anti Newton Glass

[David Jones]

Does the Durst style of anti newton glass for the neg carrier really spoil the image quality or is it a myth?
Thanks
Dave

 

[Martin Aislabie]

I'm not sure about Durst AN Glass but the effect of Newtons Rings on a print is cirtain - it goes in the bin

If you live in a climate where you're likely to have Newtons Rings - then you don't have much choice - either get some AN Glass or give up printing for those months when you are likely to encounter the problem.

I have never been able to see the effct of AN Glass on my prints but some others say they can tell

Martin

 

[ic-racer]

I have never heard that.
I have 4 glass carriers:

1 8x10 with Durst AN glass
1 4x5 with Omega AN glass
1 4x5 with "Focal Point" AN glass
1 6x7 with Omega AN glass

There is no noticable difference in the prints.

 

[Jarvman]

I have printed 6x12cm images with my durst with anti-newton glass and haven't experienced any problems. Likewise I haven't heard that one.

 

[Bob-D659]

AN glass can really show up when you put the negative in upside down with the emulsion up against it.

 

[Brad Dow]

My enlarger is a Durst L1200. When I was working with TMX, I noticed that the emulsion side is smooth enough to produce newton rings. I mentioned this to a very knowledgeable friend who managed a high-end custom lab. He said they use AN glass top and bottom for TMX and assured me the bottom sheet of AN glass was quite invisible. I couldn't believe him and tried to prove him wrong. Making careful comparison prints (AN top glass + AN bottom glass, clear bottom glass, or no bottom glass) the only visible difference among the three conditions was newton rings when the bottom glass was clear. No difference in contrast. No visible difference in texture, even at high magnification. One of my test negatives was a 6x9 inch exposure of clear blue sky. At the maximum magnification my enlarger is capable of with a 135mm lens there was still no hint of AN glass texture visible in the print.

 

[ic-racer]

BTW: my remarks were with respect to projection printing with diffuse light. Those people using condenser and point source enlargers may have a different experience with double or single AN glass.

 

[Brad Dow]

BTW: my remarks were with respect to projection printing with diffuse light. Those people using condenser and point source enlargers may have a different experience with double or single AN glass.

My results, by the way, were with the standard Durst condensers.

 

[ic-racer]

My results, by the way, were with the standard Durst condensers.

Thanks for pointing that out. I have not printed with a condenser enlarger since 1974, but I will be setting up an Omega D3 Condenser for a friend this week. He says it came with a glass carrrier, so we will plan on using that.

 

[RalphLambrecht]

Does the Durst style of anti newton glass for the neg carrier really spoil the image quality or is it a myth?
Thanks
Dave

Properly used, AN glass does not affect the image at all.

The AN glass goes on top of the negative, AN side down.
Negative below, emulsion-side down.
Regular glass below the negative is optional (improves flatness) but is not recommended with very smooth emulsions, such as Tmax.

 

[Ronald Moravec]

AN glass goes only on top side. Bottom is clear or no glass. All my Leica enlargers have AN top and I can not see a difference if I print with a glassless except for corners going out of focus because the neg is not flat.

Plain glass on the bottom does not make a difference.

Now 4x5 is even less magnification so there is no chance of seeing anything. My 4x5 carrieres are AN top only, plain glass bottom, or glassless.

NEVER use AN on the bottom. Guaranteed you will see it big time.

 

[Peter De Smidt]

Except that Howard Bond used AN glass for both the bottom and top glass plates in his enlarger, since some of the newer films have very shiny emulations, which can lead to Newton's rings. He has fairly high standards for image sharpness That said, AN glass varies in quality, and large enlargements are more likely to show up issues than small ones.

 

[Brad Dow]

AN glass goes only on top side. Bottom is clear or no glass. All my Leica enlargers have AN top and I can not see a difference if I print with a glassless except for corners going out of focus because the neg is not flat.

Plain glass on the bottom does not make a difference.

Now 4x5 is even less magnification so there is no chance of seeing anything. My 4x5 carrieres are AN top only, plain glass bottom, or glassless.

NEVER use AN on the bottom. Guaranteed you will see it big time.

It's counter-intuitive, but bottom AN glass, at least Durst AN glass in a condenser enlarger, will have no visible effect an any enlargement and is, in my experience a necessity for TMX. As I said before, this is something I extensively tested.

 

[Craig Swensson]

quote
If you live in a climate where you're likely to have Newtons Rings - then you don't have much choice - either get some AN Glass or give up printing for those months when you are likely to encounter the problem.

What is a climate likely to induce newton rings please? I have not read this in my research to date, regards

 

[RalphLambrecht]

Except that Howard Bond used AN glass for both the bottom and top glass plates in his enlarger, since some of the newer films have very shiny emulations, which can lead to Newton's rings. He has fairly high standards for image sharpness That said, AN glass varies in quality, and large enlargements are more likely to show up issues than small ones.

Peter

Keep in mind that Howard Bond only works in LF. At his magnifications, you would not see the AN glass texture anyway. Also, there is AN glass, and there is AN glass.

 

[RalphLambrecht]

It's counter-intuitive, but bottom AN glass, at least Durst AN glass in a condenser enlarger, will have no visible effect an any enlargement and is, in my experience a necessity for TMX. As I said before, this is something I extensively tested.

For 35mm and even MF, are you not better of leaving the bottom glass out altogether?

 

[Martin Aislabie]

quote
If you live in a climate where you're likely to have Newtons Rings - then you don't have much choice - either get some AN Glass or give up printing for those months when you are likely to encounter the problem.

What is a climate likely to induce newton rings please? I have not read this in my research to date, regards

Cool and damp/wet ambient conditions

The UK and Ireland are great places to get Newtons Rings, particularly in the Winter months

If you don't live in such Climatic conditions (a cool temperate ambient close to an ocean with predominantly on-shore winds that have travelled extensively over water) then you would be understandably (and luckily) unaware of the problem

I would presume Norway, Seattle and Vancouver would be similarly affected.

Martin

 

[RalphLambrecht]

Cool and damp/wet ambient conditions

The UK and Ireland are great places to get Newtons Rings, particularly in the Winter months

If you don't live in such Climatic conditions (a cool temperate ambient close to an ocean with predominantly on-shore winds that have travelled extensively over water) then you would be understandably (and luckily) unaware of the problem

I would presume Norway, Seattle and Vancouver would be similarly affected.

Martin

I thought it was the other way around. Newton rings form in too dry conditions and a humidifier actually helps. Have I gotten this wrong?

Dry would explain the winter months!

 

[Peter De Smidt]

For 35mm and even MF, are you not better of leaving the bottom glass out altogether?

I agree.

 

[BetterSense]

Why glass in the first place, with smaller formats? There seems to be plenty of dof on the enlarger at f/8 or so with smaller formats, and 4x5 seems to stay perfectly flat under its own stiffness. Are you all making big prints that necessitate large apertures or glass to prevent the negative from warping?

 

[RalphLambrecht]

Why glass in the first place, with smaller formats? There seems to be plenty of dof on the enlarger at f/8 or so with smaller formats, and 4x5 seems to stay perfectly flat under its own stiffness. Are you all making big prints that necessitate large apertures or glass to prevent the negative from warping?

A truly sharp print only comes from a negative that is sandwiched between glass. Depth of focus is not enough to cover negative curl, sagging and heat popping sufficiently. This is most important for smaller formats. For example, a 35mm negative setup to make an 8x10 print at f/8 has a DoF of just 0.4 mm!

 

[BetterSense]

Why is it that I can see sharp grain, then? If I can see sharp grain all across the print, then how could it be any sharper? I'm just wondering. None of my negative carriers has any glass, and the commonly available negative carriers one finds on ebay for say the beseler 23C are all glassless. Is it possible to retrofit a negative carrier to be glass-type?

 

[Bob-D659]

Depending on the neg carrier, yes it is possible to retrofit it. A 1/8" thick aluminum one can have a recess milled out to use AN and regular glass from a GEPE 6x6 slide mount. Neg warping can depend on the image and the size of the enlarger bulb.

I've got a set of 35mm negs of a narrow plume type waterfall shot in bright sunlight, they bow downwards in a couple of seconds in a single an glass carrier in a 4x5 durst enlarger with a 250 watt colour head with a 1/4" thick heat absorbing glass, but are fine in a similar carrier in a 150 watt condenser enlarger.

 

[Peter De Smidt]

Why is it that I can see sharp grain, then? If I can see sharp grain all across the print, then how could it be any sharper?

Don't worry about it, then.

When I started, I used a fairly low watt enlarger, a Philips PCS2000. I used glassless negative carriers. When I replaced the Philips with a big De Vere, I found that the added heat caused the negative to bow up with glassless carriers. So I do what Ralph suggested. I use AN glass on top of the neg, and a glassless insert on the bottom, at least with roll film. With 4x5, I use a full glass carrier.

 

[Chazzy]

A truly sharp print only comes from a negative that is sandwiched between glass. Depth of focus is not enough to cover negative curl, sagging and heat popping sufficiently. This is most important for smaller formats. For example, a 35mm negative setup to make an 8x10 print at f/8 has a DoF of just 0.4 mm!

You're the expert, and I'm willing to take your word for it, but it doesn't make sense to me. Since the glassless carriers for larger formats necessarily have larger holes in them, it would seem that the larger the hole, the greater the opportunity for sagging to occur. Beseler seems to acknowledge this by producing the Negaflat carrier for 4x5 sheet film, and I have noticed that at least one other company has a carrier which tries to stretch sheet film negatives.