Searching for alternate lenses for doing IR with my modified Z5 & Z6 cameras, I retrieved the old Zoom-Nikkor 35-70mm f/3.5 lenses from their retreat. The oldest model has 72mm filter, low contrast, only focus to 1m, and is very sharp. The newer model has 62mm filter, slightly higher contrast but a tad less sharp than its predecessor, and focusses to 0.6m and has a "macro" feature as well. These old zooms are also distinguished by low amounts of geometric distortion and good control of chromatic aberrations.
Both delivered crisp IR images without any trace of hot spots, thus I need to avail myself of these for upcoming forays into the "wild". I ended up opting for the 35-70 #62mm thread as this model was easier to fit with a lens shade (using the HK-15). The 850 filters from UVIR Optics have shallow front threads and one cannot add shades directly to them.
A test shot to verify the lens indeed has no hot spot. I have tested the lenses from wide open to f/22 and there is nothing to be seen anywhere.
