trouble with anti-newton's ring glass?

So, I picked up a sheet of anti-newton's ring glass because I'm sick and tired of the newton's ring artifacts that I'm getting :)

Well, no matter how I set it up (film on either side of the glass, glass flipped over, layed flat on the scanner glass, suspended above the scanner glass, and so on) I keep getting strange dark bars through my scans. At the worst, it's a very crisp dark band through the middle. At the least, it's a dark band on one (or both) edges of my scan. It's usually somewhere near the middle of the image. I tried lifting up one side of the plate higher than the other side, and that seemed to minimize the band, but it's still there.

I'm guessing it some sort of reflection (since I'm scanning negatives, what the scanner is seeing before it's inverted is a brighter band, not a darker one)

So, is there any solution to this? I never saw this while using the 'better scanning' film holder and glass for my 120 film, but there are no holders made for 8x10 film on the Epson 4990.

This is really frustrating me, and I'm completely bummed out about this. I had been waiting for a chance to order and use some of this anti-newton's ring glass for my 8x10 film, but now the problem is even worse than newton's rings (good news is, I'm getting no rings, haha!) I get great results with my 4x5 scans (in their holders), but I enjoy shooting with the 8x10 camera so much more! I don't really want to start wet scanning, and I can't afford to have my stuff drum scanned. Is there any solution?


http://404photography.net/wip/scan_problem_01.jpg

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Originally Posted by Daniel_Buck

... I keep getting strange dark bars through my scans...

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This looks like the problem of a mark in the prescan area of the film holder (the cutout at the top edge). Check to see if there is anything on the glass there.

In addition to Joanna's comment about keeping the calibration area clean and free of anything covering it, are you using your "film area guide" that came with the scanner? If not, this can cause you to get those bars.

Doug
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www.BetterScanning.com

I'll clean the glass and make sure there is nothing near the top edge.

Yes, I'm using the "film area guide" below the anti newton's ring glass.

Thanks for the replies, I'll give it another try tonight!

alright, I did a real quick test before I head out to work, it appears that possibly I had part of the AN glass sticking out above the 'film area guide' notch. My quick test looked good, I'll do a another few tests when I get home tonight. Thanks yall! Much appreciated!

On a side note, what the heck is that black bar anyway? I don't understand? With the film area guide, shouldn't it just scan the entire glass regardless?

Yes, thank you thank you! It's working now, no newton's rings, and no black band!

It's working, but I don't know WHY it's working. As in, what was the problem? If something blocks the top area of the "film area guide", why does it put strange black bars through the image? I don't understand that.

Thanks for the replies, both you you!

As i understand it, the scanner makes a short pass initially over that are to calibrate how it will record the brightness of the cathode ray tube. The brightness over the length of the tube varies slightly so it compensates with the software interpolating light and dark areas to make them uniform. Dust dirt etc. in this area throws off the calibration and causes it to incorrectly compensate in those areas causing light or dark streaks corresponding to that area of the cathode ray tube.

ahh, that makes sense, thanks kirk :-)