here is a rather dull photo taken with a Mockba 4 with an industar (tessar) lens. It shows reasonable sharpness out to the edge of the 6x9 negative. Check the upper left corner. This was handheld at about 1/50th f8.

If you like, I have somewhere a comparison of this lens against a heliar type. Those were done with a tripod, so it is a good comparison.