Epsion 4990 best resolution?

[neil poulsen]

. . . Remember, the negative is mounted on the underside of the mounting station, i.e. the side that has the spacers. To mount, you pour a small puddle of mounting fluid on the mounting station, place the negative over the fluid, and gently push or roll the fluid to the edges to remove all of the bubbles. Then tape the negative on all four sides, using a tape that will not leave residue. I use the blue-line masking tape that is available at home supply stores like Home Depot and Lowes. Wipe away excess fluid so it will not drop on the scanner glass. . . .

Sandy,

Do you mount with the emulsion facing the scanning glass, putting the fluid on the reverse side of the emulsion? That would prevent the image from passing through the mylar base. It would also keep the fluid away from the emulsion. Even though I'm sure the fluid is designed not to hurt the emulsion, I like the idea of having the fluid on the opposite side. Not so sure about placing the tape on the emulsion side though, even if only at the corners.

How does mounting the extra piece of mylar improve the image? I would have thought that the less between the emulsion and the scanning sensor, the better. (Whole reason for mounting on the underside of the glass.)

Thanks for the info and the tip on Doug Fisher's system. It looks like a good investment.

[sanking]

Sandy,

Do you mount with the emulsion facing the scanning glass, putting the fluid on the reverse side of the emulsion? That would prevent the image from passing through the mylar base. It would also keep the fluid away from the emulsion. Even though I'm sure the fluid is designed not to hurt the emulsion, I like the idea of having the fluid on the opposite side. Not so sure about placing the tape on the emulsion side though, even if only at the corners.

How does mounting the extra piece of mylar improve the image? I would have thought that the less between the emulsion and the scanning sensor, the better. (Whole reason for mounting on the underside of the glass.)

Thanks for the info and the tip on Doug Fisher's system. It looks like a good investment.

Neil,

I fluid mount with the mylar base facing the glass, and the emulsion down facing the CCD. I have found no problem in taping the emulsion side down with the blue-line tape as the tape does not leave any residue.

The theory behind fluid on both sides is that it fills in between the grain on the emulsion side, and fills in small scratches on both sides. This minimizes the amount of corrections that have to be done in Photoshop, and minimizes grain. However, minimizing grain is not much of an issue with LF film, though it may be with roll film and 35mm.

Sandy

[Jiri Vasina]

Sandy, surely the "resolution" in the direction of movement of CCD (or whatever) is dictated by the stepper motors. No doubt. But in the line arrangement of the sensors, they do not move, and in this direction they do have a physical resolution. And as you usually want square pixels (no distortion ) - no setting of different resolution in each direction - it's reasonable to omit the stepper motors from resolution judgments...

But from what I get we agree on one think - to scan in higher resolution and then downsample with whatever program/algorithm is appropriate (could be PhotoShop with it's bicubic algorithms...)

[Rider]

But from what I get we agree on one think - to scan in higher resolution and then downsample with whatever program/algorithm is appropriate (could be PhotoShop with it's bicubic algorithms...)

It may have been a good a idea back in the day when 300 spi was the max, but not now that your major issues are focus, film flatness and the like. At least that's what I've read here and elsewhere.

[David Luttmann]

It may have been a good a idea back in the day when 300 spi was the max, but not now that your major issues are focus, film flatness and the like. At least that's what I've read here and elsewhere.

I'm not sure where you've read that it is good to scan at the same size you are printing for....but I can tell you that flatbeds benefit from scanning at higher resolutions and downsampling from there.

[Rider]

I'm not sure where you've read that it is good to scan at the same size you are printing for....but I can tell you that flatbeds benefit from scanning at higher resolutions and downsampling from there.

I didn't say that all. I started this thread to find out what the optimal resolution for this scanner is. Epson says it's 4800x9600. I found that very doubtful. Consensus seems to be around 2000 spi max. I don't understand the reasons fully, but it seems reasonable when you're scanning through glass and not even focussing properly, that the extra bits will be more or less superfluous at some point. Basically, 4800x9600 is marketing hype, which is fine--they all do it.

[sanking]

I didn't say that all. I started this thread to find out what the optimal resolution for this scanner is. Epson says it's 4800x9600. I found that very doubtful. Consensus seems to be around 2000 spi max. I don't understand the reasons fully, but it seems reasonable when you're scanning through glass and not even focussing properly, that the extra bits will be more or less superfluous at some point. Basically, 4800x9600 is marketing hype, which is fine--they all do it.

I am somewhat confused by the term "optical resolution" as used by others so I always test for my own purposes with a high resolution lppm target. What I have found is that the Epson 4990 is capable of maximum resolution of about 35 lppm, if you scan at 4800 dpi. You will get *almost* as much real resolution scanning at 2400 dpi as at 4800 dpi (and at great savings in disk space), so for all practical purposes there is no reason to scan at a dpi of more than 2400 with LF film.

Compared to other Epson consumer scanners the 4990 gives a tad more resolution than the 4870, and a tad less than the V700 and V750. For scanning LF film the difference between these scanners in resolution is of little or no consequence IMO.

Sandy King

[Frank R]

I always test for my own purposes with a high resolution lppm target.

Which target do you use? Where can I get one?

[sanking]

Which target do you use? Where can I get one?

I use a chrome on glass 3X3" USAF target, bought from Edmund Optics. The target is available as both a positive and negative. Edmund also sells less expensive 2X2" targets of the same type.

These targets test resolution up to about 225 lppm, well beyond the limits of most scanners.

The results are not industry standard, but they are useful in a relative sense when comparing different scanners.

Sandy

[Stephen Sample]

Hi, I have two questions. How much better is the Fischer Dry mount system than the Wet Mount sytem? If I use the wet mount scanning on my Epson 4990, does anyone know how to clean up the negative after it has been wet mounted? Does the wet mount ruin the negative for future scanning? Maybe there is a web page that describes the cleaning of the negative? Thanks. This was a wonderfully helpful thread!