In my earlier tutorials
on photographing wild birds I have covered points 1 to 4 in my
list of common errors:
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
Let's now carry on moving down the list and finding counters to
5) Incorrect exposure
I should probably start by saying that there is probably no such
thing as incorrect exposure, as it depends on what the photographer
is trying to portray. In the first image below I exposed for the
background at the expense of the subject and in the right hand
image I exposed for the subject at the expense of the background.
There is no right or wrong here - it is your choice, this is where
your skill and artistic interpretation come into play. As it happens
in this instance I prefer the left image.
Despite what I have just said, what we are trying
to achieve in this tutorial is to learn how to get the classic
well-exposed shot of a subject without blowing out highlight or
Thanks to the accuracy of current metering systems and the ability
of digital cameras to preview a histogram of exposure immediately
after taking the shot on the screen on the back of the camera,
getting the correct exposure has never been easier than it is
today. If my subject allows me the time to do it, I
always get the camera set up in advance and take a few test shots
to get the exposure right before taking pictures in anger.
This is equivalent to a studio photographer in the days of film
taking a polaroid test shot before commencing a shoot.
Checking the exposure with the camera histogram
If you don't already use the camera's histogram
you should start immediately as it is the key to perfect exposure.
It looks a bit daunting at first, but trust me, it is easy really
and it will soon become your best friend when it comes to getting
your exposure right.
I have already discussed levels
and histograms in another tutorial so I won't try and re-invent
the wheel by explaining the theory here again. However, in a nutshell,
the image is made up of pixels ranging from the darkest tones
(to the left of the histogram) through the midtones (in the middle)
to the highlights (on the right side). The distribution of the
pixels (the shape of the peaks) is entirely dependant on the tonal
values of each scene but what you are trying to avoid with your
exposure is taking the pixels off the graph at either end of the
scale as you will have "clipped" those values and you
will have lost them for good. If you set your camera to shoot
RAW images you will have far more chance of recovering an image
with blown highlights than if you shoot Jpeg.
If your test image is under exposed you will need
to dial in some positive exposure compensation and if your highlights
are clipped (over exposed) as they are in the image on the right
below you need to dial in some negative exposure compensation.
Correct exposure with feather detail
Over exposed image with clipped highlights
To avoid digital noise (grain) creeping into your
images, it is best to apply sufficient exposure compensation to
push the histogram as far to the right of the graph without clipping
the peaks. This technique is termed "exposing to the right"
and I explain it more fully here.
You have a choice of camera metering modes to use when photographing
birds and all are equally valid. There are partial, centre weighted,
evaluative (matrix on Nikon) and spot metering to choose from.
Your camera handbook will explain all the modes in detail and
when to use each type. I don't know why, but I always wanted a
camera with spot metering - I think it was because it sounded
more professional, but now I have got it I can't recall the last
time I actually used it !
Despite all the metering mode choices, I would advise that you
try them but adopt just one of the modes and stick to it and learn
its strengths and weaknesses. The metering in all of the modes
relies on light reflected from the subject rather than the incident
light actually falling on it. Therefore they are all fooled under
certain subject or background lighting conditions such as when
a large area of a tone which is significantly darker or lighter
than a midtone is present - think of black crows or white swans
as subjects against white snow or very dark trees as backgrounds.
These are the extremes and the kind of occasions when you will
have to take control and override your camera.You can arrange
some still life setups using black and white cloths and subjects
of various tones and see how your camera copes under each circumstance
Different photographers have personal preferences but I
use evaluative metering most of the time as I find it the
most intelligent and it is often the simplest to use in the heat
of the moment. Exposure measurement in this mode is based on complex
algorithms evaluating the entire scene but is also linked and
biased towards the focusing point in use. It tends to get the
exposure right most of the time in bright conditions, but you
have to understand what it will do in shady situations and adjust
accordingly. I will come back to this later in the section on
Aperture or shutter priority ?
Like many wildlife shooters, I shoot almost
exclusively in aperture priority AV mode. That means I
choose the aperture and the camera automatically sets the shutterspeed
to compensate. I never use programme modes as the camera is taking
control of the image away from me and I might as well have bought
a point-and-shoot snapshot camera rather than an SLR which is
intended to produce art.
I don't tend to use shutter priority TV mode either, not because
shutterspeed is unimportant - of course it is, but I know that
if I choose to set my lens to its widest aperture I will get the
fastest shutterspeed available to me anyway before resorting to
changing ISO. Unless I am purposely trying to create motion blur
in an image, I look upon shutterspeed as a necessary evil - something
that you have to have to stop camera shake and subject motion
blur. My creative thoughts are usually aperture-related. e.g.
Do I want to blur the background more with a wider aperture, or
do I want to get more of the subject in focus by stopping the
lens down to a smaller aperture ? I have to still be vigilant
to the resultant shutterspeed that my choice of aperture will
give me, but I know that if the shutterspeed seems too low at
my chosen aperture I am going to have to increase the ISO setting.
Some Nikon and a few of the recent Canon cameras have an auto
ISO facility which sounds very useful - you set the aperture and
shutterspeed and the camera sets the lowest ISO accordingly to
achieve the correct exposure. If it can't balance the exposure
at the lowest ISO it will try again at the next ISO setting and
so on until it can.This has really only become of interest in
recent times as the high-ISO noise performance of the latest cameras
has become so good.
In shutter priority TV mode where you select the shutterspeed,
I find that if the light level drops - such as the sun going behind
a cloud, the camera quite frequently is forced to open up the
aperture to its fullest in an attempt to balance the exposure
and if that is still not wide enough to let in enough light, then
it has nowhere else to go and under exposure results. I really
don't want this happening when concentrating on photographing
birds in flight (BIF) for example.
I have recently read about a solution to the problem when shooting
in TV mode on the Canon 1D mk III which could be worth trying
for BIF. If the cameras is set to CFn I.8.2 (Safety shift ISO
enable) and you input any ISO setting other than the slowest one,
then the camera will open up the aperture to balance the shutterspeed
as usual, but this time, if it runs out of aperture it will select
a lower ISO instead of underexposing the shot. This is pretty
It is similarly theoretically possible to get an overexposed image
when a very wide aperture is set in Av mode if the subject is
so bright that the camera can't apply a fast enough shutterspeed
to balance the exposure. However, with cameras now shooting at
up to 1/8000 sec I have never actually come across this problem
in the real world.
Manual exposure for birds in flight
I like to use manual exposure (where you set both the aperture
and shutterspeed yourself) for situations such as birds in flight
(BIF) when the light is fairly constant but the brightness of
the background is changing as the bird flies across it. When I
was photographing red kites at a feeding station in Wales I found
that I was repeatedly getting incorrect exposure as the birds
swooped around against the wildly differing background - sky,dark
conifers and grass.
As the light was fairly constant and there is only one correct
exposure for the bird itself , I knew that if I dialled the correct
exposure into the camera manually it would be fixed at that and
I could then shoot away regardless of the background and forget
about the exposure unless the sun went behind a cloud for example.
But how do we know what exposure setting to manually put into
the camera ? The most accurate way would be to carry an incident
light meter and take a reading in the same light as your subject.
However, assuming you don't have such a thing in your camera bag,
what you need to do is look for a midtone area in your scene,
take a meter reading from it and set this into your camera. This
does depend on accurately judging midtones by eye but you get
better with practice. Sunlit grass is approximately a mid-tone,
as is a brick wall, a deep blue sky and a grey rock. At the first
opportunity check the histogram and apply exposure compensation
Exposure compensation required for evaluative
metering using a Canon camera
I have to thank the American bird photographer Art Morris for
my knowledge on exposure compensation when working in evaluative
metering. The table that follows is a summary of information I
gleaned from his bulletin
190 published in December 2005 with some tiny tweaks of my
own. I have used this ever since and I find it to be pretty much
spot-on. Remember this won't work for other exposure modes. I
have not tried this method with a Nikon set to Matrix metering
so I have no idea if it would work.
You should be working in Av mode and will need to adjust the exposure
using the big exposure compensation dial on the back of the camera.
The situations described in the chart are when the entire scene
in the viewfinder averages out to the tones described. To get
a feel of the average tones you can defocus the lens and look
at the overall tone of the scene much easier. You will have to
use your own judgment as to what a midtone looks like. An 18%
grey card is a mid tone and can be purchased cheaply from a photographic
supplier. The following block is approximately 18% grey :
|Darker than midtone
|Lighter than midtone
|Much lighter than midtone
|Bright highlights against midtone
0 or +1/3
|Bright highlights against darker than midtone
To simplify the chart even further, you can see that the
camera gets the exposure pretty well right all the time in sunny
conditions when used in evaluative metering mode. You just
have to watch blowing bright highlights a little when shooting a
scene with a dark background. If you are shooting in RAW there is
sufficient latitude to correct all of these slight exposure errors
in the RAW converter. So in sunny conditions you can virtually trust
the meter - this is why I like evaluative metering.
dull or cloudy conditions evaluative metering needs a helping hand
when the scene is lighter than a mid tone.
Basically, the lighter the scene is, the more light you need to
add. In fresh snow, your camera's meter will try to turn it into
a nasty midtone grey, so remember to overexpose the camera's reading
with the exposure compensation dial. The amount you over-expose
will depend on how much snow there is in your image compared to
subject. It may help to remember this with the expression "Add
light to white".
Willow tit in snow - 1/400
sec f5.6 +11/3 exposure compensation on a dull day
If a subject suddenly appeared unexpectedly in front of me against
snow on a dull day I would quickly dial in + 11/3 of over-exposure
in the evaluative (matrix) metering mode. The correct exposure
should be pretty close to this and as I shoot RAW, I can fine-tune
the exposure in the RAW converter and still get good results.With
a little more time, I would take a test image and then look at
the camera's histogram. Don't give up in low light levels or if
it starts to snow. You can get some very atmospheric shots in
Don't forget that a lot of bright highlights on water or very
pale sand can reflect nearly as much light as snow and you will
need to expose in a similar fashion.
- Shoot in AV mode, shoot in RAW, and use evaluative metering
- Trust the meter in sunny conditions but watch out for
blown highlights with subjects against dark backgrounds
- Add positive exposure compensation in dull conditions
if the scene averages to be brighter than a midtone.
- Take a test shot if time permits
- Check the histogram and make any adjustments
- Consider switching to manual exposure with birds in
flight and take your exposure from a midtone in the same
light as your subject. Check the histogram again and make