newtons rings on 4x5 scans

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I am scanning 4x5 transparencies with an HP5370c scanner. I believe I need to use a piece of glass to get the film to lay flat. The scans are of better quality than expected, however, I am getting what I believe are called newtons rings. I also believe this is due to the quality of glass? Is there something I can use, or a specific grade of glass I can purchase to solve this problem?

Thanks- Jon

-- Jon paul (jonpaul@775.net), September 09, 2001

Answers

Hi Jon, I don't use glass over the film but place a piece of plastic corrugated mailing stiffener card over it. The card is cut out slightly larger than the film being used and holds the film flat. I don't know whether you use a special tranny hood, but I simply place a decent lightbox on the mailing card.

Clive

-- Clive Kenyon (clivekenyon@hotmail.com), September 09, 2001.


Make sure you always place the emulsion side towards the glass. Unless there are large low density areas, NR should be very limited so. Moisture in the air is another factor. The dryer, the least NR.

-- Paul Schilliger (pschilliger@smile.ch), September 10, 2001.

This is a common problem when scanning transp. or negatives on a flatbed scanner. The problem is caused by the contact of the film to the glass of the scanner. Many scanners come with holders for your particular film that seperates the 2 surfaces ever so slightly (or you can make one yourself from some thin card stock). I've tried to reposition transp.'s by flipping onto the emulsion side and have still experienced the "rings". Some people also use a gel like substance to "float" the film on the scanner, but I have never used the stuff (I know they use it on drum scanners sometimes)and I've also heard of an anti-newton spray. I've found a wealth of information on this subject on the web at various scanner/digital related sites. Good Luck.

-- Eric N. Blevins (eblevins@moh.dcr.state.nc.us), September 10, 2001.

Get out your screwdriver and dismantle your scanner (stick with me onm this one!) measure the glass and go down to your local picture framer and get him to cut the exact size out of some non reflective glass (this has matt etched surface on one side) if he has a few different types get the least etched. Also get him to cut a smaller bit the same size as a 4x5. Most scanner glass is held in with double sided sticky tape - carefully prize the original out and replace with your new glass (etched side to the film) put it back together and you can now sandwich your film between the etched surfaces and eliminate Newtons rings - I did this to my Epson 1640SU - cheap (30), simple (no messing with frames or oils) and effective (I get repro quality scans from 5x4 trannys with a bit of post production in PS) I'm looking to get a Canon 2400 scanner soon -I hope they don't stick the glass in too well!!

-- John Griffin (john.griffin@millerhare.com), November 06, 2001.

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