Scanning Discussion - Epson 4870 (4990)

At long last a high resolution, reasonably priced flatbed scanner has been released. Many people are wondering how it stacks up to other options. This discussion compares a prior flatbed model and the latest dedicated film scanner to provide a range of choices. The image at right is the full frame of a standard test film. Although it is a black and white original we scan using RGB to highlight color problems with the scanner's ccd array or lens. Note that in the following images, the ragged appearance in the center of the circle is in the test film itself.	Full Frame Test Slide
We will concentrate on the small circle in the lower left. Here is that portion as scanned by the Minolta 5400. If you have a fast online connection you can click on the image to see the full-size version. Remember when viewing the larger images that some browsers shrink the image to fit the screen. The image is pretty sharp and there is no sign of color fringing. It is presented without any sharpening or other adjustment.	Scanned with Minolta 5400 (click image for full-size version)
Here is the same portion scanned in with the Epson 4870 at 4800 dpi. The small image is reduced to the same size as the one above, so it's not suitable for making critical comparisons. The full-size image can be viewed as above. It can be seen that it is not as sharp as that above, however that's not the full story.	Scanned with Epson 4870 (click image for full-size version)
As can be seen in other discussions, it is perfectly proper to sharpen scanned images to compensate for diffusion of fine detail by the sampling process. Here is the same sample after using the unsharp mask feature in Photoshop. For reference the parameters were a threshold of 1, a radius of 4.8 (corresponding to 1/100 inch) and an amount of 200%. It now looks almost as good as the Minolta scan! There is a little coloration in the center of the circle which indicates a small amount of aberration.	Epson 4870 after sharpening (click image for full-size version)
Remember that using either of these scanners at their full resolution is seldom necessary. With 35mm film the Minolta will yield an 18x enlargement or about an 18x27 inch print. The Epson 4870 will yield 16x enlargement or about 16x24 inch print. It takes careful shooting to create an original that will look good with this much magnification. So lets look at the results at a more typical degree of enlargement. For this comparison we introduce an extra scan made with an older Epson 1600 dpi scanner. Here is the scan at 1600 dpi without and with a suitable amount of sharpening. The coloration in the center is not a jpeg artifact, but is color aberration in the scanner. This resolution will yield about a 6x8 inch print.	1600 dpi scan 1600 dpi scan after sharpening
This is the Epson 4870 scan after sharpening and reduced to 1600 dpi. Better than the one above, but not as much as you would expect after looking at the original 1600 dpi scan. After all this scanner has at least three times the resolution of the model above.	4870 sharpened scan at 1600 dpi
This is the Minolta 5400 scan without sharpening and reduced to 1600 dpi. Best yet, but not as much as you might expect from a scanner that has about 3.5 times the resolution of the 1600 dpi scanner (and the actual resolution is probably more since the 5400 seems to achieve its rated specifications while the flatbed scanners don't). The moral of this is that the Epson 4870 will satisfy just about any user who is scanning medium or large format film and will meet the requirements of many 35mm users who need prints in the 8x10 to 11x14 range.	5400 scan at 1600 dpi
Here is a real world example, as several viewers have requested. This is the full frame from a 35mm color negative.	Minolta 5400 full frame
This is the same image as above, but the area just beyond the edge of the building is shown at 100% in this screen grab. Notice the detail resolved by the Minolta scan, not only in the street sign, but in the bricks behind. There is also grain apparent in the sky.	Minolta 5400 at 100%
Here is the same area as scanned by the Epson at 4800 dpi. It is shown at 100% with a minimal amount of jpeg compression. There is obviously less detail. And the differences are more than just going from 5400 dpi to 4800 dpi.	Epson 4870 at 100%
Finally, here is the same section with unsharp mask applied using the same settings as for the test negative above. This is better, but no match for a dedicated film scanner. It pays to keep things in perspective, go back and look at the full frame to see what a small part of the image this represents. With reasonable degrees of enlargement this will make a satisfactory print. So, to repeat the conclusions above, this scanner will be excellent for medium and large format film and acceptable for normal use with 35mm. For those with a 2400 dpi or 3200 dpi flat-bed scanner, the question is whether to upgrade. In my opinion, if you create 6x to 8x enlargements from 120 size film or larger, and don't need the IR cleaning capability provided by digital ICE, then there is little reason to switch. As can be seen from the examples above, even a 1600 dpi scanner shows little difference as long as final magnification is kept within it's range. If you need to enlarge more than 8x or do a significant amount of cropping there may be a modest improvement in inkjet print sharpness. This model is not a quantum leap over the previous ones, but an incremental improvement with the addition of the cleaning options.	Epson 4870 at 100% - sharpened
Update Since both the Epson 4870 and 4990 have 20,400 by 2 sensor arrays it is believed that this discussion will apply equally well to both models. The new model is supposed to scan faster and has an external scan indicator as well as a slightly different software package and a larger transparency area.
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Robert D Feinman

Comparison of the Epson 4870 (4990) to other scanners