Olympus E-M1 Journal: #10: Wide open 12-40 v 14-54

In journal entry #7 I wrote about my comparison of the 12-40 and 14-54 when shooting a brick wall.  Obviously not a real world comparison, but I do feel comfortable concluding that at F4 through F8 these lenses are (essentially) equally sharp, both in the center of the frame and in the corners.

I did not test the lenses "wide open".  So, today I went back to the brick wall to take a few more pictures. I suspected that I would see a difference when shooting wide open.  For the new 12-40 that would be F2.8.  For the old 14-54 that would be F2.8 to F3.5.

On older lenses it is often necessary to stop down a stop or two to get maximum sharpness.  But we are finding on these new Olympus lenses that they are at the sharpest right out of the chute at maximum aperture.

Well, that is exactly what happened.  I compared lenses at 14, 18, 25 and 35mm, all at maximum aperture.  On the 12-40 that was F2.8, and on the 14-54 that was F2.8, F2.8, F2.9 and F3.1 for those four focal lengths.

In all cases the 12-40 was noticeably sharper both in the center and at the edges. I won't show all 8 images but the results at 35mm (F2.8 for the 12-40 and F3.1 for the 14-54) are illustrative.

The overall scene at 35mm

To keep it simple, I am showing below 100% crops from the center of focus, and just two corners, the upper right and the lower left.  (The other two corners gave the same results.) What you are viewing are screenshots from Lightroom 5.

In the comparison screenshots below, the 12-40 is on the left and the 14-54 is on the right.  I used the X:Y comparison tool in Lightroom 5.

Center Focusing Point.
Click to enlarge this screenshot.
12-40 on left is sharper than 14-54.

Upper right corner.
Click to enlarge this screenshot.
12-40 on left is much sharper than 14-54

Lower left corner.
Click to enlarge this screenshot.
12-40 on left is much sharper than 14-54