Nikon 20mm f/2.8 focusing issue?

[Steve_Pfost]

I just picked up a 20mm f/2.8 af-d and after receiving it realized that the front element, or lens group?, moves, spins, with focusing. No other lens that I own focuses in this way (that I know of) I was curious if anyone with experience with this lens may be able to tell me if this is broken or normal? It seems as though it may be normal but I am unsure. Otherwise, the lens is in pristine condition, looks like it was never used. I attached a video of the lens hopefully that can clarify my question. It may be hard to see but if you look at any of the small dust specks on the front element you can see they move along with (I guess) that group.

 

[yanchep_mike]

Checked with the one I have, and nothing is rotating just moves in or out about 1/8 of an inch.
mike

 

[Steve_Pfost]

So this is bizzare, I've found through google, some people comment that the front element moves, some say it stays put. I called Nikon and the guy on the support line said it more than likely should rotate with focus but he is having the camera lab take a look. Quite interesting.

 

[santino]

Your lens has floating elements and that might be the reason for a rotating front element. The Minolta MD 24mm 2.8 does that too (the filter thread doesn’t rotate, the front lens does).

 

[john_s]

I have that lens, and the front element(s) turn with the focus ring, although the filter ring does not rotate. Mine is in good working order, so I don't think you have a problem.

 

[john_s]

I notice at

Nikon Lens Versions and Serial Nos

there are two series of serial numbers for the 20/2.8D. Mine is in the earlier series (349nnn). Maybe the later series is different? Just a guess.

 

[Steve_Pfost]

I had a feeling that there may be a possibility Nikon may have changed somthing along the lines - mine is actually later than your 528xxx serial number. Like I said the optics are pristine as is the cosmetics of the lens. The rotating elements just threw me off.