一個變焦鏡頭在一個焦點段的銳度和十月21日拍的月亮（修改版）
先得謝謝位酷哥，位酷哥讓我找我的鏡頭的銳度，沒他的幫助是不可能有這篇文章的。
什麽是銳度：
"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.
單焦鏡頭的銳度隻有一個:
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.
變焦鏡頭的銳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.
位酷哥建議我用ISO12233去查銳度。
我剛剛從aliexpress order了一個，還沒接到：
位酷哥建議在沒有銳度表的情況下可以用不同的光圈拍照片試一下。我用50-500mm變焦鏡頭在500 mm的焦段從f/6.3到f/32拍了12張照片，找到f/9和f/11是最清晰的光圈 .
注意這隻是在500mm焦段的最佳銳度，其它的焦段，例如50mm,我還沒有試。到用時再試，最簡單的事情是來了銳度表再試。
以下是硬件和軟件：
Camera: Nikon D300s
鏡頭：Sigma 50-500 mm
三腳架：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張從原始照片割下來月亮的照片.
10/21/2024 9:45:31 pm 開始第一張, 9:56:21 pm 結束最後一張。
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
下麵是從以上照片割下來的局部照片：
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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