I have already compared the bokeh of the lenses, and while they are both completely adequate, is is probably true that the Leica Lumix 45mm has more smooth bokeh.
So I decided to compare the sharpness as well. For this study, I took a picture of a woolen scarf with some texture using both lenses. Here are the whole pictures, scaled down and sharpened a bit. Click for larger images.
|PL45mm, f/2.8||ZD50mm, f/2.8|
|PL45mm, f/5.6||ZD50mm, f/5.6|
I focused on the centre of the image. This was done manually for both lenses.
These images are not very well suited for judging the sharpness, though. We need to study some closeups of parts of the image. Here is the centre of the images, shown in 100% view, meaning that each pixel off the sensor becomes one pixel on the image. These images were not sharpened. Click for larger images.
Comparing the f/2.8 images might pose some problems. The lenses could be focused slightly differently. With the narrow depth of field at this aperture setting, this could lead to areas being out of focus in different ways. However, looking at the areas that are in focus, I think we can see that the contrast is a bit higher in the Panasonic Lumix 45mm image.
For the f/5.6 image, all of the cropped images should pretty much be in focus, with the wider depth of field. Again, I think it looks like the sharpness and contrast is a bit higher in the Panasonic Lumix 45mm image. But people might judge these images subjectively in different ways.
I think it looks like the Panasonic Lumix 45mm macro is slightly more sharp in this example. We should keep in mind that the Panasonic Lumix 45mm is more of a dedicated macro lens than the Olympus 50mm. After all, the PL45 has got higher maximum magnification. Also the Olympus 50mm has got a larger aperture, suggesting that it is intended to be used as a portrait lens as well. Hence, it could be that the Olympus 50mm is optimized for focus somewhat further away than the Panasonic Lumix 45mm is.
It should be noted, however, that in this example, both lenses are producing images that are sharp enough for most conceivable uses. Judging their relative sharpness in this case is very close to nitpicking.
In addition to this test, I have also studied the sharpness of the lenses at a longer focus distance.