Anti-Newton Glass

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Anti-Newton Glass

Postby Julian Boulter » Sat Dec 26, 2009 12:27 am UTC+00:00

Hi all,

Anyone know where I can source AN glass from in the UK to cover 10x8 on my 4990 scanner?

I purchased AN glass from these guys:

http://www.knightoptical.co.uk/acatalog ... nGlass.htm

Nice, company, cut it to size, thought it was my ideal solution to get around curling negatives on the glass but no matter what I do I always get newton rings with this glass. They said they had never had that problem before but would offer a refund but I'm in a hole now, tons of scanning to do and no solution.

And berfore you ask, I was scanning the correct way, I previously had a dry mounting kit from Doug (which I sold when I went 10x8) and that had a nice piece of AN glass for 4x5 which scanned beautifully.

Happy New Year.

Julian
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Re: Anti-Newton Glass

Postby DJ » Sat Dec 26, 2009 12:37 pm UTC+00:00

I assume you are scanning the 8x10 directly on the flatbed glass?

The 4990 iirc is a single lens scanner ( unlike the V700/750 which are dual lens ) and the lens focal point is usually set just above the glass ( and varies wildly from unit to unit ). So scanning an 8x10 with the 4990 ( or V700/750 for that matter ) means scanning on the flatbed glass, the 8x10 "holder" provided with the V700/750 scanners is merely a plastic film "frame" you place around the edges of the film to try to keep it flat. I've never scanned 8x10 film on mine, but suspect it does a less than perfect job of keeping it flat.

I strongly suspect the newton rings you're seeing are from the scanner flatbed glass, not the AN glass.

One suggestion, from model shops you can buy (poly)styrene sheets ( not the foamy packing stuff, but sheets of plastic like paper ) in black. You can buy these in various thicknesses, from 0.5mm to 2mm. I used these to make shims for my V750 for wet-scanning. Buy a few sheets of these, they're very cheap, and make up an 8x10 "window" and stack them up to the height of your focus depth, then place the film on top and the AN glass on top of that ( if you still have it ). This should hopefully keep the film the right focal distance from the flatbed glass whilst (hopefully) keeping the film itself off the glass. Your main problem will be the film bowing in the middle due to it's size, and you'll have to make the "window" slightly smaller than 8x10, but I can't think of anything else that will keep it flatter, aside from wet-mounting.

p.s. I believe Doug does also sell an 8x10 AN glass, although he has limited stock of it.
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Re: Anti-Newton Glass

Postby jb7 » Sun Dec 27, 2009 12:25 pm UTC+00:00

I use a 750, and I found that the correct focus for 8x10 film was just above the glass-
If your ANR glass is large enough, you could tape your neg to it, then suspend the sandwich, film side down,
over the scanning bed-

A coin (pennies might work) in each corner will lift the neg off the bed;
you'll need to test to find the correct height-

I don't use the anr glass, but picture framing glass, with a slight texture, works fine...
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Re: Anti-Newton Glass

Postby timparkin » Sun Dec 27, 2009 1:12 pm UTC+00:00

jb7 wrote:I use a 750, and I found that the correct focus for 8x10 film was just above the glass-
If your ANR glass is large enough, you could tape your neg to it, then suspend the sandwich, film side down,
over the scanning bed-

A coin (pennies might work) in each corner will lift the neg off the bed;
you'll need to test to find the correct height-

I don't use the anr glass, but picture framing glass, with a slight texture, works fine...


I do this taped, hanging upside down process and it works very well.. I use the betterscanning kits AN glass

Tim
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Re: Anti-Newton Glass

Postby Julian Boulter » Mon Dec 28, 2009 12:30 am UTC+00:00

Thanks for all the replies,

I strongly suspect the newton rings you're seeing are from the scanner flatbed glass, not the AN glass.


No its not that, if I place the film on the glass glossy side down I get no newton rings (just curling corners), I know this should work because it worked fine with the smaller glass I had e.g. film on the scanner glass glossy side down with AN glass on top.

I'm not that concerned about the optimum position for the scan really, and I tried tape but I like the film borders scanned and it just looks really messy + it never holds truly flat, I just want a quick scan, if everything is slightly out of optimum focus together, I can sharpen, I just don't want different areas of the film at different sharpnesses, hence the glass.

I might try to see if Doug can source the same glass for me in the bigger size.

Happy New year all.

Julian
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Re: Anti-Newton Glass

Postby Julian Boulter » Tue Dec 29, 2009 10:22 pm UTC+00:00

the 8x10 "holder" provided with the V700/750 scanners is merely a plastic film "frame" you place around the edges of the film to try to keep it flat


Hadn't realised the 700 scanners came with this for 10x8, my 4990 does not, wondering if they are compatible, may not be ideal as I like scanning the film borders too but if anyone has one and is not planning to use 10x8 I would be interested in buying it.

Cheers

Julian
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Re: Anti-Newton Glass

Postby Joanna Carter » Tue Dec 29, 2009 11:12 pm UTC+00:00

Julian Boulter wrote:Hadn't realised the 700 scanners came with this for 10x8, my 4990 does not, wondering if they are compatible, may not be ideal as I like scanning the film borders too but if anyone has one and is not planning to use 10x8 I would be interested in buying it.

This "holder" is simply a piece of black plastic with a 10" x 8" hole in it and a slot at the end for calibration. You might as well get a sheet of black modelmaking plastic and cut it to suit, making sure that you cut the calibration area into the end of the sheet to match that of your other holders.
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