why scanning with real scanner is better than scanning with a digital camera:

• A real film scanner has a lens that has zero geometric distortion, a flat field and generally is optimised for equal sharpness and brightness across the usable field — this isn’t generally the case with even good general photographic lenses

• A real film scanner has a film transportation system that blocks out all other light — often the same is not practical for many home DSLR scans

• A real film scanner precisely orients the film to be perfectly perpendicular to the lens on all axes. This is very difficult to achieve with home-built DSLR scan setups unless proper reproduction stands and the like are used and carefully aligned

• A real film scanner has a very uniform light source which it calibrates at startup time (the calibration ensures that the X direction irregularities that remain are known and compensated for in the scan — the Y direction irregularities are controlled by the fact that the same light source is used as each row is scanned so as long as the output is constant there should be no Y direction irregularities)

• A real film scanner uses a line sensor array and exposes the individual colour channels sequentially for each position. This gives full colour resolution. There is no “Bayer matrix” and no de-mosaicing process necessary

• Many real film scanners are able to automatically remove defects and dust at scan time by doing an additional capture of the infrared light channel (which most film is transparent to apart from black and white and famously Kodachrome).

• A real film scanner does separate exposures for the Red, Green, Blue (and often Infrared) wavelengths. These exposures need not be the same. A DSLR must necessarily use the same exposure for all wavelengths because one shutter controls illumination for the entire RGB sensor

https://smashandgrabphoto.wordpress.com/2017/10/27/why-not-dslr-scan/#more-568 #photography #scanning #scan #dslr #bayer_matrix #colour

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