I'm assembling a light-weight yet capable IR lens kit for my modified Z5. Aim is to have a kit without nasty IR hot spots or otherwise bad behaviour in IR, yet lenses should be small and not too heavy. These requirements rule out most native Z lenses as they are usually big, heavy, or poor for IR, or any combinations thereof.
So far, I came up with a "2X" kit comprising Laowa 11mm f/4.5 (rear gel filter), Viltrox 20mm f/2.8 (super light, inexpensive too), Nikkor 40mm f/2 SE (also very light-weight), and the small Nikkor 85mm f/2 Nikkor AI. If longer focal lengths are required, I can add the Voigtländer APO 180mm f/4, Nikkor 400mm f/3.5 AI (unfortunatley, my light-weight 400/4.5 Z requires 95mm expensive filters *and* exhibits hot spots for IR), and top off with the mighty Nikkor ED non-If 800mm f/8.
I tested the kit yesterday, continued this morning, and of course found quickly that none of the selected lens could give decent close-ups. The Micro-Nikkor 105mm f/2.8 AIS is bad for IR and quite heavy, but passable for IR usage set wide open. The UV-Nikkor 105mm f/4.5 behaves exemplary for IR, however, so I might relegate one of my UV-Nikkors to this kit if close-up IR work is planned.
The daffodils here were captured by the Micro-Nikkor 105/2.8 AIS. Perhaps I ought to use that lens more often?