摄影资料馆 › 胶卷图鉴
胶片的分辨率，为什么没有一个像素数
胶片厂商给的「分辨力」，是在规定的对比度下还能分开的最细线条，单位是每毫米多少线。
同一款胶片，测试图的对比度越高，这个数就越大。富士的资料同时给出 1.6:1 和 1000:1 两种对比度下的数值。
MTF 说的是另一件事：细节越来越密时，画面里的反差还剩多少。MTF50 是反差降到一半时的细节密度，通常比分辨力的极限低得多。厂商只以曲线发表 MTF，本站不从曲线上读数。
一次扫描最后能留下多少细节，还取决于镜头、对焦、颗粒、冲洗和扫描仪。
所以下表的百万像素只是上限。它按 36×24 毫米的画面、每对线条用两个像素、整套系统都理想来计算，适合比较不同胶片，不代表任何一张照片的真实细节。
| 胶卷 | 测试对比度 | 分辨力（线/毫米） | 百万像素上限 |
|---|
| Fuji C200 | 1.6:1 | 50 | 8.6 |
| Fuji C200 | 1000:1 | 125 | 54.0 |
| Fujifilm Superia 400 | 1.6:1 | 50 | 8.6 |
| Fujifilm Superia 400 | 1000:1 | 125 | 54.0 |
| Fujifilm Pro 400H | 1.6:1 | 50 | 8.6 |
| Fujifilm Pro 400H | 1000:1 | 125 | 54.0 |
| Fuji Provia 100F | 1.6:1 | 60 | 12.4 |
| Fuji Provia 100F | 1000:1 | 140 | 67.7 |
| Fujifilm Velvia 50 | 1.6:1 | 80 | 22.1 |
| Fujifilm Velvia 50 | 1000:1 | 160 | 88.5 |
| Fuji Velvia 100 | 1.6:1 | 80 | 22.1 |
| Fuji Velvia 100 | 1000:1 | 160 | 88.5 |
假设：35 mm 画幅 36×24 毫米；把厂商资料里的「每毫米线数」当作每毫米线对数；每个线对两个像素；镜头、对焦和扫描都理想。
数据来源：富士胶片各型号技术资料，引用其中文字和表格里的数值。
Photography Library › Film Stock Encyclopedia
Why film has no single megapixel number
A film maker's resolving power is the finest line pattern that can still be told apart at a stated test contrast, in lines per millimetre.
The same film scores higher on a higher-contrast target. Fujifilm's data sheets give figures at both 1.6:1 and 1000:1.
MTF describes something else: how much contrast survives as detail gets finer. MTF50, where contrast falls to half, sits well below the resolving limit. Makers publish MTF only as curves, and this site does not read values off curves.
How much detail a scan finally keeps also depends on the lens, focus, grain, processing and scanner.
The megapixel figures below are therefore upper bounds. They assume a 36×24 mm frame, two pixels per line pair and an ideal system throughout. They help compare films; they do not describe the detail in any photograph.
| Film | Test contrast | Resolving power (lines/mm) | Upper-bound megapixels |
|---|
| Fuji C200 | 1.6:1 | 50 | 8.6 |
| Fuji C200 | 1000:1 | 125 | 54.0 |
| Fujifilm Superia 400 | 1.6:1 | 50 | 8.6 |
| Fujifilm Superia 400 | 1000:1 | 125 | 54.0 |
| Fujifilm Pro 400H | 1.6:1 | 50 | 8.6 |
| Fujifilm Pro 400H | 1000:1 | 125 | 54.0 |
| Fuji Provia 100F | 1.6:1 | 60 | 12.4 |
| Fuji Provia 100F | 1000:1 | 140 | 67.7 |
| Fujifilm Velvia 50 | 1.6:1 | 80 | 22.1 |
| Fujifilm Velvia 50 | 1000:1 | 160 | 88.5 |
| Fuji Velvia 100 | 1.6:1 | 80 | 22.1 |
| Fuji Velvia 100 | 1000:1 | 160 | 88.5 |
Assumptions: a 36×24 mm frame; the maker's lines per millimetre read as line pairs per millimetre; two pixels per line pair; ideal lens, focus and scanning.
Source: Fujifilm data sheets for each film; values are taken from their text and tables.
