Ophrys Photography

Wildlife photography by John Devries, Kent UK. Inspirational images from nature.
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Photographing wild birds Part 3

In my first tutorial on photographing wild birds I said "The following is a list of the most frequent errors that I have noticed that people make when photographing birds" :

1) Subject too distant.
2) Subject not in focus
3) Blur due to subject movement - motion blur
4) Blur due to camera movement
5) Incorrect exposure
6) Little consideration given to lighting or composition

We covered the first issue in depth in the first tutorial and digressed a little into equipment in the second tutorial. So let's get back to moving on down the list to find counters to the common errors.

2) Subject not in focus

Firstly we need to separate this from other causes of image blur such as motion blur and camera shake. What we are talking about here is failure to obtain critical focus either by limitations in autofocus or our own failure to accurately focus manually on the subject.
When I talk about an image being critically sharp or critically in focus, I mean that it still looks sharp when viewed at 100% or "Actual pixels" when viewed on the computer.

Failure to use correct focusing mode - single shot or AI servo.

I am often amused to see people trying to photograph birds in flight in One Shot mode and wondering why everything shot is out of focus.Let's look at these modes (and some others) in more detail.

One shot focus.
In this mode, when the shutter button is pressed half way down the autofocus focuses on the subject and the camera beeps a confirmation (unless deactivated in custom functions). This is the mode generally used for static subjects.

One Shot can be slightly more precise than AI Servo, and is a bit more sensitive in low light, but it should not be used for moving subjects. This is because if the subject moves after locking focus you will get a blurred shot. If this happens you would need to take your finger off of the shutter release button, and then half-depress it again, to regain focus.

Many people use this mode to focus and recompose the shot if their subject is off-centre in the frame. However, if you are using a lens with a very wide aperture (such as f1.4) or a telephoto lens with the subject large in the frame there can be enough of a difference between the original point of focus and the final composition for a focusing error to creep in and soften the shot.

Off- centre subjects are much better handled by doing the reverse of focus and recompose - that is to compose and move the autofocus point over to the subject. Cameras with advanced autofocus systems have more AF points to choose from (45 points plus) compared to lesser models which typically have as few as 9 AF points.

If the tail of a bird goes out of focus but the eye is still sharp, the human brain can accept that as being a natural thing. If the eye is not sharp you might as well bin the image. So: When photographing static birds I always move the autofocus point over to the birds eye.
This takes a few moments to do but it is time well spent. If the bird is large in the frame and you focus on the centre of the bird with a fairly wide aperture, there may not be enough depth of field to get the eye in focus. If I had used the centre point on this puffin, the shoulder would have been sharp and the eye soft. Note the 9 AF points of the Canon 40D that was used to take this shot.

AI servo and AI focus (Continuous focus on Nikon)
This is the mode you should use for moving subjects for example a bird in motion on the ground or in flight.

Focus and recompose does not work in AI servo mode as the camera continually tries to refocus on a subject as it is moving and tries to predict where it will be just before it takes the next shot.
You have to select an autofocus point if the subject is off centre otherwise the camera will focus on the wrong part of the subject. With a bird that is large in the frame, the eye is usually off-centre, so you will need to get used to moving AF points around. On most cameras you have to press the Autofocus select button that looks like this:

You then either scroll to the point you want to select with the main and quick control dials or the multiselector button (joystick).On some cameras you have to to assign this function to the multiselector button in the custom functions. Usually a prod on the multiselector returns you to the central AF point.

Although you must use AI servo for a moving subject, there is no law that says you have to use one shot mode for static subjects. Birds rarely keep still and you don't know when they are going to give you some action to photograph, so I always use AI servo when photographing birds regardless of whether they are still or moving.

AI focus is available on some cameras and is meant to offer the best of both worlds by acting like one shot mode but commencing tracking when a subject begins to move. Unfortunately it is not very reliable and most people, myself included, prefer to use AI servo.

Automatic focus point selection (AFPS)

In this mode, which can usually be accessed by moving the AF point selector right over to one side of the viewfinder and beyond until all the outer AF points light up. You might have expected all the AF points to light rather than just the outer ones to indicate that all 45 points are active, so this mode is often nicknamed the "ring of fire" which describes it rather well.

The way to use the ring of fire (AFPS) is to focus on the subject with the centre AF point and give it about a second to lock on. You then try to keep the focus point on the target and the camera is meant to hand-off the focus to adjacent points to maintain focus. The trouble is, in my experience the system does not work totally reliably and I find that often the camera will focus on a high contrast part of the subject such as the bird's wing rather than the intended bit - it's head. AFPS works pretty well for birds flying against a clear sky, but often loses focus if the background gets busy (trees and bushes).

Centre point vs point expansion

With some cameras you can expand the focus points to include a cluster around the selected point. On a fast moving subject it can be a lot easier to keep the cluster of focus points on the target than by just using a single point. However, the central focus point is usually the most sensitive one and if you are skilled enough to keep the dot over the target it is often the most accurate method of focusing and the one I tend to use most.

Breezebrowser Pro can show the active AF point superimposed onto RAW images (but not TIFF or jpegs) Below is a cropped shot of a gannet in flight with the central AF point bang smack on the eye - just where you want it to be. The image was taken with a 1 series Canon camera - note the 45 AF points. If you get an out of focus image it is worth checking to see if you did actually nail the focus like this one. If the camera repeatedly misfocuses despite the AF point being on target you may have a faulty camera.

In the next image, an off-centre AF point was selected for this kingfisher. Notice that with even 45 points to choose from, there was still not one that I could put exactly over the bird's eye. In actual fact, the AF points are bigger than the boxes displayed in the viewfinder, so the eye was still probably covered. This is close enough - even if a wide aperture (shallow depth of field) is employed.

Back button focus

This is an advanced AI servo technique in which you reassign functions to the camera buttons, so the shutter release button no longer causes the camera to autofocus but it still meters the scene and takes the picture when you fully depress the button. Autofocus is assigned to another button on the back of the camera such as the star button (hence back-button focus) so that the photographer needs to keep his/her thumb on the star button for AI servo to work. Take your finger off the star button and the focus is locked wherever it last focused. This emulates being in one shot mode again. Latest cameras have an "AF ON" button on the camera back and you can use this to either start or stop focus according to the camera custom function set .I have my Canon 1DmkIII set to Cfn IV,1,1 which makes the camera behave as usual but stops AI servo if I press the AF ON button.

Back-button focus is very popular with sports photographers and is very relevant to active birds that continually alternate between moving around and standing still. Waders feeding on the sea shore spring to mind. If you fancy reading more and trying it out, click here.

Manual focus

Autofocus is wonderful but there are occasions when it just won't work and you are better off switching it off. These situations include very low light situations, very low contrast subjects and when a bird is partially obscured by twigs or grass (So the AF wants to focus on the twigs instead of the bird).

On these occasions it is best to switch the AF button on the lens to OFF and focus the lens manually.

There are occasions when I like to manually focus. The commonest occasion that I prefer to focus myself is when trying to photograph a bird taking off or landing on a perch. By pre-focusing on the bird or the perch and then switching AF off on the lens, this can be far more reliable than the autofocus system which simply cannot respond fast enough. I used this method to take pictures of bee-eaters in Hungary when they repeatedly landed on the same perch. I set the cameras to live view and focused manually on a perched bird. Then, using a cable release I simply watched for the bird to return again via the rear screen and machine-gunned it with the motordrive on my 1DmkIII . This was the result:

Other causes of out-of focus images

If the image looks blurred through the viewfinder and the camera is not focusing, you may have accidentally knocked the lens Autofocus on/off switch into the off position. This is not as daft as it sounds .I find that with certain lenses - particularly my 70-200 f 2.8 L this happens pretty much every time I take it out of my bag. This is a silly design fault. You often see pro sport and photojournalist photographers with black tape on their lenses for this reason!

Another reason for out of focus images on certain lenses is that the focus range limiter switch has been set to wrong range. If you have been photographing birds in flight with the distance limiter switched to 16.2m to infinity and then you try to photograph a bird on a post at 10m the camera can't achieve focus. This is easily done - as I can testify !

Typical Canon lens switches - the top one is the focus limiter.

Also, if you try to focus on a bird's head when it is really close, you may be a bit closer than the camera's minimum focus distance. If you want to get closer than the normal focusing distance you can achieve this by fitting an extension tube. (A tube with no optical elements). The ring-billed gull below is a rare migrant from USA that turned up in the UK in Kent. It was very confiding and I was able to fit an extension tube to my 500mm lens to get close enough for this head shot:


Canon 1DmkIII autofocus guide

This camera has had a checkered history with autofocus performance in AI servo mode, but in its latest guise with all free updates and latest software I find it autofocuses very well indeed.Les Zigurski has written an extensive guide to setting up this camera's custom functions that I won't attempt to emulate, so if you use this camera and would like to read more, you will find this link invaluable : Les Zigurski