QUOTE(IwanAGP @ Jan 31 2015, 11:26 PM)
All converters from lenses with larger flange distance (DSLR lenses - Nikon FX/DX, Canon EF/EF-S, Sony SAL lenses, Pentax etc etc and even film era lenses that covers 35mm format film) can be mounted on most mirrorless camera (shorter flange distance/smaller sensor size) with a converter that DOESN'T have any optics. Electronics maybe got but mostly no optics. Except some like metabones speedbooster that claims to fit full frame FOV into APS-C size sensor (no more crop factor although used on APS-C sensor) and also wider aperture... And Sony its own LA-EA2/4 that has a transluscent mirror for phase detect AF sensor to work. These have optics/mirror in it. Otherwise all the cheapo made in china converters is basically just a mount converter. No electronics, no mirror, nothing inside the converter.
Electronics are for AF/Aperture etc.
Say for Canon newer lenses without aperture ring, the aperture can only be controlled electronically. Some more expensive adaptors have this function. Some even can do AF. Not sure about Nikon ones though. But if you buy real old legacy lenses, mostly come with aperture ring one la

QUOTE(ChinWY @ Feb 1 2015, 02:50 PM)
Yes they are just to help mate the two different mounts together.. What you may find annoying is it my overshoot the infinity focus position.. You can fix it if you are really fussy by shimming.. or get a focus helicoid and pin it into a fix position.. Some people complain of lens wobble with these interface.. again can be fi very easily.. a dab of slow set epoxy and careful grinding will do the job.. If you look at some of the sony lens you will also see epoxy in the mounts too!
if your Nikon lens has separate aperture and focus control it will not be an issue.. I know my A1 type works great..
I have the autofocus adapter for Contax G - Zeiss lens.. performance is not good enough.. and it is expensive.. focusing on such prime lens need to be precision..
What I do find out is Focus Peaking should be turn off.. I find it give me false information... I turn it off in a wedding photoshoot recently and found I got better results..
QUOTE(Eiraku @ Feb 1 2015, 05:14 PM)
Quality? Like someone said before, Nikon-Nex adapters (not Speedboosters, mind you) don't have optics so besides losing some light (and some of the lenses not being optimised for digital) you don't really lose much.
Except maybe if you get one that effs up infinity.
That said, G lenses need G adapters because they don't have aperture controls on-lens. For everything else, the common Nikon-Nex adapters work fine for everything from Pre-AI to the normal AF lenses, but you'll need to MF all of them ler.
My personal fave Nikkor so far is the very old Nikkor SC 1.4/50. Not too huge (like a Nikkor 1.2/55) and not too slow. It's not the sharpest but for portraits it works nice as its a tad dreamy and the bokeh is not too harsh and not too quirky (unlike most other Nikon fifties).

Unfortunately, MF-ing it is a massive pain at f1.4 and with the adapter it's actually more on the heavy side of things, so I don't really bring it along that often coz I like to keep my walkaround kit small. Plus I don't really shoot at 50 on crop that often.
Which is a real shame as it does render very well.
Here's an old test shot though:
Nikkor SC 1.4/50 Test by
Eirakkun, on Flickr
Thanks, will give it a try!