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Old Apr 28, 2006, 2:28 AM   #1
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I read a lot about shooting in either AP or SP, but what I'm wondering is when do you chose one over the other?
Also, if you have the camera set to this, in order to have it recommend the correct settings, I'm assuming you hold the shutter release down halfway?
I have the Kodak P850 and have read for days and days months on end and can tell you what everything means and does, but when it comes time to match my "book knowledge" to the real world of taking/composing a shot, I get confused and don't know what to use.
Any help is greatly appreciated!

Gina
Chicago IL
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Old Apr 28, 2006, 4:30 AM   #2
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Hi, Gina.

AP and SP are semi-automatic camera modes, i.e. you choose manually one parameter and the camera sets the corresponding parameter to get a correctly exposed image according to camera's light metering and ISO settings. Which mode to choose depends on your subject and the effect you are after. Generally speaking, aperture setting controls depth-of-field (DOF, a distance range where all subjects are in focus) and shutter speed controls movement.

For example, when you shoot a portrait you want your model's featuresto be sharp and an out-of-focus, blurred background. So in AP mode you set aperture to low F-numbers (F2.8, F3.5) and when you half-press the shutter button your camera sets focus and the appropriate shutter speed.

In close-up and macro you want DOF as large as possible, so again in AP mode you set aperture to high F-number (F8, F11) to get as many details as possible in focus.

If you shoot a motorace and want to get a sharp picture without motion blur you set a high shutter speed (1/500, 1/1000 sec) and the camera sets the appropriate aperture.

If you want to get a dreamy silky effect when you shoot a waterfall, set your shutter to a slow speed (1/30, 0.5-3 sec). To avoid a camera shake you can use a tripod.

With image stabilization you can get sharp pics while handholding your camera with relatively slow shutter speed (~1/20 sec).

If you set one parameter (aperture or shutter speed) and the camera can't set the correct corresponding parameter, or it's out of camera's range, you usually get some kind of warning in a viewfinder or LCD.

HTH,

Alex

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Old Apr 28, 2006, 7:50 AM   #3
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Good explaination Alex. I'd add one more: for general shooting setting aperture priority with the aperture set one or two stops down from wide open generally gives the sharpest image.
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Old Apr 28, 2006, 9:12 AM   #4
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Great info, guys. Like Gina, I am a newbie and have read lots about shutter speed, app priority, iso, etc and have some understanding. But like Gina, translating it into each situation can be confusing. Those examples are a great help!! I just got a new km 5d and am looking forward to learning!! Thanks! And good luck Gina!!

Darlene
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Old Apr 28, 2006, 9:49 AM   #5
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gina4xoxoxo wrote:
Quote:
I have the Kodak P850 and have read for days and days months on end and can tell you what everything means and does, but when it comes time to match my "book knowledge" to the real world of taking/composing a shot, I get confused and don't know what to use.
Any help is greatly appreciated!

Gina
Chicago IL
Gina,

Alex had a great explanation - nothing to add to that part of it. But, my advice is to practice while you're reading. Take the same shot at different apertures and then upload to your PC and view results (lcds on cameras are too small to really see what's happening). Do the same type of exercise with different subjects. That's the best part of digital is you can get fairly instant feedback and you can start to get a feel for how your particular camera works at the different apertures. Then do the same thing with shutter speeds and moving objects to see how shutter speeds affect the things you shoot. But, the key is to get the images back to your PC within the same day so you still remember how the object/scene looked to your own eye. In short order you'll start to have a feel for what apertures/shutter speeds will give you certain affects. It's a lot like driving - the only way to learn it is to do it with a lot of repetition and in a somewhat controlled manner. That's my two cents

Best of luck!!
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Old Apr 28, 2006, 11:05 AM   #6
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One difference between shutter and aperture priority is that with aperture priority you are always shooting within the capabilities of the camera and you can easily exceed those capabilities with shutter priority.

For action photography where you want the maximum shutter speed you normally use aperture priority and not shutter priority. If you open the lens all the way in aperture priority the camera is generating all of the speed it can for a given light and ISO setting. You can half-depress the shutter to see what that maximum speed is and make decisions about whether you have to raise the ISO. As you get close to maximum shutter speed the camera can usually adjust in smaller increments than you can set in shutter priority even if you wanted to go though the hassle of finding your maximum shutter for a given situation. You can set a speed too high for the available light and maximum aperture in shutter priority but you can't do that in aperture priority.

The same can be true but to a lesser degree for slower shutter speeds to give speed blur, softening of water etc. The camera will let you set 1/10 second on a bright sunny day and show minimum aperture. Many don't give a warning that it is a dumb setting to use because the camera can't stop down enough to not burn out the photo. Again, if you use aperture priority with the smallest aperture and lowest ISO, the camera will generate the slowest shutter it can for the situation. If that still doesn't generate a speed slow enough you know you have to go to a neutral density filter the get the speed you need. If you have a good feel for the light and are good with a live histogram you can use shutter priority, but aperture priority is usually better for generating the slowest speed your camera is capable of.

Most non-DSLR cameras anymore have modes specifically for all of those situations. They have portrait modes that give maximum background blur. Some portrait modes also enhance the skin tones, so purists might want to use aperture priority instead. Most have sports and action modes to maximize your shutter speed. My little pocket camera has a "Soft Flowing Water" mode that engages the internal neutral density filter, so it does better than you can yourself for slower shutter speeds.

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Old Apr 28, 2006, 12:11 PM   #7
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Thanks for the info everyone.


slipe

Thanks for the added info. I've always thought that to get a blurred waterfall you have to use shutter priority. The waterfall I'm planning on capturing is outside, not secluded among trees, so light-washout is a concern.

I don't have an ND filter yet, and I had planned on capturing a waterfall using negative Exposure Compensation and Shutter Priority. I'll be sure to give Aperture Priority a try.

Thanks.

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Old Apr 28, 2006, 1:39 PM   #8
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rey wrote:
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I don't have an ND filter yet, and I had planned on capturing a waterfall using negative Exposure Compensation and Shutter Priority. I'll be sure to give Aperture Priority a try.
Exposure compensation is designed to brighten or darken images compared to what the camera's meter thinks is needed for proper exposure.

Correct Exposure comes down to the amount of light, the ISO speed, and the aperture. A variety of combinations will produce identical exposure. You only need to use Exposure Compensation if you want a brighter or darker image compared to what the camera's metering would normally give you in the same conditions.

A +EV value gives you a brighter exposure. The camera uses a slower shutter speed and/or larger aperture to get a brighter exposure, compared to what the camera's autoexposure algorithms would have selected.

A -EV value gives you a darker exposure. The camera uses a faster shutter speed and/or smaller aperture to get a darker exposure, compared to what the camera's autoexposure algorithms would have selected.

So, if you tried to shoot using Shutter Priority mode with a -EV setting, the camera is going to use a smaller aperture than it normally would, resulting in underexposed images in many lighting conditions.

But, since the smallest aperture of the lens is limited by the lens design, once it reaches the smallest available aperture (highest f/stop number), it will start overexposing, with or without exposure compensation if you have shutter speeds set too slow.

Also, most lenses are going to be softer near their smallest aperture settings due to diffraction.


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Old Apr 28, 2006, 3:47 PM   #9
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rey wrote:
I don't have an ND filter yet

if you have a polarizing filter it can also be used, giving you additional 1.5-2 stops of exposure and not affecting the colour balance of your image.

One more thingisan old rule of thumb to determine the slowest shutter speed and to avoid a camera shake when you handhold it and shoot static objects.

shutter speed = 1/f, where "f" is a focal length of your lens.

This gives you pics with no blur caused by a camera shake at 1/30 sec and 30 mm lens and 1/300 sec at 300 mm, so beware those long telezooms very common on the modern light and compact cameras:-)

With IS you canuse slowershutter speed (up to about 2 stops).

Best wishes,

Alex

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Old Apr 28, 2006, 4:43 PM   #10
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JimC

Thanks for your description. I think I understand what you said.

In my case, I want to capture the motion of waterfall. My first instinct would be use a tripod and use Shutter priority and decrease the shutter speed. Now, assuming the water, or other objects in the shot turns out too white, I would then use -EV to compensate until I get the desired result. I would also increase or decrease the exposure time depending on how fast the water is flowing, and also the resulting "flowing" motion captured. Isn't this correct?

I've read somewhere, that the ND filter would only come into play if it's really bright and the -EV compensation is maxed out and yet I still get a washed out image. Is this correct? Or are you saying that the -EV is NOT a substitute for ND filter at all.

Unfortunately, we don't have any water fountain on any parks where I live, so I can't give this a try before going to a waterfall. But I'll look around on nearby cities to test this.

My main concern is that the waterfall I'm planning on capturing is not secluded and flows into the (Pacific) Ocean. So it will be very bright on a clear day.

Thanks for your help.

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