Vertical streaks on Epson scanner

I recently bought an Epson 1640XL for scanning darkroom prints. I did a test scan without anything on the scanner to get an idea of glass condition and sensor (screenshot attached). The glass obviously needs some cleaning, the newton rings are a result of no media in the scanner, but i did also notice vertical streaks running down the entire scannable area.

The darkroom I print at has a newer Epson 10000XL that I used for scanning until I noticed similar streaks on my prints - the owner tested in the same manner. It hasn't been fixed and no one seems to complain about it.

I've read there are calibration strips (atleast for the 10000xl) under the glass that can cause several scanner issues once they become dirty.

Has anyone experienced these streaks and knows the source of the issue?

Most scanners I have worked with in the past have a component in the calibration phase called "Pixel leveling" that applies an algorithm to each sensor of the line array to "level" the light output and create a uniform scanning field. Depending upon where the calibration target is, there might be dirt on the target that upsets this calibration phase. The calibration patches on the Epson flatbeds I own are on the film holders themselves, but I don't know where they are on either of the scanners you mention...

Kino said:

Most scanners I have worked with in the past have a component in the calibration phase called "Pixel leveling" that applies an algorithm to each sensor of the line array to "level" the light output and create a uniform scanning field. Depending upon where the calibration target is, there might be dirt on the target that upsets this calibration phase. The calibration patches on the Epson flatbeds I own are on the film holders themselves, but I don't know where they are on either of the scanners you mention...

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Would that imply "pixel leveling" is only used during scanning of negatives? I only use this for scanning media and the test scan was done using Vuescan with reflective setting.

It might not show up on a transparency. Only a test will prove it.

Pixel leveling, as I understand it, is common to any form of line array scanning calibration. However, it may be that the targets used to calibrate the reflective function is internal to the scanner (lower section) and the transparency adapter target could be different.

One or both may be dirty.

The scanners need a thorough cleaning of the optical path. Bed glass top and bottom, mirrors, lens, and in the worst case the sensor. Removing the sensor board for sensor cleaning requires recalibrating the sensor position to get a uniform scan and is not recommended for the average user to do. The bed on the other hand is fairly easy to open to clean the underside of the bed glass, mirrors, lens front. Care must be taken to keep the inside of the scanner dust free. Newer Epson scanners have the mirrors, lens, sensor sealed in a block that has to be replaced if there is a problem.

Kino said:

It might not show up on a transparency. Only a test will prove it.

Pixel leveling, as I understand it, is common to any form of line array scanning calibration. However, it may be that the targets used to calibrate the reflective function is internal to the scanner (lower section) and the transparency adapter target could be different.

One or both may be dirty.

Click to expand...

That's what I was thinking, the darkroom owner mentioned an internal calibration target for the 10000xl and this model is its predecessor.

shutterfinger said:

The scanners need a thorough cleaning of the optical path. Bed glass top and bottom, mirrors, lens, and in the worst case the sensor. Removing the sensor board for sensor cleaning requires recalibrating the sensor position to get a uniform scan and is not recommended for the average user to do. The bed on the other hand is fairly easy to open to clean the underside of the bed glass, mirrors, lens front. Care must be taken to keep the inside of the scanner dust free. Newer Epson scanners have the mirrors, lens, sensor sealed in a block that has to be replaced if there is a problem.

Click to expand...

Good to know. I will avoid the sensor board for now, hopefully cleaning the rest of optical path will help with this issue. Do you have any idea of where the internal calibration target might be on the Epson scanners? I'm assuming it will be to the left (looking from front of unit) since thats where the lens assembly sits during standby.

jvonoldershausen said:

Do you have any idea of where the internal calibration target might be on the Epson scanners?

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I do not know where the target is.

The calibration target was on the underside of the left edge ruler after removing the glass.

There wasn't much debris or discoloration and no real way for dust to get in between. I cleaned the underside of the glass really well and then spent a while cleaning all the mirrors inside the unit which were coated in a very uniform layer of dust. Also cleaned the lens glass carefully. Things actually got worse at first but with a second cleaning there was a huge improvement. Took a comparison of the V850 @ 600 dpi (no focusing feature) and the 1640XL @ 600 dpi (focus enabled) - big difference in sharpness.

I had been waiting to find a reasonable used 10000xl but this already blows away the V850 (for reflective scanning). Definitely much slower than the V850 with scanning @ 600dpi but considering I have to do two scans for every one 11"x14" print on the V850 and also go through a photo stitch workflow on photoshop, it works out to the same amount of time with a sharper end result.