Here’s a list:Īs already explained, stopping down the lens causes a loss of sharpness everywhere in the image due to diffraction. Stopping the lens down to the smaller apertures – f/16 to f/32 - creates many problems that are easily avoided by using more intermediate apertures such as f/8 or f/11. Although photographer opinions vary, I feel that f/32 and even f/22 is worthless on this lens and probably most other lenses as well. Although, in theory, the depth of field is greater at f/32, the overall image sharpness is far less than f/11 due to diffraction. I was horrified by how bad it is at f/32-even f/22 produced underwhelming results. When I tested the diffraction on my Canon 180mm macro lens for a new book-Close Up Photography in Nature. This bending is known as diffraction and causes a loss of sharpness everywhere in the image. Due to the wave nature of light, as the hole it passes through decreases in diameter, a larger percentage of the light touches the edge of the hole and bends. In simple terms, these f/stops refer to the tiny hole in the lens that is called the aperture. Due to the laws of physics, though, the greatest depth of field is always at the smallest aperture (largest f/stop number) which is usually f/22 or f/32. With a 200mm f/4 lens, for example, the sharpest apertures are around f/8 to f/11. The sharpest aperture on the lens is typically two to three stops down from the maximum aperture on the lens. All photographers have problems achieving sufficient depth of field and superb image sharpness imultaneously because it is a trade-off.
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