Wildlife Photography_ From Snapshots to Great Shots - Laurie Excell [6]
• Minimum focus distance. Just how close will your lens focus? The Nikon 600mm f4 VR has a minimum focus distance of 15.7 feet, whereas the Nikon 200–400mm f4 VR can focus as close as 6.6 feet. Although you may not have much choice over minimum focus distance and lens selection, it’s good to know up front just how close your new lens will focus. You can make up for lack of magnification if you can move in closer to your subject.
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Tip
Don’t treat your lens purchase lightly. A good lens is a lasting investment compared to a camera body that becomes obsolete every 18–24 months. Purchased wisely, the right lens will last you for years to come.
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Increasing Focal Length with Teleconverters
When even greater reach is needed to bring the subject to the desired size in the frame, teleconverters are available from manufacturers that match up with their high-end long lenses for increased magnification. It’s an inexpensive way to increase your focal length. But the cost is loss of light, beginning with a one-stop loss of light with a 1.4X, a one-and-a-half stop loss with a 1.7X, and two full stops of light lost with a 2X teleconverter. Your camera adjusts for the change of exposure automatically. Nikon and Canon’s teleconverters are designed to work with their longest and fastest lenses. Refer to your instruction manual to see which teleconverters are compatible with your camera/lens combination. Figure 1.8 shows Nikon’s teleconverters.
Figure 1.8 From left to right, Nikon’s TC-14E II, TC-17E II, and TC-20E III.
A small, shy subject needs all the magnification you can get so you can keep your distance and yet still get a sizeable image in the frame. The 600mm f4 with a 2X teleconverter becomes a 1200mm f8 super telephoto (Figure 1.9).
Figure 1.9 Manual focus was used due to the two-stop loss of light, giving a maximum aperture of f8.
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The Function of Teleconverters
Cameras need plenty of light to see to focus, just like you do. The max aperture that a camera can still see through well enough to focus at its peak performance is 5.6. If a lens’s max aperture becomes smaller than f5.6 with the addition of a teleconverter, focus will slow down noticeably or quit working entirely. So although Nikon and Canon teleconverters work on all their high-end long glass, you’ll sacrifice speed for increased magnification. For example, using a 600mm f4 lens with a 1.4X teleconverter becomes 840mm f5.6. Focus is still at its maximum capability. With a 1.7X, focus becomes 1020mm f6.7. (Note that at f6.7, focus begins to act sluggish.) With a 2X, the total focal length is 1200mm with a maximum aperture of f8, providing any autofocus at all in only the brightest light, and it is sluggish at best. Manual focus is preferred with a 2X attached to a long lens with a max aperture of f4.
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To Flash or Not to Flash
Although I don’t often use flash in the field, preferring natural light in most cases, there are times when adding a little fill light simply makes all the difference between a snapshot and a great shot. Flash will remove a color cast caused by the light conditions, bringing out the true colors of your subject, as well as add a catchlight to your subject’s eyes. One case in point was when I was trying to photograph a Great Horned Owl in an Australian pine at Fort De Soto in Florida. He was perched high among the branches with a bright sky behind him that backlit him and made him appear too dark. I could have added plus exposure compensation, but it would have brightened the background as well as the owl. So, I reached into my bag and pulled out my SB-900 with the Better Beamer flash extender (Figure 1.10). I didn’t want to have a “flashed” look to the image but rather wanted to pop just a little fill light onto the owl to bring