors and low light to see what I get and then make some adjustments.
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