Transparency scaning - why emulsion side up?

[pasiasty]

When dealing with some unexpected artefacts (see another thread), I also tried to adjust focus. The best results I got scanning it emulsion down. Actually, it is quite logical - the image, as seen by sensor, is not covered by film, which disperse light a bit. But why Epson suggests scanning them emulsion side up?

[welly]

I've always scanned emulsion side up, as you say recommended by Epson and never tried the other way round. Never questioned why, actually but may try the other way round. I can only imagine it might be something to do with reflections off the shiny side?

[Greg Lockrey]

I scan with emulsion side down with my Epson 10,000xl. I seem to get a better control of sharpness. The only reason I can see with emulsion side up is to get "right reading" of the negative... which you can easily flip in PS or other print editing programs.

[Steve Smith]

As the light has to pass through the film, it shouldn't make any difference.


Steve.

[pasiasty]

Sure the light has to pass through, but it may matter on which side the image is: imagine the film is not clear, instead it looks more like paper, but you still use it as transparency; if you put image (emulsion) side to the light, what you can see from the other side is blur; if put otherwise, the image looks clear. Of course the film is much clearer, but it still diffuses a bit.

[Walter Calahan]

might have to do with Newton Rings, just speculating

[rdenney]

I'm speculating, too. But I bet it's not anything so esoteric as Newton Rings, and it's something mundane like getting a right-reading image. It's a consumer scanner, after all. They probably didn't want support calls like, "My images are all backwards. What's wrong with your scanner?"

Rick "not looking past the obvious" Denney

[Heroique]

I’ve noticed that the illustrations at Betterscanning show base side (not emulsion side) on glass – that is, base side on the underside of the mounting glass, which sits above the scanning glass.

(The film notches above the white glove indicate emulsion side is “up.”)

I’ve done it both ways, and my personal results are best the opposite way – emulsion side on glass – but others here w/ reasons of their own prefer base side on glass, like the photo below.

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More critical, of course, is to tape the film sheet on the ANR (etched) side of the mounting glass – and if dry mounting, use more than four pieces of tape! I usually use at least 6 or 8 pieces to better ensure flatness.

[chuck94022]

When dealing with some unexpected artefacts (see another thread), I also tried to adjust focus. The best results I got scanning it emulsion down. Actually, it is quite logical - the image, as seen by sensor, is not covered by film, which disperse light a bit. But why Epson suggests scanning them emulsion side up?

In my opinion, this is more likely due to closer proximity to the plane of sharpest focus. I've scanned emulsion up and down and not noticed a difference in image quality.

But if you are using the standard holders and the film has curl, it won't be flat in the holder edge to edge. The curl could bring the center either up or down, and flipping the film over will alter the position of the center slightly. Slightly is all you need with the Epson's very narrow DoF.

First thing I'd do is shim to find the best focus, and I'd seriously consider an alternative to the standard holders to keep the film flat.

I use the betterscanning mounting system, and have very recently concluded that for small formats, especially 35mm, wet mounting with Kami fluid is the fastest and easiest way to mount that assures real edge to edge flatness. It's faster than taping dry film, and leaves the rebate area uncovered so it can be scanned if desired.

I also use the Digitaliza holders, shimmed, for proofing. They hold better then the standard holders for medium format and 35mm. Not perfectly flat but not bad, and they are quick to use if the film isn't too curled.

I proof 4x5 using the Epson standard holder, because at that size I scan at much lower resolution and these issues are much less important. Final scans are wet mounted on the betterscanning holder.

[mdm]

I scan with emulsion wet mounted to the glass of a betterscanning holder. No need for mylar, half the dust, half the scanner fluid, all the advantages as far as emulsion scratches go, flat film, quicker and no residue frome tape, results seem good. I use a sheet of blotting paper over the negative with a quick gentle rollover from a rubber brayer to remove bubbles and excess scanner fluid. Infact, if you bow the neg and gently lie it on the fluid from one side to the other, holding the first side firmly in place, all the bubbles get pushed out and the rolling is merely a formality. Quick and simple. Works for me, but I am not printing 50x70.