Focus Modes &

Exposure Modes

Focus ModesTo get the best results and sharpest images, it is important to select the correct focusing mode for the situation.

The decision is based upon whether the subject is static or moving.

It is also important to select the focus point or area which is going to be appropriate.

You will find that you will have a default “go to” setup which suits your style and type of photography and it may be the case that other modes do not get used often, if at all.

Focus Modes

Normally, the camera has four basic focusing modes. Most cameras label the modes the same way but there may be exceptions.

● AF-A - Automatic Selection Auto Focus

● AF-S - Single Auto Focus

● AF-C - Continuous Auto Focus

● MF - Manual Focus

Auto Focus AF-A

This is normally the default mode that the camera is set to when it is shipped to you. It’s an “intelligent” mode that will detect whether a subject is moving or static and select either the AF-S or AF-C mode for that shot.

As with other intelligent systems on your camera, it is dumb and can quite possibly choose the wrong mode when you least expect it.

It is probably not advisable to use it as selecting the mode yourself will be more accurate.

Auto Focus AF-S

This is the mode that you will be using the most. When you press the shutter button down halfway, it will focus on the subject that is covered by the focus point(s).As long as you keep the button half pressed, it will stay on that initial point.To refocus, release the button and press halfway again and it will focus on that particular point.This is the mode that you will almost certainly use unless you need to track a subject that is moving fairly quickly.

Auto Focus AF-S

The good point of single AF is that you can focus and re-compose.

If your subject is not in a focus area or it is too much of a hassle to select a focus point, you focus on the subject, hold the button halfway and then move the camera to re-compose the shot and then press the shutter fully.

On most cameras, the holding of the shutter button locks the focus but there may be ways to reconfigure this behaviour on your camera.

Auto Focus AF-C

Continuous Auto Focus is the mode to choose if you have moving subjects.A half press of the shutter will activate auto focus and whatever is covered by the focus points will be selected.Holding down the button halfway will keep focusing on that subject even if it moves but it must be covered by the focus point at all times. If it jumps outside then it will lose focus as a default action.You cannot recompose the shots as the focus will not lock.

Manual Focus MF

Manual focus is used to fully disable any auto focus system. In the camera menus or switch on your camera body, it overrides any switch on the lens itself.

To focus when in this mode, you need to turn the focus ring on the lens.

Use it so that you have a continuous focal length. For instance, if you wish to do a panorama or multiple shots for HDR or focus stacking.

Manual Focus MF

You can focus using any other mode and then switch to Manual Focus to ensure that you are at the desired point.

If your lens has an AF/MF switch, it is easier to use that than using on camera functions.

Remember that if you adjust your positioning or zoom, you will need to refocus to ensure correct focus and sharpness.

Manual focus is ideal when it is difficult to obtain focus (i.e. low light, lack of contrast)

How To Focus

It is important to get the focusing right to make sure that your subject is sharp. The lower the f number used, the shallower the depth of field and the more important it is to get the correct focusing point.

In general, make sure that your main subject is covered by the focus point or area and press the shutter button down halfway.

Recompose if necessary (for instance to move the subject onto a third) and then fully press the button down.

How To Focus

Different cameras have different way of determining focus but in general terms, the camera needs a good bit of contrast to be accurate.

Plain textures, darkness and reflections can confuse the auto focus system so try to focus on a point that is clearly visible and has a difference in light or texture. In darkness, find a lit object around the same distance away.

When taking portraits, always focus on the eyes. Sharp eyes are essential for good images. Use the closest eye if the subject is at an angle.

“Back focusing”Some cameras enable you to configure a button to take over the control of focus from the “half press” of the shutter button.

Normally it’s a button on the back of the camera (hence the “back focusing” name).

By removing the control of the focus from the shutter button, it enables you to focus when you desire rather than have the risk of the camera refocusing as you press the shutter button.

It also saves you having to hold the shutter button halfway whilst recomposing or waiting for a shot.

Focus Area ModesAfter choosing your AF mode, you will need to choose the area or point where focusing will occur.Every camera labels them differently, but as a general rule they work in a few basic ways.

● Auto area - Automatically chooses ● Single point - You choose one point ● Dynamic point - One point but looks at adjacent

points

● Tracking - Follows subject across viewfinder

Auto Area Focusing Mode

This is the default mode that cameras come shipped with. It’s an “intelligent” mode.

Generally, it will focus on a subject that is relatively close to the centre of the viewfinder and closest to the camera. It will assess the scene and try to guess what you want in focus.

With your camera on Auto, it will also adjust Aperture to try and get the correct depth of field.

As with any auto or intelligent modes, you don’t have a lot of control.

Auto Area Focusing Mode

When you look through the viewfinder, you will see a number of dots light up when the button is pressed halfway. These will indicate the points on the image that are in focus.

It can be useful when you need to do quick snaps but may be unreliable and not focus on the subject that you wish to.

It tends to be the least used of the focus area modes but it will normally be selected when you place the camera in an Auto mode.

Single Point Focusing Mode

This will make your focus area a single point which is movable.

When looking through the viewfinder, one point will light up when you press the shutter halfway and that is the point where the camera will attempt to auto focus.

This gives you precision over what the camera is focusing on.

If you are photographing static scenes, this is the recommended mode to set your camera to.

Single Point Focusing Mode

Every camera is different and will have different ways of moving the point around the viewfinder.

Normally, after half pressing the shutter and releasing, the point will be active for a short period of time and you can move it using the directional pad on the rear of the camera.

You will see the highlighted spot moving around the available points on your camera.

When the point is active, usually pressing the OK or Back button will return it to the centre.

Single Point Focusing Mode

Most cameras have many focusing points, mainly grouped towards the centre.

The most accurate and therefore favourable are closest to the centre, the very centre being most accurate.

Moving the point consumes time and therefore the “hold and recompose” option may be more desirable using the centre point.

Remember to reset to the centre point to avoid focusing errors later on.

Single Point Focusing Mode

When using the Single Point in AF-C mode, the camera will always be focusing on the point that you have selected.

It will need to follow the moving subject at all times and if the subject goes out of that point and into the next one, the camera will attempt to refocus on whatever may be in the original point.

Normally that will be the background and it will result in out of focus shots. It takes time to focus at different distances.

Dynamic Point Focusing Mode

The Dynamic Point mode is mainly used when in AF-C mode.

It acts like the Single Point mode with the exception that it looks at the surrounding points as well.

If a subject strays outside the main point, it will use that next point as a focus point, hoping that you will move the original point back over the subject by panning the camera.

It’s a little more forgiving than the Single Point mode and is good for erratically moving subjects.

Tracking Focusing Mode

This is the go to mode for action photography and will almost certainly be used in AF-C mode.

When you press the shutter button halfway, it will use whatever is at that point as your subject but it will track the subject around the viewfinder as best as it can.

As long as you keep the subject in the viewfinder, the camera will attempt to focus on it.

If it goes outside the area of focus points, you will need to repeat the process.

Tracking Focusing Mode

Once again, the points near the centre are the most sensitive for this type of focusing. The points are often known as cross type focusing points and they are best at tracking movement in 3D.

Shoot wide and crop in later to make sure that your focus is maintained.

It is best to team this method up with burst shooting modes to ensure that you get that good shot but be prepared for a lot of images and reaching the buffer limit of your camera.

Autofocus Combinations

In general, you’ll be sticking to certain combinations or AF mode and AF area modes.

● AF-S and Point for general photography

● AF-C and Point for general movement

● AF-C and Tracking for fast action panning

● AF-C and Dynamic for slow action panning

● MF for difficult situations and constant focus

● AF-A and Area if you’re lazy or don’t care!

Metering ModesYour camera is equipped with a number of modes to control how it measures the amount of light entering through the lens.

Choosing the correct option can get better exposed images in different lighting situations.

Knowing how your camera reacts to different scenes is key to getting a properly exposed image.

Exposure errors can be corrected in post processing but, as with everything, it’s better to get it right in camera and save the time, effort and difficulties later.

How the Camera Measures Exposure

In basic terms, the camera is trying to achieve an average exposure across the measured area. This value is a Neutral grey that reflects back 18% of the light.

In RGB terms, it’s 128, 128, 128 or midway between pure black (0, 0, 0) and white (255, 255, 255).

As cameras are more advanced, the camera will try and determine the type of scene and skew the value to get the best result.

Metering ModesEvery camera has different labels for their metering modes but in general, it boils down to three basic modes. Canon and others may have a fourth. These are:

● Matrix or Averaging Metering

● Centre Weighted Metering

● Partial Metering (Canon)

● Spot Metering

Metering ModesThese metering modes are independent of the focusing modes, they are not the same.

The only thing that are linked (on most cameras) are where the metering is going to take

place. The selective metering modes will normally base their calculations around the focus point selected.

There may still be times where you will need to use exposure compensation to adjust the exposure manually.

Matrix or Average Metering

This is the default camera mode for Nikon. Most cameras will take an overall view of the whole scene in the viewfinder, make calculations and adjust the exposure based on that.

It’s quite sophisticated (and gets more sophisticated as technology develops) and will often detect and adjust for various scenes to prevent too many occurrences of over or under exposure.

It can sometimes get confused and make dark scenes too light or light scenes too dark.

Matrix or Average Metering

As you use your camera, you’ll get to know how it behaves under certain conditions. It may work pretty well in the dark or it may not. Manual adjustments will become second nature.

For instance, in a heavily wooded area with the dark greens and browns, it may well over expose the images, so a little negative compensation may be needed.

In the snow or overcast conditions it may produce a dull, under exposed image so a bit of positive compensation may be required.

Matrix or Average Metering

Area covered by Matrix or Average Metering:

Centre Weighted Metering

This is similar to the Matrix or Average mode but it is weighted towards the centre of the image (around 40-50%) but it takes into consideration the outer areas.

It is useful when the main subject is surrounded by light or dark and will adjust the exposure accordingly.

If you are using a different focus point, it should be centred around that point.

Centre Weighted Metering

For instance, if you are taking a picture of a cottage with a bright sky and green grass surrounding it, it will make the decision based on the cottage and largely ignore the grass and sky and should give a more balanced exposure.

Another example may be a car against a dark background. To prevent over exposure, use Centre Weighted and it will largely ignore the dark background.

Once again, exposure compensation can be used if the image is too bright or too dark.

Centre Weighted Metering

Area covered by Centre Weighted Metering:

Partial Metering

This mode is a feature of Canon (and some other) cameras and limits the metering to an area around the focus point of around 30%

It is useful for accurate metering of a fairly large area and would be ideal when used for head portrait shots where a Caucasian skin is roughly the same 18% grey that is measured.

It’s good in high contrast scenes where a bright or dark background would interfere with centre weighted and matrix or average metering.

Partial Metering

Area covered by Partial Metering:

Spot Metering

This bases the exposure calculations on a very tight spot around the focal point (around 10% of the image) and is ideal for getting the best exposure for a small part of the image.

If there is a lot of contrast or large areas of dark and light, using the spot focus metering on an area of mid tonality will ensure that only that small part of the image will be sampled.

You have to be careful to use it correctly as it will not evaluate any other area.

Spot Metering

For instance, sampling skin on a portrait will give the correct exposure for that part of the body and ignore the rest. Ideally the face.

Using it on a wall being lit by a street lamp will ensure that the extremely dark and light areas are ignored and give exposure of the wall.

Sampling a fully white area and then adding +1 to +2 compensation will make sure that the white is correctly exposed. Sampling black and using -1 compensation would ensure that the black is correctly exposed.

Spot Metering

Spot metering is the most accurate and can be the most flexible with a bit of work and is good where you want to ensure that certain areas are exposed the way you want them to. It works in isolation of the surrounding area.

It is advisable to use only in those situations where the other modes would not give good meter readings.

Using spot metering in general scenarios would give a huge degree of fluctuations depending on the sampling point.

Spot Metering

Area covered by Spot Metering:

Metering Modes Sample ImagesEach of the Metering modes were selected for the same scene.

It’s a very high contrast scene to emphasise the differences in the modes.

A central Single Point focus was used and that is where the exposure was based around.

These are the results of an un-processed RAW file with no adjustments made.

Matrix or Average Metering

Red:

231

Green:

231

Blue:

231

Centre Weighted Metering

Red:

185

Green:

185

Blue:

185

Spot Metering

Red:

155

Green:

155

Blue:

155

AE Lock (AEL)A lot of cameras have an AEL button or AE Lock. It can often be configured for other functions and it can be changed from an on/off toggle or a press and hold button.

It enables you to lock exposure in all modes other than Manual.

You sample the exposure by half pressing the shutter, press or hold the AEL button, recompose the image, press and hold for focus and then press the shutter.

AE Lock (AEL)It is an ideal solution for when your focus points and exposure points are in different locations.

Some cameras activate AEL lock when the shutter is pressed halfway down but most can be

configured in a way that the function can be turned off.

Some cameras allow you to change the button to activate Auto Focus lock (AFL), AE Lock (AEL) or both (AFL+AEL).

If not, you can always use Manual mode.

Exposure Modes in Manual

If you are using Manual, the exposure metering modes will not adjust your exposure but will reflect the indications in the exposure meter bar on your viewfinder.

You will need to adjust Aperture, Shutter Speed and ISO to get the correct exposure. It will only affect the area that the meter is using to measure the light.

You can sample various areas of the scene to get an idea of the overall exposure and then change the values to get the result that you desire in much the same way as adding exposure compensation.

Final Words

Remember that you are capturing moments on your camera. That is more important than the technical side of things.

Don’t get bogged down in settings, changing modes, moving focus points etc. when what you could be getting will be gone in an instant.

If you have time, get it right in camera and the results will be better after processing. If not, shoot away, even in an Auto mode to make sure that you capture the moment.

Final WordsLearning how your camera reacts in certain situations will make it easier. You will know its quirks and foibles and be able to react to them quicker or to predict what it is going to do.

Learn when it is likely to under expose or over expose and adjust accordingly. Most of the time, you’ll not need to change modes to get the right result but be prepared and know when to change them.

Remember that focusing is much more important than exposure. Exposure can be adjusted to a degree in processing. Focusing can’t

Final WordsDon’t get frustrated if you don’t understand certain concepts. They will have a “penny drop” moment when it all comes together and you realise what the hell that mumbo jumbo meant all those months ago.

Practice before you need to do it. Take photos at home, in the garden, experiment. That’s the best way of learning.

It’s a hobby. Have fun with it. Look back over the years and see how you’ve developed (excuse the pun) as a photographer. Capture the moments, create the art, enjoy photography.