Stop down to 2.2 perhaps? That works on my Canon 50mm / 1.8
What you might be able to do, in photoshop. Create a duplicate layer. Add a layer mask, paint it all black. On the data layer use a high pass filter, set the pixels to ~10. Then set the blending mode to soft light.
Not 'paint' in edges and details using a white brush on the layer mask.
Seems a lot of hassle, if you can stop down to 2.2 or higher. You might also need to consider whether any 'test images' were properly focused with this lens, the depth of field won't be large....
There used to be a site which showed side-by-side comparisons of lenses, at any focal lenght (well, not important for a prime), and at any f-stop. Can't remember the name though, it was a white test sheet.