I had good conversation with a guy at Fotodiox last week. They sell a cheap one and a "pro" for about $90- ($150 with a chip for focus confirmation) .

He said the cheap one was made in an ordinary machine shop where the tolerances were just not as accurate. He also said the pro used a spring to hold it on instead of a some kind of split metal thing - too be honest I haven't looked at them so i didn't understand that yet . He also said you didn't buy anything by spending $300 for a novaflex.

Anyway the Pro is made at a place that makes photo gear to serious tolerances and the metal is better. He said those would be more accurate and would last longer. The cheap ones would wear faster over time and the tolerances would get worse.

His pitch to me about going with fotodiox is that those kinds of adapters for many lens types is their primary business, its what they do.

I had previously tried the cheap fotodiox and the back focus was wrong. I tried the pro yesterday and so far it looks good though I haven't looked on a monitor yet. My test is a Nikon 80 - 200 2.8 zoom that I know should track focus from CU to wide. Any deviation in backfocus will screw that up.

So far I'm not impressed by the focus confirmation chip and the salesman warned me I wouldn't be. Its not active in Live view on the 5D and only works through optical viewfinder. Even then perhaps I don't have the hang of it yet, but seemed like it would only function kind of intermittently and was no better than my eye. If someone has better ideas about that let me know.

The other hassle is the metal piece that protrudes from some of my older Nikon wide lenses (my 24, 28, 35 & 50) . They make it hard to get the adapter on the lens and supposedly will interfere with or damage the mirror. I need to learn more about that and maybe I'll break them off as J Davis suggests on another thread her. Don't want to hobble them on a Nikon though. Any more info there is also welcome.

I need an adapter to use my Nikon lenses on my 7D. I was thinking of buying it from CameraQuest for $179. Has anyone here had some experience with this company? I was also wondering do you need an adapter to use Canon lenses on a Nikon body aswell? I couldn't find it on their site, so I was wondering.

I have the old (pre-AI) Nikkor 24mm as well. I think it's an f2.8. It has a flange that sticks out more than any of my other Nikkors, all pre-AI. I've read a post from one person who says he uses the 24 with no problem, and others who say it might hit the mirror. So I haven't tried it, although I've used the 25, 105, and 200. If anybody could confirm whether that 24 is OK or not, I'd sure like to know.

The distance between lens and sensor is bigger for nikon than it is for canon cameras (46.5mm vs. 44mm). So nikon lenses on canon cameras is no problem, the adapter puts the lens a bit further from the body. The other way around is a problem, because it would mean the canon lens has to get further into the nikon body.
There are some adapters that have an extra lens to compensate for this, but the resulting image is far from perfect.