How many times have you seen "small cleaning mark on lens, does not affect image quality" in ads for used cameras? Is it true? What about severe defects, like, say, "a loose spiral spring, some odd hardened liquid bubbles, dust, and a unidentified German insect in the lens"? Jurgen Kreckel, who repairs and rebuilds vintage medium format folding cameras, took such a lens—a 50/1.4 Planar—to Dresden and found out.
The results are nothing short of shocking.