(C) KEN ROCKWELL

Nikon's premium CRC (automatic close-range correction) lenses have at least two separate sets of elements moving in relation to each other as one focuses. This is done so that the lens retains optimum performance as the distance changes. These tend to rattle more because there is more stuff moving around. The ultra-wides and fast wides were first ones to have this feature starting in 1969. All the micro/macro lenses since 1977 have had this. Nikon uses extra sets of helicoids to control the different groups of elements.

The 105 AF is more amazing still. Not only does it have CRC, but now the internal elements are all moving around on cams as you focus! Some elements move non-linearly while focusing from one end to the other. Cams allow Nikon continuous control of element position, and not simply linear control as a helicoid does. These cams will rattle a lot more then helicoids, and the 105 AF Micro has several cams:

A.) Look in the back of the lens and look inside as you focus manually from infinity to 1:1. The rear element stays put, while:
1:) an inner element moves closer and then further away, and
2.) The diaphragm moves continuously further away

B.) look into the front of the lens as you focus from infinity to 1:1. You'll see:
1.) The filter ring move out,
2.) the front element move towards the filter ring, and
3.) The diaphragm move a little bit closer to the front element.

In other words, there is a whole lot going on inside this lens to assure top quality at all distances, and the sound of stuff rattling is all the separate free groups of elements rattling. Cams have more play than helicoids, and allow more freedom to design the lens for optimal performance at all distances. I'm very impressed at the advanced lens design Nikon did and didn't even brag about. The filter ring on mine has visible play, but less then 1mm. This is typical for AF lenses.

STATUS : LIKE NEW MINUS - white package