The Varifocal Hexanon AR 35-100 mm / F2.8 is a two-touch zoom with two separate rings for focal length adjustment and focusing. It was introduced during the period of the internal linkAutoreflex T3 – when zoom lenses of this focal length range were still in their infancy. The Varifocal Hexanon AR 35-100 mm / F2.8 is a huge and very heavy lens with a huge front element. The diameter of the filter thread is 82 mm! The lens does not change its overall length when focal length is changed, but the focusing point is shifting. After every adjustment of focal length it is necessary to re-focus – hence the designation Varifocal instead of Zoom. Probably it was not possible to get the constant speed of 1:2.8 with good image quality over the focal length range without this compromise. Read more