Need recommendations of 50mm or higher lens that is sharp across the lens - any brand

[dsiglin]

Setup is almost complete, I am waiting on LED bulb for backlight and need to design/build a permanent attachment for negative holder to slide through. In the mean time I did a quick n' dirty where I taped an old negative from my holga to semi-opaque plexiglass and put a 60w light behind. Enlarging lens was set at f16. I just propped the plexiglass against the light source and shot away. Not as refined as the final system will be but the results I got are promising. I was able to resolve to the grain. I don't remember what film I used, and the image itself is very not sharp, in typical holga fashion. Here's the "scan". Obviously downsampled so it can be uploaded onto here.