Learning to Use Camera Modes
In previous posts I have been talking about how to take control over your digital camera, rather than letting the camera control YOU.
This knob here is where you exert that control! Note that it isn’t set at the green “AUTO” mode - which is the mode for newbies.
Most of those other modes which are marked by symbols are also for newbies. They are meant to simplify things by allowing you to set an exposure mode optimized for some common type of subject matter. Like for instance: the head setting for portraits and so on.
In the picture here, the camera (which is my old Canon Powershot G2) is set at Aperture Priority mode. What that means is: the camera allows YOU to choose the aperture you like - then the camera tries to set the shutter speed to a value which balances that choice to make a correct exposure. I may also choose to include the ISO-setting as another variable which I allow the camera to play with, to get the exposure right. If so, I set the ISO to “Auto” (which is done in a menu not shown here).
Aperture Priority means precisely that - I am about to make a shot in a situation where the aperture setting is the most important one - the one I particularly want to control for getting the result I want.
In a previous post, Using Aperture For Creative Control, I gave you a few examples, like the image of a spiral staircase shot from below. In that picture, it was important to get everything in sharp focus for best effect. And how do you do that? Yes, by using as small an aperture as possible. (Remember: smaller apertures have larger numbers - like, f=2 is a large aperture, ie. a large opening; while f=16 is a small one.)
The smaller the aperture, the larger is the depth of field you get - remember?
Conversely, in some situations you prefer to have a sharp focus on a special subject of interest only, and make some other stuff in the background be blurred - thereby less distracting. Then you want a large aperture. If you set your digicam in Aperture Priority mode, you set yourself in control over these things. You concentrate on what’s important and let the camera do the rest.
OK, over to the next important setting on that camera knob: Shutter Speed Priority. (Marked “Tv“; T as in Time.) Here, you want total control over the shutter speed, ie. how long time the shutter stays open. Typically, this is important to control in situations where you are dealing with a moving subject - I usually take the example of a speeding car (or speeding fish), as in my previous article, Using Shutter Speed to Get Image Control.
By setting the camera to Shutter Priority, you make that your priority for creative control in a particular situation. - In the picture of a speeding police vehicle here, the photographer has used a moderate shutter speed like maybe 1/125 of a second while panning with the subject - thereby getting the background blurred (motion blur) and creating a feeling of movement.
Fast-moving subjects may require very fast shutter speeds, ie. short exposure times, to be rendered as sharp. To get enough light into the camera sensor in that short time, the camera will choose a larger aperture. How large an aperture you can get depends on the lens. A “fast” lens is made of large discs of glass to achieve a large maximum aperture, thereby allowing you to use a shorter exposure time - and this is why it’s called “fast”.
Summing up:
Use Aperture Priority when the aperture setting is the most important for you - that is, when you want to control the depth of field; either by extending it or shortening it.
Use Shutter Priority in those situations where you need to control exactly what shutter speed the camera uses - like to “freeze” the motion of fast-moving subjects.
And, yes, there is another setting you can use, too: “M” as in MANUAL! Then you set both shutter speed and aperture to whatever you please. Back in the old days before automation became the order of the day, this was how you made pictures. You measured the light, with a separate hand-held exposure meter, and then decided on a combo of shutter and aperture settings which seemed to fit the situation, before actually making the exposure. Well, you get the idea…
Photo credits: police vehicle by extranoise.
