Nikkor 16-85mm f/3.5-5.6 | 35mm equivalent | f-stop range |
---|---|---|
16mm | 24mm | f3.5-f22 |
24mm | 36mm | f/4.0-f/25 |
35mm | 52.5mm | f/4.5-f/29 |
50mm | 75mm | f/5.0-f/32 |
70mm | 105mm | f/5.6-f/36 |
85mm | 127mm | f5.6-f/36 |
Like the Canon SD780 IS and Nikon P5100, the maximum and minimum apertures are variable depending on the focal length of the lens. At 85mm, it goes all the way up to f/36! This is not as great an advantage as it seems though, since diffraction begins to soften images above f/11. To get the best combination of depth of field vs. sharpness, work between f/8 and f/11.
Remember the old photojournalists’ saying, “f/8 and don’t be late”.
On the other hand, f/5.6 is a memorable number, as it’s available across the board, and gives good all-around results regardless of which focal length you use. Happily, as long as you don’t manually change the aperture, the D90 returns to the maximum aperture for any given focal length automatically as you zoom back out. But if you change it, it sticks, which is one reason I like to work with a single focal length whenever I can.
Prime lenses such as the Nikkor 20mm f/2.8D, 35mm f/1.8G, 50mm f/1.4G, and 85mm f/1.4G all have distinct advantages in both size and speed over the Nikkor 16-85mm, but VR narrows that gap somewhat. In theory, at 35mm, VR makes the 16-85mm behave similar to f/1.8, (except for the ability to freeze action), but it can't compete with the compactness of the 35mm f/1.8.
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