Is there any meaning to this?

[Abitconfused]

Below is an image of a lens calibration target. There was no need, in my opinion, to adjust this focus as it appears spot on. What interests me is the color fringing that only appeared after the image was subjected to extreme saturation. My theory is that the point of most accurate focus is also the freest of color fringing, whatever the source.



Is this an accurate assessment of what is happening here?

[BobGilbody]

I am always confused. Humans see with their mind [ not the brain ] not their eyes. cameras and lenses don't have minds.

Not sure this would help.

[pschlute]

Is this an accurate assessment of what is happening here?

I don't know the optical reasoning behind this, but out-of-focus areas of any image are always more likely to show purple fringing/chromatic aberration than the in-focus area.

[george013]

Below is an image of a lens calibration target. There was no need, in my opinion, to adjust this focus as it appears spot on. What interests me is the color fringing that only appeared after the image was subjected to extreme saturation. My theory is that the point of most accurate focus is also the freest of color fringing, whatever the source.



Is this an accurate assessment of what is happening here?

In general lenses are at their best in their focal plane, at their best aperture. Maybe some more items. A matter of lens design.
In your example you probably used a vertical plane to focus on and a ruler guide placed at 45 degrees.
From https://en.wikipedia.org/wiki/Chromatic_aberration
.
The sensor is parallel to the lens. The size of that aberration is a metric size. The higher your pixel density, the more pixels in that size. So your D810 is very sensitive to that kind of aberration. By adding an agressive pp you make it more visible. Maybe if you flatten the ruler some more, you get more aberration of this kind.
You can also play with different apertures or different resizes or zoom levels.
Just some thoughts.

George

[Abitconfused]

Same image before saturation...

[DanK]

This is beyond my expertise, but George's post makes sense to me. CA is essentially a partial error of focusing: the various colors are not focused at the same point. This should be worse as one moves away from the focal plane. If the flaws like CA are minor, they will become more apparent as you increase saturation.

[Abitconfused]

Yes, I am considering the best way to calibrate a lens and I now believe that it is far more accurate to inspect a target image in Photoshop for color fringing than to use live view.

[Stagecoach]

Yes, I am considering the best way to calibrate a lens and I now believe that it is far more accurate to inspect a target image in Photoshop for color fringing than to use live view.

I have always been under the impression that the only place you would 'inspect'/'compare' your target test images would be on the computer monitor. Live View used only to assist with attaining the best manually focused example used for comparison against AF results if wanted.

[Abitconfused]

Oh! I had never thought of that. Thank you

[Stagecoach]

Oh! I had never thought of that. Thank you

You are welcome.

I'm going to be checking the calibration of my 70-200 2.8 and 1.4TX combination this weekend so will look at the CA colours out of curiosity to assist whilst assessing the results.

[Abitconfused]

Good deal. Please let us know what happens.

[Abitconfused]

A new image of my 18-35mm being tested at 25mm range.