Pixels and clarity! ! Does it matter?

In addition, the relationship between imaging details, lens resolution and pixels per inch of photoreceptor is extended and explained.

The lens has resolution, for example, the resolution of a lens is 100lp/mm, and lp is a line pair (2 lines), that is, black line and white line. Then it can be understood as the imaging of the lens, and the details of 0.005mm or 5um can be identified.

The lens is mounted on a camera with very low pixels per inch, such as a full-frame camera with 3 million pixels (of course, this is only an analogy, and the example given is extreme). The resolution of a 3-megapixel photo is 2048* 1536, and the size of a full-frame camera is 36 * 24 mm It can be calculated that the pixel per inch is about 17um.

Then this lens with an imaging detail of 5um is projected onto the photoreceptor with only 17um pixels per inch, which will inevitably lead to the photoreceptor being unable to restore all the details that the lens can restore at 100% (only about 1/3 details can be restored). This condition is called that the photoreceptor cannot feed the lens.

So even machines like 5D2 and 645D can't feed this lens with about 6um pixels per inch. Conversely, if your lens resolution is only 50lp/mm, then this lens can't feed the camera.

Therefore, if all prints and printed matter are 300DPI, regardless of the enlargement size, then using a very high-end lens and a high-sensitivity sensor with pixels per inch can bring more details. Of course, as you said, the resolution is only related to the output format and does not conflict. It only further explains the relationship between lens resolution, photoreceptor format, photoreceptor pixel, output photo size and detail reduction.

The high pixel per inch photoreceptor has a low dynamic range (i.e., the tolerance of the film machine), and the aperture ratio of the lens of the photosensitive unit is also low. When taking photos of Gao Fancha, the details of bright and dark parts will be lost, and the high sensitivity will become worse.

Therefore, the digital back used in many commercial photography fields will not be particularly good in high sense and dynamic range. However, most of these machines are used for tent shooting. Generally, the light ratio is required to be controlled in the range of 1:3, and high sensitivity is not used at all (so CCD with better low sensitivity is generally used on the back of digital, instead of CMOS photoreceptor with better high sensitivity).

Therefore, in photography, it is required to achieve "three lows": low contrast, low saturation and low sensation. Three-low photos contain the richest details and have the biggest room for later adjustment. Among them, low contrast and low sensitivity are related to this problem.