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#1
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AN (Anti-Newton) glass question
The Focomat IIa uses AN glass for the top glass, and plain for the lower.
Is this a universal principle? IOW, can I presume the same for any two-glass carrier? |
#2
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AN (Anti-Newton) glass question
In article , jjs wrote:
The Focomat IIa uses AN glass for the top glass, and plain for the lower. Is this a universal principle? IOW, can I presume the same for any two-glass carrier? The Matte surface of the AN glass has to be above the negative. -- Reality is a picture perfected and never looking back. |
#3
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AN (Anti-Newton) glass question
jjs wrote in message ... The Focomat IIa uses AN glass for the top glass, and plain for the lower. Is this a universal principle? IOW, can I presume the same for any two-glass carrier? What I have heard is that the Anit-Newton glass is against the smooth base side of the negative, and you can use plain glass against the rougher emulsion side of the negative. I don't know if this is a fact or not; I use glassless neg carriers. |
#4
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AN (Anti-Newton) glass question
On Mar 16, 5:09*pm, jjs wrote:
The Focomat IIa uses AN glass for the top glass, and plain for the lower. Is this a universal principle? IOW, can I presume the same for any two-glass carrier? Yes, as long as it is an anti-newton negative carrier. Plain glass carriers will have plain glass on both sides. This would be the time you would get the "newton rings" on your print around the highlights. Right? Draco |
#5
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AN (Anti-Newton) glass question
On 3/19/2008 12:54 PM Draco spake thus:
On Mar 16, 5:09 pm, jjs wrote: The Focomat IIa uses AN glass for the top glass, and plain for the lower. Is this a universal principle? IOW, can I presume the same for any two-glass carrier? Yes, as long as it is an anti-newton negative carrier. Your reply is a tautology. If the carrier has anti-Newton glass in it, then it's an anti-Newton negative carrier. Plain glass carriers will have plain glass on both sides. This would be the time you would get the "newton rings" on your print around the highlights. I think the OP knows this. |
#6
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AN (Anti-Newton) glass question
"Draco" wrote in message ... On Mar 16, 5:09 pm, jjs wrote: The Focomat IIa uses AN glass for the top glass, and plain for the lower. Is this a universal principle? IOW, can I presume the same for any two-glass carrier? Yes, as long as it is an anti-newton negative carrier. Plain glass carriers will have plain glass on both sides. This would be the time you would get the "newton rings" on your print around the highlights. Right? Draco Newton's rings are an interference pattern where two beams of light can interfer. The usual cause is reflection between two reflective surfaces that are very closely spaced. In the case of an enlarger using a glass sandwich negative holder the two surfaces are the support side of the film and the glass next to it. By making the glass slightly rough the reflection is broken up and the rings are not formed. Newton's rings can be formed on the emulsion side too but the emulsion is usually rough enough, or the amount of reflection from the gelatin low enough, so that rings are not produced there. Newton's rings appear as somewhat uneven dark and light concentric rings all over the image. They follow approximately any lack of flatness in the two surfaces involved. Newton's rings are often used to measure the degree of conformance of two closely spaced surfaces where one of them is transparent as when testing the figure of a lens against a standard. I think the effect you are referring to is halation. This is also caused by reflection, usually in film, where bright areas are reflected back into the emulsion by the support. All modern film has either a light absorptive coating on the back or in a layer under the emulsion (the usual method for color film) to eliminate halation. Halation was a very serious problem with early glass plates where it formed quite noticeable halows around bright objects and reduced the contrast of more extended bright objects. Glass plates were also coated with anti-reflective layers on the back. It is usual for the anti-halation layer to be removed mechanically (as in the Remjet used for Kodachrome and some motion picture stocks) or for the dyes it contains to be made colorless by the sulfite in the developer or fixing bath. -- --- Richard Knoppow Los Angeles, CA, USA |
#7
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AN (Anti-Newton) glass question
Yes, as long as it is an anti-newton negative carrier.
I'm glad that was brought up. Quite frankly, I just presumed the negative carrier in question would need anti-newton glass. I will describe it and perhaps someone can enlighten me. The glass is for the Saltzman 8x10 enlarger. The carrier works with two plates of glass (exactly 8x10") to sandwich the negative. There is nothing whatsoever to separate the glasses, except the negative. One removes the lower glass, does what he can to remove dust, replaces the glass, and swings four tension clips over the edges of the glass. Requires AN glass, no? Thank you all! |
#8
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AN (Anti-Newton) glass question
In article , jjs wrote:
Yes, as long as it is an anti-newton negative carrier. I'm glad that was brought up. Quite frankly, I just presumed the negative carrier in question would need anti-newton glass. I will describe it and perhaps someone can enlighten me. The glass is for the Saltzman 8x10 enlarger. The carrier works with two plates of glass (exactly 8x10") to sandwich the negative. There is nothing whatsoever to separate the glasses, except the negative. One removes the lower glass, does what he can to remove dust, replaces the glass, and swings four tension clips over the edges of the glass. Requires AN glass, no? Thank you all! Ok for you, I just pulled my Omega 10x10 carrier out of the enlarger and it has two sheets of standard optical glass but not AN. To my knowledge AN appears with a Matte surface unlike standard optical grade glass. It (AN) will look less than perfectly clear. Imop & Perhaps Richard K. can corroborate AN is only needed with a Condenser housing, I have an Omega diffused Halogen one of three known to exist. -- Reality is a picture perfected and never looking back. |
#9
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AN (Anti-Newton) glass question
In article ,
"Richard Knoppow" wrote: Newton's rings are an interference pattern where two beams of light can interfer. The usual cause is reflection between two reflective surfaces that are very closely spaced. Does a single original beam source that is split, connote two beams? If so my guess is that, Propagation seems to be the correct term? -- Reality is a picture perfected and never looking back. |
#10
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AN (Anti-Newton) glass question
jjs wrote in message ... Yes, as long as it is an anti-newton negative carrier. I'm glad that was brought up. Quite frankly, I just presumed the negative carrier in question would need anti-newton glass. I will describe it and perhaps someone can enlighten me. The glass is for the Saltzman 8x10 enlarger. The carrier works with two plates of glass (exactly 8x10") to sandwich the negative. There is nothing whatsoever to separate the glasses, except the negative. One removes the lower glass, does what he can to remove dust, replaces the glass, and swings four tension clips over the edges of the glass. Requires AN glass, no? Thank you all! Do you get Newton's rings? If so AN glass will eliminate them, if not then don't bother. BTW, I suspect glass with anti-reflection coating on it similar to a lens would accomplish the same purpose. -- --- Richard Knoppow Los Angeles, CA, USA |
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