What is taking Nikon so long to get in this game?
I want the front of that body to say NIKON and let me put my D's and G's on it.
Nikon F pros: backward compatible to some degree with Nikon lenses dating back 50+ years ago.
Nikon F con: mechanical aperture control ensures that it will NOT be a smooth transition to the mirrorless future. Everyone else has gone all-electronic AF and aperture control, so Nikon F lenses without manual aperture control can't AF or change aperture on anyone else's cameras (though there are some adapters that utilize their own aperture blades rather than the lens's, but depending on the quality of those blades, that may not be a good solution). And most Nikon F lenses no longer have manual aperture control... if it says "G" then no control.
In contrast, Canon EF lenses already work on Sony bodies, with CDAF, electronic aperture, and even spitting out correct focal length info etc. If the A7RII can make it so that Canon EF lenses can be used with PDAF and not just CDAF, then that's tectonic. I can see a lot of Canon DSLR shooters moving to Sony if so.
Rant about Nikon...
I left Nikon a few years ago because it was clear to me their management was steering the Nikon ship into an iceberg. They treated their DX users like crap, especially in lens selection; at one point Nikon rep literally told DX users to buy FX cameras. No D300S successor either.
And because Nikon was too scared to cannibalize DSLR sales, Nikon issued an undersized CX sensor which does have its good points but quickly got a lot of unwelcome company (RX100 and RX10 series, FZ1000, G7 X, Ricoh GR, Samsung NX-Mini, etc.), and soon there will be folded-optics smartphone cameras that will make it even harder for 1" sensors and smaller to compete.
That does not mean Nikon is going bankrupt soon or anything, but I just got sick of waiting on them. At least with Canon EF lenses you can adapt them to Sony and Canon mirrorless cameras already, though they lose AF speed in the process.
Same here. I'm running very low on patience. After dragging my d600 and 16-35 up a mountain last weekend, I really want a lighter kit.
I'm this close to moving over to Sony...
Have you considered a pocket rocket like the RX100 series? They are getting quite good for everything but those rare situations where you MUST have a big sensor (astrophotography, sports telephoto, etc.). For daylight shots in the mountains it's dynamite.
And even if you're into astro or want wider-than-24mm (FX equivalent) so that the RX100 is ruled out, my Sony a6000 + Samyang 12mm f/2.0 lens is TINY compared to DSLR setups. The Sony 10-18/4 is also tiny compared to DSLR equivalents. If you want bigger then try an A7 + Sony 28mm f/2.0 lens or Sony 16-35 lens. All Sony interchangeable-lens mirrorless use the exact same batteries and can charge via microUSB cable, too.
I don't believe the full frame lenses and cameras from Sony are any lighter than Nikon's. The lenses definitely aren't. Pure physics determines the size of lenses for the most part. I'd say a mountain is the perfect time for a DSLR since you'll always have the camera out and around your neck/shoulder. It's when you're in busy/crowded areas that a smaller camera is really useful, or when you just want to have the camera always on you or in a bag for just in case moments.
Actually, that's not exactly true. For short focal lengths it's way easier to make a small and light short focal length lens. Only at longer focal lengths do DSLR and mirrorless lens sizes merge.
Also, about mountains... for many people, you really feel every pound when you backpack at high altitudes. That's why I usually use a RX100 when backpacking... for daytime shots it's all I need. I do wish it did better for stars, but for that I can use my a6000 + 12/2 which is super lightweight compared to anything on the DSLR size.