The last time I tried Infra-red (IR) photography I was using a Nikon D80 and the results were not very good. Exposure times were around 30 seconds and the lenses in my kit at that time didn't play nice with IR and made all sorts of 'hot spots' in the picture. The post processing tools I had available were also not very flexible.
Fast forward a couple of years and I realised that I hadn't tried IR with the D600, current lenses and processing tools. I didn't have high expectations, but was delighted with what I found:
Nikon D600, Nikkor 18-35mm D* lens, Cokin 720nm IR filter, 3sec, f8, ISO800. Processed in Lightroom and Photoshop CC.
Notice the white dot (center top)? That's a daytime moon, mid-day with lots of sun - only with IR. So, all in all and for an unconverted, non-IR camera, the D600 does a pretty good job and the 18-35 D makes a reasonable IR lens (it even has the focus adjustment marks for IR).
Note: I have no idea how the latest 18-35mm *G* lens performs - it is totally different from the *D* being used here and has no IR markings.