一个变焦镜头在一个焦点段的锐度和十月21日拍的月亮（修改版）
先得谢谢位酷哥，位酷哥让我找我的镜头的锐度，没他的帮助是不可能有这篇文章的。
什么是锐度：
"Sharpness of a lens" refers to the ability of a camera lens to capture fine details in an image, meaning how crisp and clear the subject appears, with a sharp lens producing distinct edges and textures, while a less sharp lens might result in blurry or soft details; it's essentially a measure of the lens' resolution and is often judged by how well it can render fine lines and patterns across the entire image frame, from the center to the corners.
单焦镜头的锐度只有一个:
For most lenses, sharpness in P-Mpix is typically between 50% and 100% of the sensor pixel count, and differences smaller than 1 P-MPix are usually not noticeable. The best resolutions are usually achieved by prime lenses at apertures between f/2.8 and f/8.
变焦镜头的锐度在不同的焦段是不同的：
Google的AI回答：
In a zoom lens, sharpness typically varies across the zoom range, with the best sharpness usually found in the middle of the zoom range, while the extreme wide and telephoto ends tend to be slightly softer; this means a zoom lens is often not as sharp at its maximum zoom as it is at a middle focal length, and is generally considered less sharp than a prime lens with a fixed focal length due to its complex internal mechanics.
For a zoom lens, the aperture at which you find the best sharpness at a specific zoom range is usually not fixed across the entire zoom range; most zoom lenses have a variable aperture, meaning the maximum aperture changes as you zoom in or out, so you may need to adjust your aperture depending on the focal length you're using.
位酷哥建议我用ISO12233去查锐度。
我刚刚从aliexpress order了一个，还没接到：
位酷哥建议在没有锐度表的情况下可以用不同的光圈拍照片试一下。我用50-500mm变焦镜头在500 mm的焦段从f/6.3到f/32拍了12张照片，找到f/9和f/11是最清晰的光圈 .
注意这只是在500mm焦段的最佳锐度，其它的焦段，例如50mm,我还没有试。到用时再试，最简单的事情是来了锐度表再试。
以下是硬件和软件：
Camera: Nikon D300s
镜头：Sigma 50-500 mm
三脚架：Manfrotto 501HDV
Size: 3216x2136 pixels
ISO：200
Exposure: +5 EV
Mode: M
Focal length： 500 mm
Sharpen: by Corel AfterShot pro 3.0
以下是 12张从原始照片割下来月亮的照片.
10/21/2024 9:45:31 pm 开始第一张, 9:56:21 pm 结束最后一张。
1. 相片：#688
Shutter Speed: 1/100 s
Aperture: f/6.3
2. 相片：#690
Shutter Speed: 1/100 s
Aperture: f/8
3. 相片：#691
Shutter Speed: 1/100 s
Aperture: f/9
Exposure +0.81 EV
4. 相片：#692
Shutter Speed: 1/100 s
Aperture: f/10
Exposure +0.76 EV
5. 相片：#697
Shutter Speed: 1/50 s
Aperture: f/11
6. 相片：#703
Shutter Speed: 1/30 s
Aperture: f/13
7. 相片：#722
Shutter Speed: 1/20 s
Aperture: f/18
8. 相片：#730
Shutter Speed: 1/8 s
Aperture: f/20
9. 相片：#739
Shutter Speed: 1/8 s
Aperture: f/22
10. 相片：#749
Shutter Speed: 1/8 s
Aperture: f/25
11. 相片：#758
Shutter Speed: 1/3 s
Aperture: f/29
12. 相片：#767
Shutter Speed: 1/5 s
Aperture: f/32
下面是从以上照片割下来的局部照片：
1. #688, f/6.3, 1/100 s
2. #690, f/8, 1/100 s
3. #691, f/9, 1/100 s, +0.81 EV
4. #692, f/10, 1/100 s, +0.76 EV
5. #697, f/11, 1/50 s
6. #703, f/13, 1/30 s
7. #722, f/18, 1/20 s
8. #730, f/20, 1/8 s
9. #739, f/22, 1/8 s
10. #749, f/25, 1/8 s
11. #758, f/29, 1/3 s
12. #767, f/32, 1/5 s
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