Lou Coetzer illustrates how two very different scenes – one close, one far, one dynamic, one static – requiring vastly different depths of field, can be captured with the same lens combination and identical f-stop.
I was on my way out of Namibia’s Etosha National Park when I saw these giraffe slowly walking towards the pan. It was a breathtaking scene, one that I would have to work hard to capture.
As I had already packed my window bracket away, I would have to steady my heavy 600mm lens (and its 1.4x teleconverter) by hand. I also estimated that the two nearest giraffes, seen on the left of this image, could be 30m or more closer too me than the rest. Thankfully, the further away the subject is the easier it will be to render everything sharp that is required to be.
It was important to make sure that the camera’s focusing sensor was placed on one of closest giraffes, so I moved it manually, placing it on the second giraffe from the left. I then opened the lens to the maximum f-stop. Then, by using a high ISO and under exposing further against the strong back lighting, I allowed a fast enough shutter speed to counter the vibration of an old photographer handholding a very heavy lens.
I spotted this polyandrous African jacana leading his two chicks into a thick reed bed, which was drifting on a secluded part of the Chobe River in northern Botswana. After waiting for what felt like eternity, I spotted the father come into view. Limping, he appeared to be feigning injury to lead us away from the chicks. However, when I looked through the lens I saw tiny feet hanging out from beneath his wings – he was carrying his young slowly away from us!
Before we knew it, the male turned and then rapidly ran parallel to the boat from one water lily to the other. With little time, soft early morning light and a long telephoto lens (600mm with 1.4x teleconverter), my work to capture this dynamic scene would certainly be demanding.
Requiring a high shutter speed, I pushed up the ISO as high as I was prepared to go to maintain a good image quality. I then chose the largest aperture available to blur the background as much as possible. I had to discipline myself to keep the focus sensor on the bird at all times. From my previous experience I also knew that the whites on the head and neck of adult African jacanas are easily over exposed, so despite the soft light I underexposed the image further.
When you have a very shallow depth of field, such as when a small subject is filling the frame of your long telephoto lens, you will have an easier time getting sharpness throughout the vital areas of the photograph if you can position yourself parallel to the subject’s movement.
Learn more about Lou Coetzer, his images and the photographic-workshop safaris he runs at www.coetzernaturephotography.com