Issues with color and old lens.

[Swift1]

Awhile back I acquired an old Wollensak 3 1/2" f/6.8 lens for use on my 4x5 camera. I think that it is basically a Schneider Angulon 90/6.8, but I am not certain and don't know if it's coated or not.
So far I have shot 5 sheets of color film with the lens, and they all have this alternating red-green circular color shift pattern in the blue sky.
Is this to be expected with this lens?

Here is an image that shows the issue.

 

[Rob-F]

I don't believe I can make out any circular color pattern on my monitor. Is it really subtle?

 

[Swift1]

I don't believe I can make out any circular color pattern on my monitor. Is it really subtle?

Yes, I suppose it's kinda subtle. It looks like alternating magenta and green rainbows in the sky.
Once I noticed it, it really stands out to me.

 

[shimokita]

Does it happen with all film or only specific brands?

 

[Swift1]

Does it happen with all film or only specific brands?

So far I have only tried the lens with Ektar and FujiPro 160S. It's more noticeable on the FujiPro, but is on both films.
I scanned 4 sheets of FujiPro 160S today. All 4 were shot on the same morning and same conditions, but 3 were shot using the Wollensak and 1 was shot using a Caltar II-N 150/5.6. All 3 Wollensak shot have the circular color shift, but it is not present in the Caltar shot.

 

[jszokoli]

If I had to guess I would say it's the scanner, not the film or lens. There's not a single mechanism that I can think of where I lens could cause that.

Joe

 

[Swift1]

If I had to guess I would say it's the scanner, not the film or lens. There's not a single mechanism that I can think of where I lens could cause that.

Joe

I'm pretty sure it's not the scanner. I just scanned 4 frames and it shows up in the first 2, doesn't show up in the 3rd, and then shows in the 4th. The frame it doesn't show up in was from a different lens.

Could it be some sort of lateral CA? It seems very lens related to me...

 

[x-ray]

Possibly newton rings where the film is touching glass. Glass holder or platen? Circular rainbow pattern is a dead giveaway for newton rings. Nothing in the lens could cause that.

Those are actually pretty good lenses. Not much extra coverage but sharp. I have a 6-1/2 " for 8x10.

 

[Swift1]

Possibly newton rings where the film is touching glass. Glass holder or platen? Circular rainbow pattern is a dead giveaway for newton rings. Nothing in the lens could cause that.

I'm fairly certain it's not newton rings...

I looked back through some older images, and found something similar in images taken with a Lomo LC-A 120...

 

[Huss]

I don't believe I can make out any circular color pattern on my monitor. Is it really subtle?

Scroll up and down while looking at the picture. It then becomes really apparent.
Looks like a lens issue to me, especially because of the circular shape.
I've had newton rings, and it looks nothing like that.

 

[x-ray]

I'm fairly certain it's not newton rings...

I looked back through some older images, and found something similar in images taken with a Lomo LC-A 120...

Does your scanner have glass that the negative touches?

Newton rings don't occur in camera. They're interference patterns caused by the film touching the glass. Actually it's not where it touches but almost touches. The film has to be close to the wavelength of the light from actual contact with the glass. This causes light waves to cancel out each other causing interference patterns or newton wrings as they're called.

If you take your index and middle finger and put them together where they're almost touching in spots and look through them at a light source provided the spacing is correct you'll see fine black lines parallel to your fingers in that gap. This is interference patterns similar to those that cause newton rings. Light is effectively energy that acts like waves in a sink. If two waves collide 180 degrees out of phase they cancel each other out. If they meet in perfect phase it doubles the amplitude.

If you have glass in contact with film in the scanner and it's not anti newton this is your problem.

 

[x-ray]

Scroll up and down while looking at the picture. It then becomes really apparent.
Looks like a lens issue to me, especially because of the circular shape.
I've had newton rings, and it looks nothing like that.

There's no way this is a lens issue. There's nothin in a lens that can project a band like this. Newton rings an take different forms from very irregular to circular. In the lens he has there are only two cemented surfaces. Even separation wouldn't show like this. These are simple lenses, a doublet and an air spaced lens in each group.

 

[Swift1]

Does your scanner have glass that the negative touches?

The negatives don't touch any glass in the scanner.
I've dealt with newton rings before and this most definitely isn't newton rings of any sort that I am aware of.

I posted this in the Optics Theory forum because as far as I can tell, this is a sort of chromatic aberration particular to wide-angle lenses.

 

[Swift1]

Scroll up and down while looking at the picture. It then becomes really apparent.
Looks like a lens issue to me, especially because of the circular shape.
I've had newton rings, and it looks nothing like that.

I agree 🙂

 

[x-ray]

The negatives don't touch any glass in the scanner.
I've dealt with newton rings before and this most definitely isn't newton rings of any sort that I am aware of.

I posted this in the Optics Theory forum because as far as I can tell, this is a sort of chromatic aberration particular to wide-angle lenses.

I've owned the same lens, the 100 mm and 2 of the 6-1/2 inch and never seen anything like that. It's been fifty years since I had any physics but I don't see how this is possible. I've never seen an aberration of any kind cause anything like that.

You should go to the Large Format forum and ask. There are some very sharp folks over there.

 

[Jockos]

Semi-circular rainbow bands, projected by the lens. I saw something similar on a lens with bad separation. I only saw it on the GG (effect was quite strong), never wasted a sheet on it though.

Have you looked through the lens with a flashlight?

 

[johannielscom]

I've seen it on JPEG compression and it doesn't happen with all images. It is a lens related thing, but the compression algorithm brings it out.

Try scanning again and saving to a different file type, uncompressed TIFF. Then save different-sized JPEGs from it. I bet it will show up in some, but not in all.

 

[popavvakum]

In the image I can see the colour and brightness circular alteration particularly strong in the upper corners. This is simply the vignetting which is worse at small f numbers. Below this I can just barely make out a faint arc with subtle purple tinge; this looks to me like an aberration caused by some internal reflections on curved lens elements surfaces. You need to have very bright objects to get those faint reflections visible. Am I right to assume that this lens has uncoated elements?

 

[sevo]

That is not the camera or lens, nor the scanner optics. It is a colour rendering issue - somewhere some software component makes a poor decision regarding colour mapping. Blue pastels are in a area where the eye can discriminate very subtle nuances, there are not enough values in 12bpp or sometimes even 16bpp to render skies like yours in a naive linear fashion, so the software has to apply perceptive dithering or hinting to avoid banding. Tweak the scanner and postprocessing software parameters...

 

[Dwig]

That is not the camera or lens, nor the scanner optics. It is a colour rendering issue - somewhere some software component makes a poor decision regarding colour mapping. Blue pastels are in a area where the eye can discriminate very subtle nuances, there are not enough values in 12bpp or sometimes even 16bpp to render skies like yours in a naive linear fashion, so the software has to apply perceptive dithering or hinting to avoid banding. Tweak the scanner and postprocessing software parameters...

I agree that it is classic banding, but it is not so much software making a poor decision as it is a result of there being no "good" decision. This is more likely to show when scanning large format film that when scanning miniature format (e.g. 35mm).

Altering the scanning resolution might improve things and using a higher bit depth in the scan (16bpp instead of 8bpp) will help. Adding a very small amount of noise will eliminate the problem. This is particularly helpful when having to use 8bpp images (JPEGs, when printing, ...).