When it comes to wildlife photography, the best results are achieved when your subject stands out. In order to do this you need a clean background that is a bit of a distance away from the subject and a small aperture i.e. f2.8.
Now this may sound easy, but it is not as if you can ask the lion to move slightly to the left to get the clutter out of the picture. So the only answer I have for you is to be patient and wait for the perfect opportunity. To get this photo I had to sit with the lions for about an hour as they were lying in some thick bush. Eventually this cub decided to come out and have a look at me waiting patiently in the Land Rover. I literally had about 2 minutes to get the image before he disappeared back into the bush - so make sure that while you are waiting, your camera settings are all ready for when the opportunity comes. If you have the chance take a few test images to make sure your exposure is right.
This photo was taken with a Nikon D600 and a Nikkor 200-400 f4. Because it was overcast I had to pump my ISO up to 1000 in order to accomplish a shutter speed of 1/640th of a second. That speed was necessary to compensate for the fact that I was extended to 400mm and I was hand holding the camera. This bettered my chances of getting a sharp image of the lion cub. I set my aperture to f5 to get enough depth of field to keep him sharp and in focus while still blurring the background to ensure that the cub stood out. The best type of background is one with uniform colour as it is less distracting to the person viewing the photograph.
Expose your balance
Richard de Gouveia