What causes negative to have rainbow ring?

[Andrew Billy]

Hi all,

I have been processing C41 at home. I am very consistent with temperature. Developer at 100F, Blix at 105, Stab at room temp. After scanning in all the 120 rolls, I noticed "rainbow ring" effects on the scan. I examined the negative, but was unable to see/detect the rainbow ring on the negative (I don't have a light table, I held the negative to a light source). I am uncertain, don't know, curious, wondering, a bit frustrated as to what could have caused this "rainbow ring"? Could any one offer any ideas I would greatly appreciated!

 

[chassis]

Looks like Newton's rings. Do you scan with glass film holders? What is your scanner and film holder setup?

 

[Andrew Billy]

I use a Canon 9000F MarkII, a plastic film holder that came with the scanner. What is Newton's rings? Thank you!

 

[winger]

Probably more than you wanted to know, but - https://en.wikipedia.org/wiki/Newton's_rings

 

[Truzi]

Here is some generic info on Newton's Rings:
https://en.wikipedia.org/wiki/Newton's_rings
(ETA: Winger beat me to posting the link )

If your film is slightly bowed or curly, it may contact the scanner glass even if it's in a film holder. In your image the rings are more-or-less in the middle, which would support the "bowed" theory.

 

[Sirius Glass]

Welcome to APUG

Definitely a scanner problem. Listen to Winger.

 

[Andrew Billy]

Thank you guys so much! It was very helpful! It was exactly the bow of the film, making contact with the glass. I flipped it around, and no more Newton's Ring.

 

[pschwart]

Thank you guys so much! It was very helpful! It was exactly the bow of the film, making contact with the glass. I flipped it around, and no more Newton's Ring.

you can get some ANR (anti-Newton ring) glass and use it on the base side of the film.

 

[RalphLambrecht]

Hi all,

I have been processing C41 at home. I am very consistent with temperature. Developer at 100F, Blix at 105, Stab at room temp. After scanning in all the 120 rolls, I noticed "rainbow ring" effects on the scan. I examined the negative, but was unable to see/detect the rainbow ring on the negative (I don't have a light table, I held the negative to a light source). I am uncertain, don't know, curious, wondering, a bit frustrated as to what could have caused this "rainbow ring"? Could any one offer any ideas I would greatly appreciated!

They are Newton rings, which are created when th flat shiny side of the film comes in close contact with the fast glass surface under a bit of pressure. You need to replace that flat glass surface with something calledAN(anti Newton)glass, which is slightly frosted to prevent this phenomenon; happens in enlargers too; nothing wrong with your negative!

 

[georgegrosu]

About 30 years ago, to remove the problems with the Newton rings, we were taking out the glass from the 35mm magnifiers and using only two masks (above and below the film).
The negative was between two metal masks without glass.
Press the film was done only by the side of the board that runs on the negative.
The Newton rings did not appear anymore.
Since they've come to us and the minilabs do not use any of the classics magnifiers.

George

 

[AgX]

Newton Rings? Well, what about the developer acting psychodelic...?

 

[RalphLambrecht]

About 30 years ago, to remove the problems with the Newton rings, we were taking out the glass from the 35mm magnifiers and using only two masks (above and below the film).
The negative was between two metal masks without glass.
Press the film was done only by the side of the board that runs on the negative.
The Newton rings did not appear anymore.
Since they've come to us and the minilabs do not use any of the classics magnifiers.

George

that will definitely work but it changes the problem to risking film not being perfectly flat.AN glass is a better solution without the trade-off.

 

[georgegrosu]

Ralph W. Lambrecht, you are right, but until 1990 we had about 15 ºC in the winter în the house.
If we were working with color photos, the temperature of developer was at 31 º C.
I think you can think of what problems you had with the glasses from the negative gate.
At that time I did not work 6 x 6 cm films.
For a 35mm film I did not have problems with planarity.
In cinematography, 35 mm / 35 mm contact printers, to ensure planarity of the film, blow filtered air from the back of the printer gate.

George