The rare Mamiya Sekor E 3.5-4.3/35-105mm zoom was one of the last lenses added to the Sekro E/EF lineup (along with the Sekor E 4/80-200 tele zoom). This lens has a SN 10100 - probably the 100st lens produced. While size, weight and lens speed would suggest that it is a simple clone of the Tamron 3.5-4.3/35-105mm, it is not: Not only does the Mamiya's number of lenses and elements not fit the Tokina's, but also the reflections on the glass surfaces are completely different. The Osawa 3.5-4.5/35-105mm must be a different beast as well, since it is a [13/11] computation while the Mamyia E is [15/13]. It seems that the Sekor E 35-105mm was a genuine Mamiya lens which - along with the pretty rare Sekor "new" E 4/80-200mm zoom - would have played a major role in the Mamiya lineup ... if Mamiya would have continued its 35mm SLR business!