Patent ID: 8000028

Claim:
A lens barrel comprising: a first cylinder provided with a first cylinder side helicoid on a first face; and a second cylinder provided with a second cylinder side helicoid on a second face facing the first face; wherein the first cylinder side helicoid has a first lead formed at a first region, and a second lead, smaller than the first lead, formed at a second region, and a number of the second leads of the first cylinder side helicoid is smaller than a number of the first leads of the first cylinder side helicoid, the first cylinder helicoid is configured with a first helicoid continuously formed in the first region and the second region and provided with the first lead and the second lead, and a second helicoid having only the first lead, the second cylinder side helicoid, in a state where it has been developed into a planar surface, is provided with at least two groups of flank faces including two sides parallel to each other, in the first region, one group of the flank faces including two parallel side of the second cylinder side helicoid is respectively guides by a flank face of the second helicoid and a flank face of the portion having the first lead of the first cylinder side helicoid, and in a transition region between the first and second regions, another group of flank faces including two parallel sides of the second cylinder side helicoid is respectively guided by a flank face of the portion having the second lead of the first helicoid, and by an end face of the second helicoid.