Originally Posted by
interneg
In two words: optical aberrations. It's perfectly possible to design a very cheap optical system with surprisingly good high contrast resolution and much worse performance elsewhere, loaded with spherical aberration that kills fine, more normal contrast details. That's what the Epson does, much like the lenses in disposable cameras. It's like the difference between a pre-aspherical 35mm Summilux at f1.4 & an Apo-Sironar (choose your flavour) at f22. One could be theoretically higher resolving (diffraction etc) but one will be clearly far, far more perceptibly 'sharp' owing to lack of spherical aberration. The sheer number of glass surfaces in the Epson between film & lens will also drastically increase the amount of halation present, over and above any potential performance of the lens/ optical system. The high price of high-end CCD scanners had and has a great deal to do with a flatbed optical system that's free to a great extent of halation & chromatic aberration, using highly corrected optical systems to do so.
No amount of fiddling in Photoshop will change that - unlike distortion or chromatic aberration correction. Do you now understand why an aberration free 2048ppi is vastly better than a grossly aberrated 2300ppi?
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