There are two reasons I would use a fast shutter speed.
The first is to stop action.
The other is if I want to use a wide aperture to reduce depth of field. In the really old days we had a table called Exposure Value. It went from EV 1 to, I think, EV 22. Let's say my meter says I need to use EV 8 to properly expose a picture, and EV 8 could be...
1 second at f/32
1/2 second at f/22
1/4 second at f/16
1/8 second at f/11
1/16 second at f/8
1/32 second at f/5.6
and so on and so forth.
Now I have a decision to make: do I want to stop action, which would call for a fast shutter, or to get lots of the picture from foreground to background in sharp focus? If I want stopped action, I use a wide aperture and fast shutter; for depth of field I do the opposite.
Generally a higher shutter speed such as 1/500 is required to capture the image of a fast moving object without a blur. Some cameras have an automatic setting for this.
fast.....slow would allow more movement to be captured.
You neeed to use a fast shutter speed to freeze any sort of action when you are photographing sports, action or even fast moving wildlife or birds. Usually well over 1/500th of a second. You may need to change your ISO setting to 400 to 800 if you want to use high shutter speeds, on not-so-bright days, that are overcast, cloudy or without sunlight.
Aperture priority lets you set the aperture you want and the camera sets the shutter speed for you. You use it when you want to control depth of field. Shutter priority lets you set the shutter speed you want and the camera sets the aperture for you. You use it when you want to control how motion is rendered in the photograph. Program mode sets both shutter speed and aperture for you. Use it when you are not concerned with aperture or shutter speed control.
when taking pictures of something that is moving quickly for example birds
Shutter speed has a lot to do with your overall exposure. A higher shutter speed will decrease the light a lot. I was in best buy playing around with a camera and turned the camera shutter speed to 1/4000. After taking the photo, the preview was black. I realized it was because of how much higher I increase my shutter speed. Shutter speed also affects motion in a photo. A higher shutter speed will freeze all action in a photo a will less likely have a blur to it if you have a shaky hand. A lower shutter speed lets in more light while the shutter is will opened so the entire time that the shutter is open, the camera takes in all that light. Increasing chances of blur, you can also use this for crazy, funky effects! If your taking a picture of a waterfall with a low shutter speed, your gonna get a blur, which can typically look pretty epic sometimes too.
Shutter speeds determine the length of time that the shutter is open, and that the film or sensor receives light. If I wanted to freeze the motion of a speeding car for example, I would need to have the shutter open for a very short period of time. If I wanted to show that the car is moving, I would leave the shutter open for a bit longer. Many different effects can be achieved by changing the shutter speed.
Use a short shutter speed or in a dark environment, illuminate the object for a short time while the shutter is open. (look up Harold Edgerton on the internet to see what that pioneer of high spped photography has accomplished)
It depends on where you are seeing this number. Most shutter speed conventions do not use o1/12.5 of a second as a shutter speed; the closest would probably be 15 meaning 1/15th of a second, which is a very long/slow shutter speed usually producing blurs if you're not using a tripod. I can't think of a camera with that as a preset shutter speed but your camera might. You may possibly be looking at an intermediate f-stop (between 11 and 16) being reported on your screen or wherever these are shown (your LCD?) when you are in shutter priority mode where you are setting a fixed shutter speed and then the camera automatically adjusts for f stop (aperture) based on WB and ISO and is sophisticated enough to report an f-stop between 11 and 16).
yes, it can. it depends on the lighting. you can use a larger shutter to capture colors, for example a sunset.
Use shutter priority mode (S mode on dial) or manual mode (M on dial) and then select the speed you want by using the dials.
Having a slow shutter speed will show motion. The shutter speed needed will vary from subject to subject so use trial and error to find the shot right for you. A shutter speed of 1/2 (a shot lasting a half a second) is a good starting point.