Shooting Modes

Your camera has four primary shooting modes, which differ in what parameters you can control and which are calculated automatically (and how):

The shooting mode is set by a dedicated dial (often called the PASM dial) on most Four Thirds cameras, or by using a button+turn on the E3.

Aperture Priority Mode

Other than brightness, aperture controls the depth of field (DoF). Aperture priority is therefore most used for the following reasons:

• Portraits: benefit from a shallow DoF and thus a large aperture
• Macro: generally wants deep DoF and a small aperture
• Low-light photography: selecting the largest aperture in order to get the fastest shutter speed available.
• Optimizing sharpness by using the lens's sweet spot

The first two are the most important ones, and are discussed on one of the next pages where I go into Depth of Field in more detail. Suffice to say for now that the larger the aperture, the shallower the depth of field.

Low-light photography

A larger aperture means more light falls on the sensor, which means you can use a faster shutter speed to get the same exposure. This is why lenses with relatively large apertures are called "bright" or "fast" lenses. This is a boon in low-light photography, where you want to use the fastest shutter speed available to minimize blur without having to up ISO too high (which introduces noise). To ensure you're always using the fastest shutter speed available, use aperture priority mode and set the aperture to a large value. Keep in mind that using a large aperture decreases your depth of field, so you may not want to use the largest available (but in many cases, you do).

Lens Sweet Spot

While Zuiko Digital lenses (and especially the Pro and TopPro lines) have a reputation for excellent sharpness "wide open" (using the largest aperture), most lenses have a "sweet spot" which is the aperture where they are sharpest. Usually this will be one or two stops below the maximum aperture at a certain focal range. Many lens reviews will point out what according to them is the sweet spot and what apertures should be avoided. For four thirds, the consensus is to avoid shooting smaller than f/11 unless you need the Depth of Field, due to diffraction issues.

Shutter Speed Priority Mode

Shutter speed priority is generally used when one desires control over motion blur. Motion blur occurs when either the camera or the subject moves during the exposure. The faster the shutter speed, the shorter the exposure and the less motion blur there will be.

• To get the maximum depth of field while still maintaining a minimum shutter speed (to prevent motion blur)
• Sports photography, to avoid motion blur
• Special cases where you want motion blur
• Astrophotography

When motion blur is desirable

In most cases motion blur is something to be avoided, but it can also be used for creative purposes. A typical example is the "dreamy waterfall" effect where a long exposure of  a waterfall is made to create streamers of water. Similarly long exposures are sometimes used for night shots of roads to give ghost tail-light trails.

Handholding at low shutter speed

The general rule of thumb is that without image stabilizer you need a shutter speed of at least 1 / (Focal Length*2) to avoid motion blur due to camera shake. So if you're shooting with the ZD50mm you'd want at least 1/100 second shutter speed. With IS this may go down considerably. Of course, this number depends on the photographer with some needing faster speeds and others being able to cope with far less. Either way, you can use shutter speed priority to set the speed to a value you're comfortable you can handhold.

Note that no matter how steady your hand is, you will still get motion blur if your subject moves too fast.

When there's too much/too little light

While in aperture mode the camera will nearly always be able to select a shutter speed to get the exposure right simply because the range of shutter speeds is so large (generally from 1/4000sec to 4sec, which is about 14 EV). This is not true in shutter speed priority mode because the available range of apertures it can choose from is a lot smaller (depending on the lens, but at best f/1.4 to f/22 which is only 8 EV).

If there's too little light, the camera will flash the maximum aperture of the lens in the viewfinder and on the LCD to indicate that your shot will be underexposed. You should then select a slower shutter speed.

If there's too much light, the camera will flash the minimum aperture of the lens (generally f/22) to indicate the shot will be overexposed. You should then select a faster shutter speed.

Manual Mode

M-mode lets you set both aperture and shutter speed. Unless you're using auto-ISO, this means that you have full control over the exposure (and that any exposure bias you enter is ignored).  Using manual mode from scratch needs a fair amount of experience, but there's some cases where you want to switch from one of the other modes to manual to keep exposure constant between frames (for example when shooting panoramas). In these cases you would copy the settings the camera calculated in the other mode over.

When using a camera with two control dials (E-1, E-3, E-30) one wheel will be set to shutter speed and the other to aperture (which is which you can chose for yourself in the menus). With other cameras by default the wheel controls the shutter speed and you need to press and hold the exposure compensation button and turn the wheel to change the aperture.

In manual mode, the camera will display how much your exposure differs from the measured amount in EV using the exposure bias display. If this number is 0 then your settings match the metered exposure. If the number is blinking (at +5 or -5) it means your exposure is so bright or dark it falls outside the normal exposure bias range.

Program Mode

I have left program mode for last despite it being the most automatic of the four modes (and the first one on the dial). The reason is that while program mode may be the easiest to use, it's the hardest to explain. When using program mode, the camera will calculate both aperture and shutter speed. To do so it uses a special algorithm or "program". The program attempts to:

1. Get your shutter speed to 1 / (Focal Length*2) to avoid camera shake
2. Maximize your Depth of Field by shrinking the aperture
3. Avoid the higher apertures

For example, say you're using the ZD 50mm in good light. The program first selects 1/100s as the shutter speed. It calculates what aperture would go with that and gets f/16. This runs foul of rule 3 up there so instead it increases the shutter speed to 1/200s and aperture to f/8.0.

Program mode is good for general photography when you don't have any specific artistic effect in mind but want to optimize sharpness by both avoiding motion blur and optimizing depth of field.As such it's equally suited for snapshots as for any case where getting the picture is more important than controlling exactly how it looks.

Program Shift

By turning the control wheel (if you've set it up for that) you can adjust the program by "shifting" it either left or right. Shifting the program changes the importance each of the rules above has. In practical terms: shifting the program left will give you larger apertures (and thus faster shutter speeds) while shifting it right will give you smaller apertures (and slower shutter speeds).

Program shift is useful when you know you're better or worse at handholding the camera than the program thinks, or if you want to quickly get more depth of field/less blur without switching to one of the other modes.

Program shift is reset when you turn the camera on or off, or when you switch to any of the other modes and back again.