TT 5.6 to 6.3 is only a third of a stop given the ISO and noise capabilities of these new cameras is that really a concern?
Yup, it is to me. I've noticed the difference between 5.6 lenses and 6.3 lenses on my Z6. I've found situations that 5.6 lenses will AF when 6.3 wont, (crappy gym lighting shooting volleyball). Its no big deal if the subject is static but Nikon doesn't AF in low light very well, frustratingly so with slow glass. Plus, the subject separation is better with 5.6 than 6.3. This isn't a concern with longer lenses like the 200-500f5.6 vs 150-600 f6.3. Overall, I'm concerned about the trend for Nikon's amateur level lenses. F mount 18-140 was a 5.6 lens, now its 6.3 for the Z (and 30% more expensive). F mount 28-300 was a 5.6 lens, the Z may have gained 4mm at the wide end, (24mm instead of 28mm, sadly f4 instead of f3.5) but lost 100mm at the long end and also went to 6.3 (selling for nearly a grand). They do offer some great amateur standard zooms, the 24-120 & 28-75, but (still) nothing telephoto.
To be clear, I'm sure this Tamron lens is going to be fine. Any new lens at this point should give stellar results, above what lenses of yesteryear could have done at the same aperture. I hope Tamron continues to build lenses for the Z, they've got excellent glass. I hope Sigma joins it too, competition is good! It just irks me that it was THIS lens they did it to and what that means for the future of this lens for Nikon. To me, it seems like a step backwards instead of what Nikon knows their base wants. It's no secret that their Z lens roadmap had (has) a huge gaping hole in it where either the 70-200f4S (best option) or 70-300f5.6(acceptable option) should be. The 100-400 $eem$ like a great len$ for tho$e who can afford it, but I prefer the cost, size and weight savings that lens does not offer. Hopefully this Tamron lens sets the stage to allow Nikon to release the 70-200f4S (that collapses just like the 14-30&24-70 f4S lenses). I just need Nikon to start cranking out their lens lineup a little more quickly or my need for a great volleyball/Tennis lens wont be needed anymore
