I have an old 3-in-1 printer/scanner/copier (Canon MF4100) LaserJet. I tried scanning some slabbed coins tonight and the results were *awful* (see attached). I put four slabs on the glass at once, but I don't think that affected anything. It defaulted to 300 dpi, but then I found a setting (I use IrfanView) to go to 600 dpi. But it's blurry. Is it just that I have a crappy scanner?
I think the scanner is having problems scanning through the plastic slab. Probably something to do with the light from the scanner reflecting a bit off the slab. I'm just spitballin' here...
My scanner has the same problem. I know others use a scanner for slabs. I will be interested to hear how to correct this.
Ditch the scanner for a point-and -shoot camera. You'll get much better results. I never was satisfied with my scanner results........none of them.
Many (most?) scanners will only produce a sharp image of something that's flat against the glass. The coin's surface is at least a millimeter or two away from the glass. You'd probably see the same thing if you put one coin directly on the glass and then placed another so it was partly overlapping the first. I see that frequently on eBay -- someone dumps a bunch of coins onto a scanner, and only the ones in the "bottom layer" are sharp.
My scanner has the same problem, hence it's only good for raw coins. A slab keeps a coin just far enough off the glass to render it out of focus.
The problem is you have a decent scanner. The better scanners do a good job of keeping the focus right on the plane of the glass with a very shallow depth of field. So the coin, being a little ways above the plane of the glass, is out of the focal range and is blurry. The older cheap scanners had a deeper depth of field and the coins were still in focus. I had a old cheap scanner that did a great job scanning slabs,but when I switched to a new faster computer with XP two didn't speak well with each other. So I go a new better quality scanner and the slab image quality went in the toilet.
