RE: filmscanners: 6x8

["Wilson, Paul" <PWilson@gomez.com>]

One more MA person.  I'm in Chelmsford and work in Waltham.  I didn't know
Polaroid has offices in Wayland.

Paul Wilson

> -----Original Message-----
> From: Hemingway, David J [mailto:HEMINGD@POLAROID.COM]
> Sent: Saturday, December 01, 2001 2:30 AM
> To: filmscanners@halftone.co.uk
> Subject: RE: filmscanners: 6x8
> 
> 
> Bruce,
> We are nearly neighbors!! I live in Duxbury and work in Wayland
> 
>  -----Original Message-----
> From:         Bruce Kinch [mailto:pvx@ma.ultranet.com] 
> Sent: Saturday, December 01, 2001 12:24 AM
> To:   filmscanners@halftone.co.uk
> Subject:      RE: filmscanners: 6x8
> 
> >There should not be as we are using Newton free glass as one 
> of the two
> >pieces. Why only one is Newton free I frankly don't know but 
> I am told that
> >is all that is necessary.
> >David
> 
> Newton rings are an interference cancellation from light trying to 
> get through two transparent but reflective surfaces that are less 
> than a wavelength apart.
> 
> Anti-Newton glass is very slightly rough or textured. The AN glass 
> normally is used only on the base (top) side of the film. Most roll 
> film, esp 35mm, has a shiny base, partly to reduce scratches during 
> film advance I presume, but that makes it prone to the problem. Most 
> sheet film has a "retouchable" surface, with enough "tooth" that a 
> pencil can be used, and that alone eliminates Newton Rings. The 
> emulsion side of any film is itself sufficiently rough to not need AN 
> glass. Besides, if used between film and optics, AN glass would 
> degrade the image.
> 
> Dust is less of a problem than it might seem (most is out of focus), 
> and is worth noting that you may not need any glass on the bottom at 
> all, if the film is supported by the carrier on all four sides. The 
> Leica Ic enlarger was (and still is) legendary for it's image 
> quality, and it used a single condenser lens directly atop 35mm film. 
> They later sold a special AN glass that slipped under the condenser 
> when the problem became apparent with modern films. As an aside, I've 
> refurbed a couple of these for friends, and as the AN attachment is 
> impossible to find used, I have used slide mount AN glass or an 
> unmounted soft-focus filter as substitutes-they worked perfectly.
> 
> Old timers used to buff glass enlarger carriers with "Jeweler's 
> Rouge", an ultrafine abrasive. No need to today. I've had students 
> make AN glass carriers for years, using "non-glare" picture framing 
> glass on top, and plain below, with a tape hinge. Amazing how much it 
> improves sharpness in conventional printing. Probably do the same in 
> a scanner. In fact I may make one for my 4000SS before David does:-)
> 
> 
> 
> 
> -- 
> Bruce C. Kinch
> Associate Professor of Photography
> The Art Institute of Boston at Lesley University
>