Tag Archives: wildlife photography tips

Back-Button focus – Wildlife Photography Tips #3

This article was also published in The Blue Bill, the Quarterly Journal of the Kingston Field Naturalists, Volume 67, No 1, March 2020.

If I had to pick a single technique that made a dramatic improvement to my capability as a wildlife photographer, I would choose Back-button Focus. It’s a technique used by professional wildlife and sports photographers, and can help you take your photography to a higher level.

It starts with the recognition that crisp focus is perhaps the single most important quality of a good photograph.

Autofocus

Because focus is so central to photography, camera manufacturers have developed ways to make it easier to get an in-focus image. Any camera produced in the last 20 years has the ability to focus automatically – indeed autofocus is the default option, and may have to be turned off if you wish to focus manually.

Autofocus is engaged when you press down on the shutter release. This happens so quickly some beginning photographers don’t even realize it is happening, but with practise most people learn that if they depress the shutter release halfway they can focus the camera without taking a picture.

Back-button focus

For most types of photography having the autofocus engage when you press the shutter release makes life easier – a single action both focuses the image and releases the shutter. Wildlife photography, though, has its own requirements and many wildlife photographers find that the simple shutter release/autofocus approach actually creates problems.

Instead they use back-button focus, where the autofocus function is disconnected from the shutter release and assigned to a different button.

I am not going to explain how to do this. Each camera system has its own way of assigning buttons, and you will need to consult your manual to learn how to make the change on your camera. Instead, I am going to explain why you might want to make this change.

Targets obscured by foliage

If you have spent any time trying to photograph birds in the wild I am sure you will have had this experience. You are trying to capture an image of a bird roosting in a tree within a tangle of branches, twigs and leaves. You can see the bird clearly, but frustration creeps in because each time you take a shot the camera focuses on a different one of the surrounding twigs and only occasionally on the bird.

For all the capabilities of modern autofocus systems, remember that they are not actually intelligent – they try to guess what you want to focus on but they are frequently wrong.

Back-button focus in wildlife photography
My eye sees the bird, but the camera decides that I want to focus on a vine.

Using back-button focus can solve this problem. You centre your camera on the bird and engage the focus. You may have to do this a number of times until the focus point is actually on the bird. In cases where there is a lot of background clutter you may even have to use manual focus. But the key point is this: once you are focused on the right point you can shoot as many images as you want without the camera trying to refocus each time. As long as you stay at approximately the same distance from the bird it will remain in focus. The camera will not be able to “help” by randomly changing the focus point.

Back-button focus in wildlife photography
Now that’s better. Sooty-capped Hermit, nr Monterrey, Casanare, Colombia, 5 Feb 2020

And even if you have to move slightly to get a better angle, if you engage autofocus again it will most likely zero in on the bird because it will be the closest object to the focus point.

I think you will find that once you try this technique you will be reluctant to go back to shutter release focus. Time that you might have wasted in focusing and refocusing can be spent on adjusting ISO and shutter speed and choosing the right moment to shoot.

Focus and reframe

Wildlife photographers often find that they want the focus point of an image to be off-centre. There are two main situations where this occurs:

Large or close-in target

Say you have a chance to see a Moose at fairly close range. You want to capture the whole beast in an image, without cutting off its tail or legs. But you also want your focus point to be on the eye, as tends to create the most compelling image. And not surprisingly, the Moose’s eye is at one side of the image.

Composition

You have a bird in your sights but you want to frame the image so that the bird is off-centre. You might want to better show its within its habitat, or to give it some open space in front of it, or just because people are more attracted to images where the main points of interest are off-centre.[1]

In these situations back-button focus is your friend. It allows you to focus on the desired point, and then without changing focus reframe the image by moving the camera until you get the result you want.

Back-button focus in wildlife photography
Purple Finch surveys his domain. Renfrew County, Ontario, Canada, 19 Jun 2019

Note that landscape and portrait photographers deal with this need by manually adjusting the camera’s focus point. In principle this would also work for wildlife photographers, but in my experience the focus and reframe method is much more intuitive and much faster to use. For subjects that tend to move suddenly and unpredictably I think it provides better results. Moreover it allows you to set your camera adjusted to centre point focus, which is the most accurate autofocus mode.

Continuous autofocus

For moving targets, such as a bird in flight, holding down the back button allows you to keep it continuously in focus while you wait the right moment to shoot – such as when it banks to show its upper wings. You can also hold focus on a stationary target, and you will be in focus when it pounces, takes off, or otherwise moves suddenly. Without holding focus the camera will need to refocus at the critical moment, with unpredictable results.

Back-button focus in wildlife photography
Battle is joined. Greater Prairie Chicken, Nebraska, USA, 2 Apr 2017

In principle you could also accomplish this by holding the shutter release halfway down, but in the real world of wildlife photography, where you will often be wearing gloves and your hands may be stiff from the cold, using a separate button removes the need for such fine motor control.

Of course you could just “spray and pray”, firing off twenty images at high speed and hoping one of them works. As long as you don’t mind everyone nearby assuming that you are clueless. 😊

Back-button focus – further advantages

While the above points are the key reasons for adopting back-button focus, there are a few minor advantages as well:

If you are using manual focus, you won’t then risk spoiling your own efforts when it’s time to press the shutter release.

Use of back-button focus reduces battery drain somewhat. Unlike shutter release focus it doesn’t automatically engage the lens’s image stabilization/vibration reduction motors.

The downsides?

Back-button focus is possible on most DSLRs and mirrorless cameras, but it may not be possible if you are using a bridge or superzoom camera. Check your manual to see if you can use this function.

And if you ask someone to take a picture using your camera, don’t expect great results. You can explain carefully the need to press the focus button and then press the shutter release, but I find that most people don’t “get” this and the images tend to be out of focus.

Other topics in this series

Wildlife Photography Tips #1 – Exposure Compensation

Wildlife Photography Tips #2 – Shutter Speed


[1] See https://en.wikipedia.org/wiki/Rule_of_thirds

Shutter Speed – Wildlife Photography Tips #2

Originally published in The Blue Bill, the journal of the Kingston Field Naturalists, Volume 66, No. 4, December 2019

Freezing the Action – Shutter Speed and Shutter Priority Mode

One of the major challenges of wildlife photography (and sports photography for that matter) is the need to choose a sufficiently fast shutter speed. Like all photographers we need to balance available light, depth of field, metering modes and focus points. But unlike, say, landscape or portrait photographers our subject matter tends to move quickly in unpredictable ways.

If our camera’s shutter speed is fast enough we will be able to “freeze” the action of fast-moving subjects and get a crisp image. So in principle the solution is to always use a fast shutter speed. And there are some circumstances where this approach will work. But much more often we will be engaged in a balancing act, adjusting variables such as shutter speed, aperture, and film speed (ISO) to get a correct exposure.

The Basics of Exposure

In very simple terms the image your camera produces is governed by the amount of light that falls on the sensor. A correctly exposed wildlife image will show the creature or plant in natural light with no areas that are too dark (underexposed) or too bright (overexposed), and will be crisp with no motion-induced blurring. Photo 1 shows an American Pipit, and to my eye the exposure is good – all detail is visible and the bird’s foot is frozen in mid-stride.

Photo 1 – American Pipit

Exposure is controlled by three settings: aperture (the amount of light that the lens allows to reach the sensor); shutter speed (the length of time that the sensor is exposed to the light); and film speed or ISO (the sensitivity of the sensor).[1]

Each of these variables has implications that the photographer needs to understand:

Shutter speed

As noted above, the primary way to get a crisp exposure of a moving animal (or a plant blowing in the wind) is to use a fast shutter speed. The downside of fast shutter speeds is that less light reaches your camera’s sensor. Shutter speed is expressed in fractions of a second. Each step up in shutter speed (e.g. from 1/250 to 1/500) halves the amount of light available. So except in very bright, sunny conditions faster shutter speeds can lead to underexposed images. To an extent you may be able to fix underexposure in post-processing, but artificially adjusting the exposure by more than a small amount adversely affects the quality of the image.

For stationary subjects you can use a slower than normal shutter speed and hope for the best, but typically the creature will move just as you snap the shutter. Photo 2 is a Coatimundi seen just after dawn. I had to use a slow shutter speed and a high film speed to get the shot. If you look closely you will see that the face is slightly blurry as it moves its head to the side.

Shutter speed 1/80
Photo 2 – Coatimundi

So if shutter speed isn’t the whole solution, what else can you do to increase your chances of getting a crisp image?

Aperture

Wide apertures allow more light in, so in the low-light conditions we are often dealing with a wide aperture seems like a good choice. The more light that passes through the lens, the faster your shutter speed can be. But as you might guess there are no easy solutions here. First, telephoto lenses capable of wide apertures are ruinously expensive. For example the Nikon NIKKOR 300MM ƒ2.8G ED lens, a favourite of professional wildlife photographers, will set you back a cool $6899.99 plus HST. So most of us will be using lenses with narrower apertures, and thus will have less light to play with.

Moreover, the wider the aperture, the shallower the depth of field. For the wildlife photographer, this creates a problem: the image may be correctly exposed but parts of the creature are not in focus. Photo 3, a Pearl Crescent, is correctly exposed. But even at ƒ7.1, a middle of the range aperture, the depth of field is shallow enough that the wing closest to the viewer is not in focus. The tails of birds can also fall prey to depth of field issues. In photo 4 the tail of the Canada Jay is a bit soft-edged, as it was beyond the optimal depth of field.

Film Speed (ISO)

Before the advent of digital cameras, photographers adjusted for low-light or fast-moving subjects by using faster film. So instead of ISO 64 or 100 film they might switch in a roll of ISO 200. This involved a big trade-off in image quality, as faster films producing grainer images. ISO 400 was about the maximum usable speed.

Now we have digital cameras capable of ISO equivalents of up to 51,000 so is the problem solved? Yes and no. Good quality digital cameras can produce very good images at higher ISO ratings, but only to a point. Just as fast film was prone to graininess, digital camera sensors can generate “noise” at higher speeds.

If you are interested in learning more about digital noise I recommend this post on the Photography Life site: https://photographylife.com/what-is-noise-in-photography

With my camera I can get excellent images at ISO 800, and very good ones up to ISO 1000. Speeds faster than that can work reasonably well depending on what you want the image for. Photo 2, for example, was shot at ISO 2000. The image is reasonably crisp and good enough for a record shot, but if you look above and to the right of the creature’s haunches you will see that the image becomes fuzzy (“noisy”) with some random colour blobs.

So what does it all mean? Simply that there is no single recipe for achieving crisp, properly exposed images of wildlife. While we are in the field we have to make continuous judgments about shutter speed, aperture and film speed to enable us to get the images we want.

Shutter Priority Mode

If you spend too much time thinking about these variables you may end up missing some of the action you went out to photograph. So most wildlife photographers use their camera’s mode system to automate part of this work.

All DSLRs and most bridge cameras have four basic operating modes: Manual, Shutter Priority, Aperture Priority and Program. I want to explain Shutter Priority mode here because I think it is the most useful option for wildlife photographers.

Your camera will have an easily accessible way of selecting this mode – most often by a rotating dial on the upper right side (Photo 5). For most DSLRs rotating the dial to S puts you in shutter priority mode. Eccentrically, Canon and Pentax call it “Tv” for time value, but the effect is the same.

Photo 5 – Nikon D5300

When you are operating in this mode, you can select the film speed and shutter speed you desire and the camera will automatically adjust the aperture within its limits to ensure a correct exposure. If there is not enough light to get a correct exposure at maximum aperture the camera will warn you somehow, often by inactivating the shutter release. Check your manual to see how your own camera works and what adjustments you can make.

You can actually go a step further and automate your choice of film speed as well. Somewhere in the menu system of your camera there will be an option to select “auto ISO”. This is a tempting option for wildlife photography, as it minimizes the chance of a missed shot. However beware of the fact that cameras left to their own devices tend to bump up the film speed to fairly high levels, so if you use this function check your manual to see if you can set an upper limit on auto ISO.

Recommended Shutter Speeds

So the final piece of the shutter speed puzzle is: how fast is fast enough?

In principle, unless forced to by low light I would recommend a minimum shutter speed of 1/500 for wildlife. Birds and mammals, even if they appear stationary, are often flicking their ears or looking around, so it’s best to err on the safe side. I did a quick check of the wildlife photos I am most proud of and almost all were shot at 1/500 or 1/640. There are exceptions, such as the Chestnut-naped Antpitta at photo 6 (1/00 at ƒ5.6) but I was fortunate that the bird held still for a moment.

Shutter speed 1/100
Photo 6 – Cjestnut-naped Antpitta

For frogs, turtles, and perched butterflies and odonates you can often get by with a slower speed, as they can sit still for lengthy periods. But the Snapping Turtle at photo 7 was being aggressive so I needed 1/500 to freeze her.

Shutter speed 1/500
Photo 7 – Snapping Turtle

Special Cases

Birds in Flight

There is a simple rule of thumb here: the fastest shutter speed you can manage is the one to choose. But you can cheat to some extent based on the type of bird and its activity. The Trumpeter Swan has fairly slow wingbeats, so in photo 8 even 1/250 was enough to get a crisp image. The gliding Red-tailed Hawk in photo 9 was shot in bright daylight so I was able to go to 1/3200 and ensure that the image was crisp.

The Greater Prairie Chickens at a lek in photo 10 were tricky. We were shooting at dawn so there was very little light available, and the birds were actively jousting. I found through trial and error that a shutter speed of 1/2000 was enough to freeze the action. To make that work I had to bump the ISO up to 8000. The resulting image is reasonably good.

By the way, don’t even think about trying to photograph butterflies in flight. That way lies madness.

Hummingbirds

Hummingbird wingbeats are so fast that it is difficult to get a crisp image even in optimal light. Shutter speeds of at least 1/3200 will be needed. And because their wings move in strange ways to allow them to hover, even if you do get a crisp image it will often look rather odd. So unless you can find a perched bird, I find the best approach is to intentionally allow a bit of blur in the wings, which gives the impression of movement. The Western Emerald in photo 11 was shot at 1/320 while hovering. This is about right for the wings, but as you can see the tail is a bit blurred, so a slightly faster speed would have resulted in a better image.

Shutter speed 1/320
Photo 11 – Western Emerald

So that’s the bluffers’ guide to shutter speed. if you have mastered the basic operation of your camera and want to dip your toe into more advanced options why not try experimenting with shutter priority?

Previous posts in this series

[1] Almost all cameras now are digital and do not use film, but the term film speed is still widely used to describe this function.