Mitutoyo 2x M Plan Apo--transverse chromatic aberration

[Chris S.]

Quite unlike other objectives in the Mitutoyo M Plan Apo series (I've also tested the 5x, 10x, 20x, 50x, and 100x), the 2x lens displays notable transverse chromatic aberration(TCA). I do not believe this to be a peculiarity of my specimen of this lens, as two other forum members have, in personal communications, expressed similar observations with their Mitutoyo 2x M Plan Apo lenses.

In the test below, TCA is, unsurprisingly, most evident in the corners of the image. Being transverse chromatic aberration, it is much easier to correct than axial chromatic aberration would be, if it were present (it is not). In this test, the TCA was removed with a single mouse click in raw conversion software (Nikon Capture NX 2).


Full image from D200 camera (APS-C sensor). The print in the test subject, the output from a laser printer, is very small (4 pt?).




Crop from lower left, without and with one-click correction. TCA is evident as blue fringe to the left of black print, and red fringe to the right of it.



The image was taken using a Mitutoyo MT-1 tube lens in conjunction with the objective.

--Chris

(edited to add a bit more explanation)

[Craig Gerard]

Chris,

Thanks for the reference image.


Craig

[Chris S.]

Those reading this thread may also want to read Enrico Savazzi's subsequent test of this objective on a stack of a three-dimensional subject here.

As another update, I had the chance to test a second specimen of this lens, and found its rendering to be essentially the same as mine. This makes five copies of this lens (two tested by me, two others described in private communication by other forum members, one tested by Enrico) that seem to exhibit similar LCA.

So far (and my use of this lens has been somewhat limited), correcting the LCA has been trivially easy if done prior to stacking. I'm hesitant to generalize this experience until more testing has been done with real-world subjects. But this ease of correction is in distinct contrast to the much greater difficulty of dealing with axial (not lateral) chromatic aberration found in some other lenses.

--Chris