We recently made the upgrade from our trusty Nikon 300mm F/4 D to the Nikon 300mm F/4 PF – there was nothing wrong with our old versions and they worked perfectly well, but it was time for a change. Our motivation for upgrading was that the original 300mm was quite a bulky and weighty lens to lug around the place; the newer version is approximately half the length and weight of our original 300mm. Nikon has achieved this through the clever use of a Phase Fresnel lens that allows the lens to be constructed much shorter than typical lenses of the same focal length. We have found that this smaller, lighter lens is easier to carry on day long hikes, and much easier to use to track birds in flight as you are able to react to changes in direction much easier.
So how do we achieve crisp photos of birds whilst they are in flight? Well, not very well and we are still at the bottom of a steep learning curve; its much easier when they stay still. However, by making a singular and small change to our settings, we have made a dramatic difference to our success rate and as a result have started to produce more keepers. This simple setting change is Back Button Focus (BBF – I can hear my brother rolling his eyes as he has told me about this numerous times and I have never really got on with it). Back button focus is a method whereby you decouple focussing and metering from the main shutter button on the camera and assign the focus mode to a separate button on the camera (normally on the rear), that can be operated by your thumb. The advantage of this is that you are able to focus on your subject, using one button, and then use another button to take the photo. This is a small change, but rather than relying on a single button to do two functions, the camera can operate quicker as the two button functions are now separate. With both shutter and focus functions assigned to a single button, the camera will prioritise achieving accurate focus before firing the shot – and sometimes even refuse to take a photo if focus is not achieved. When shooting wildlife, this is far from ideal as it adds a fractional delay to the firing the shutter and you will miss more shots that you want.
Sounds simple in theory, but it takes a little while to get used to as you have to remember that you are now pressing two buttons to operate the camera. Years of muscle memory have to be reprogrammed quite quickly, and I have picked my camera up after periods of not using it wondering if my camera is not focussing! On a recent trip to the Catskill mountains, I experimented with both single-button and back button focus. An experiment that resulted in me nailing the focus more often than not when using back button focus. The picture above of a Hawk is a great example from this experiment as I took it using my old method. As the bird moved to launch itself from the branch, the camera did not release the shutter at the exact moment I wanted it too and as it was still prioritising focus, leading to a missed shot. In contrast, the photo of the Turkey Vulture at the start of this post was taken using the back button focus method, a method that resulted in a slew of 40+ photos, all in focus, of the bird as it drifted passed my viewpoint from a Fire Tower.
I would like to add that over the years I have learnt to get used to single button focus / shutter and managed to take a slew of good photographs with this method, such as the Osprey I photographed below.
Having given the back button focus a go during our stay in the Catskills it led to a little bit of an obsession with trying to take photographs of birds in flight! Whilst standing on a beach on Long Island there were a couple of dozen Terns teaching their fledglings to fish – leading to many opportunities for me photograph Terns hovering and diving into the water. This was an excellent chance to practice using the BBF and tracking birds. Using the new technique, and different AF-Area modes (I found group fair better as it presented a larger area in the view finder to track the bird with) I was able to record numerous Terns as they hovered and dove into the water! Proof that the new technique was worth learning and mastering further. Half the battle will be learning to predict what the birds are about to do, and the direction in which they are going to do it and hoping that my reactions are quick enough.
They are not!
If you want to know how we set up back button focus on our Nikon D750 camera, here is a good guide or here for other camera types.
Below is a selection of birds in flight, either taken with back button focus or our old method, including some failures!
