Focus shift and LoCA in the Coastal 60/4 at 1:10

This is a continuation of testing of  the following macro lenses :

• Sony 90mm f/2.8 FE Macro
• Leica 100mm f/2.8 Apo Macro-Elmarit-R
• Zeiss 100mm f/2 Makro-Planar ZF
• Nikon 105mm f/2.8 Micro-Nikkor G VR
• and, now, the Coastal Optical 60mm f/4 UV-VIS-IR

The test starts here:

Focus shift and LoCA in the Leica-R 100/2.8 Apo Macro

A few have expressed some surprise at the performance of the Coastal 60/4 at f/4 and f/5.6, which has prompted me to rerun the tests at 1:10 (one tenth of life size) magnification.

Here are the LoCA results at f/4:

The vertical axis is MTF50, measured in cycles per picture height (cy/ph). The horizontal axis is camera position shift in cm (not mm, as was the case in the 1:2 tests). The points on the left side of the graph are with the camera farther away from the subject than the points on the right. I used a 500 um (0.5 mm) step size. The three raw channels are plotted.

The 1:2 results are here:

Focus Shift and LoCA in the Coastal 60/4 macro

There is more LoCA at 1:10 than at 1:2 magnification, but the MTF50 numbers are quite a bit higher.

Here are the 1:10 results for f/5.6, f/8, and f/11:

And here are the focus shift results:

For reference, here are the focus shift results at 1:2:

Don’t forget that the horizontal scale is different: mm in the 1:2 graph and cm in the 1:10 graph.

Two things stand out. The lens is much sharper at 1:10, and the focus shift is in the opposite direction. Is there a magnification between 1:2 and 1:10 where there is hardly any focus shift? Probably, but I’m not going to take the time to go searching for it. Did I mention that these tests are labor-intensive?