I noted this to myself when Nikon first posted their Road Map for Z lenses: it won't take a lot to fill in some DX (APS-C) lens gaps.
Let's look at the Z Lens Road Map, but restate all lenses as to what their effective focal length would be on DX. Let's start with the primes:
- 30mm f/1.8
- 36mm f/1.8
- 53mm f/1.8
- 87mm f/0.95
- 128mm f/1.8
As with the DSLR line, the missing element here is true wide angle. Add a 12mm f/1.8 DX and 16mm f/1.8 DX and you have a fairly nice prime set. True, size would be a bit of an issue compared to what Fujifilm is doing, but optical quality would not. Indeed, optical quality of the existing Z lenses in the DX frame is superb, totally state-of-the-art. So just fill in two wide mirrorless DX primes and you have an arguably solid lineup. Backfill with smaller f/2.8 primes over time and you can get the size/weight benefit back.
For the zooms:
- 21-36mm f/2.8
- 21-45mm f/4
- 36-105mm f/2.8
- 36-105mm f/4
- 105-300mm f/2.8
The only thing many people would complain about here is not having a mid-range zoom option that starts at 24mm (FX equivalent), and maybe not having a superzoom option. Again, two lenses could fill that in: 16-70mm f/2.8-4 DX, and 18-200mm f/3.5-5.6 DX.
So: four new lenses and Z DX has a reasonable base lens set by the end of 2020. And don't forget that we've got the FTZ adapter, so all those AF-P DX zooms come right over from day one, too, as well as the handful of other DX lenses that are still current.
This isn't a perfectly optimal solution, obviously, but it would get the job done for the time being.
The real question is this: would Z DX be consumer-oriented or prosumer-oriented (or both)? If it's totally consumer-oriented, then the current AF-P DX lenses—10-20mm, 18-55mm, 70-300mm—would need redesign for the Z mount, along with a superzoom (18-200mm minimum). If it's prosumer-oriented, then Z5—Z replacement for the D500—users would really want a dedicated DX lens set that's optimized (e.g. 10-20mm f/4 DX, 16-50mm f/4, 50-135mm f/4 as the base, with f/2.8 options down the pike, plus some DX-only primes).
This, of course, is just idle speculation on my part. No one yet knows what Nikon has decided to do with DX. I'm pretty sure that Nikon changed its mind on that themselves some time mid last year (e.g. by fall 2017).
