Do chromatic aberrations change with distance?

The job of the lens is to project an image of the outside world on the surface of film or digital sensor.

To do this job, light rays from the subject traverse the lens and the shape of the lens surfaces and the density of the lens alter their travel path. In other words, the lens acts a light wave guide. The focal length is a measure of the distance, lens to image plane. A 100mm lens forms an image of a far distant object 100mm downstream of the lens. However, the focal length is actually a variable depending on object distance. Nearby objects come to a focus further than 100mm d downstream.

Additionally, the color of the object also influences the lens-to-image distance. Blue comes to a focus closer to the lens while red focuses last, the other colors at in-between distances. We are talking, chromatic aberration. To correct, the optician constructs the lens using multiple glass elements, each with different power and density. This method brings the red and violet rays to a focus at nearly the same place. This color corrected lens is called an achromatic, Latin for without color error. We wish this were true but alas, some residual aberration remains.

If the lens is poorly constructed, the resulting image consists of a series of image, each a different color, juxtaposed, Because of projection distance of warmer colors is elongated, the yellow and red image are somewhat larger than the blue and violet images. What happens is, the final image is befringed with a halo or rainbow of colors. Object distance plays its part. The separation of the various images is more pronounced when the lens is working in close.

Addendum Yes subject distance impacts chromatic aberration.

To correct for chromatic aberration, two lenses are combined. The first is a converging lens made from crown glass. This lens produces images at different distances downstream from the lens. First violet comes to a focus, then the other colors based on their wavelength. Red and infrared come to focus further downstream. The second lens is a diverging lens made of flint glass. The behavior of the two are opposite as to color. This companion, called an achromatic Put together, this compound converging lens well corrected for color imaging. However, residual color errors has the effect of producing different sized images for each color.

This color error is sometimes called chromatic difference of magnification. The magnitude of this error is focal length dependent. As you image closer and closer to a subject, the back-focus distance elongated. Technically the focal length remains unchanged as you close focus. This is because focal length is defined as a measurement taken when the camera is imaging an object at infinity.

There are two different variables in play here: focusing distance and object distance. Chromatic aberration correction is with some priority employed to stop colored fringes to appear when focusing on infinity: when everything is in the "default" out-of-focus situation, colorful fringes are really undesirable. A similar reverse "default" situation is the bokeh of "infinite" objects when focusing at a finite distance. A 35mm prime with fuzzy rainbow bokeh would be undesirable in most cases. But there are lots of other combinations as well.

When the review states "Chromatic aberrations after 10 meters become significant. After 15-20 meters the picture becomes unusable." it is not clear whether the stated distance is supposed to be the object distance or the focusing distance or both (namely describing only the behavior of image elements strictly in-focus).

I believe the lens had a defect, maybe a production fault, maybe a damage from mis-handling.

As user98068 said, there are two different variables:

• object distance and
• focusing distance.

For a 35mm lens, 10m vs. 20m object distance is nearly the same, the light rays follow nearly the same path (even wide open at f/2, it's easy to have both distances within Depth of Field). So, with a given focus setting, I can hardly imagine any difference in chromatic aberration (CA) between the different object distances.

But with a poor lens design or some mechanical problems inside the lens, it can be possible that at some focus settings, the CA compensation degrades or fails. It's hard to believe that by design this happens at distance settings so close to infinity. To me, it seems much more plausible that the lens had a defect, causing some elements not to move as designed, close to the "infinity" focus setting.