Sigma50-500毫米镜头在500毫米焦段f/14, f/13 and f/11是能拍出清晰照片的最好的光圈
一个单焦镜头通常只有一个最佳的光圈能拍出最清晰的照片，这个最佳光圈通常是在
The sharpest aperture for a prime lens depends on the lens itself and is best determined by testing it. However, the sharpest aperture is usually a few f-stops smaller than the lens's largest aperture. For example, if a lens's largest aperture is f/2.8, its sharpest aperture might be around f/4 or f/5.6.
chatGPT:
Many lenses have a "sweet spot" where they perform at their sharpest. For most lenses, this is typically around f/5.6 to f/8. At these apertures, diffraction (which softens the image) is minimized, and the lens is resolving details at its best.
相机：Nikon D300s
镜头： Sigma 50-500 mm 1:4-6.3 APO DG HSM D
ISO 800
+ 5EV
下面是重新拍的照片，结果和结论。
1. 原图，下图（#1402， f/11， 1/15 s, ISO 800）只是31张照片的一个例子， 注意图的中心的形状：
2. 下面是原片放大到100%的图， 查看 f/14, f/13 和 f/11，用黄背景写的字和图：
#1397, f/6.3, 1/50 s
#1398, f/7.1, 1/40 s
#1399, f/8, 1/30 s
#1400, f/9, 1/25 s
#1401, f/10, 1/20 s
#1402, f/11, 1/15 s
#1403, f/13, 1/13 s
#1420, f/13, 1/8 s
#1419, f/13, 1/10 s
#1418, f/13, 1/13 s
#1417, f/13, 1/15 s
#1416, f/13, 1/20 s
#1415, f/13, 1/25 s
#1414, f/13, 1/30 s
#1404, f/14, 1/10 s
#1405, f/16, 1/8 s
#1406, f/18, 1/6 s
#1407, f/20, 1/5 s
#1408, f/22, 1/4 s
#1409, f/25, 1/3 s
#1410, f/29, 1/2.5 s
#1411, f/32, 1/2 s
3. 下面是原图放大到100%, 然后割出带有中心的部分:
f/14, #1404, 1/10 s
f/13, #1414, 1/30 s
f/11, #1402, 1/15 s
4. 结论：
f/14， f/13和 f/11是Sigma 50-500 mm 镜头在500 mm焦段最好的光圈，用这三个光圈在500 mm焦段能拍出比用其它光圈拍出更清晰的照片。
