Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Ben Rubinstein on April 08, 2007, 12:22:38 pm
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For 4X5 the Imacon 848 at my pro lab will scan at 2040DPI. The Epson flatbed V750 scans at 6400DPI. Now I know what that Imacon produces, it gives absolutely amazing results resolution wise from the medium format work I've had scanned there. But 2040 is pretty low even with such a large neg giving a 34"
X27" image @ 300DPI. I know that comparing the Imacon to the Epson is like a p&s to a DSLR but there is still a huge difference in the numbers is there not?
Confused...
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Uprez the Imacon to the Epson's max optical rez and see if there's a difference between them. I'ld be curious to know.
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Looks like the optical rez of the Epson is 4800. But you also have to check the spec's based on film size since it use a lens and higher rez are usually applied over a smaller original like a 35mm. When give a spec like 1200x2400, disregard the 2nd value, its not true optical rez. Also, I suspect the lens in the Imacon (a Rodenstock) cost more than the entire Epson.
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The maximum uinterpolated resolution of a scanner is far less meaningful than True Optical Resolution and the quality of the scan in general based on the quality of the optics, ccd sensors etc. Having used both of these scanners extensively, scanning 4x5, the Imacon is much superior. But I rarely print larger than 16x20 so I have no point of comparison for an upresed Imacon scan vs, the 750 at its TOR.
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I have an Epson 4800 dpi (optical resolution) flatbed with impressive D-Max specs of 4.2. It's even capable of scanning 8x10 film.
However, having compared the results with my Nikon 8000ED dedicated MF film scanner with optical resolution of 4000 dpi, I find the Epson flatbed produces blocked shadows, implying the D-Max spec is highly exaggerated, and lower resolution, implying the lens is inferior.
The resolution difference might be analagous to using an 8x10 LF lens on a 6x7 MF camera as opposed to using a dedicated (and sharper) MF lens on that MF camera.
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Spec's for scanner dynamic range are usually BS. There's no universally accepted method of making such values up since the figures for this range are supposed to begin past the point the scanner creates real data and not noise. The manufacturers are free to decide what's noise and what's data. YMMV. In the very old days (1990's) it was amusing to see Linotype and Microtek provide scanner spec's for dynamic range. Same hardware! Linotype was always very conservative.
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So there is no doubt that I would be able to resolve more detail with the Imacon? It's for very large prints (50X40") and I would want as much detail pulled out of the neg as possible. The shadows issue is still important though, especially when working with B&W.
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The epson V750 offers a dual lens system with an anti reflective coating on the ccd. One lens (super res) does offer a true optical resolution of 6400 dpi (6400 x 9600 dpi) on film sizes up to 5.5 inches. The second lens (high res) offers optical resolution of 4800 dpi on film sizes over 5.5 inches to 8 x 10 inches.
The fluid mount unique to the V750 can minimize scratches on old film. The digital ice electronics also help minimize dust and scratches on non-monochrome film.
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Pom, Yes the Imacon will resolve more detail. I own the 750 and do wet mounting. I also have access to that Imacon where I teach photography. So I do these comparisons all the time. The Imacon will resolve more detail because it has superior optics and sensors. When I want to print larger than 11x14 I go to the Imacon (though in general the 750 is pretty competitve at normal viewing distance up to 16x20).