The first version of the 35-70 f/3.5 (72mm threads) was intended as a 'pro' lens and much effort was directed towards ensuring it had constant lens 'speed' along the zooming range, high sharpness and very low geometric distortion. Unfortunately, that meant a design with a large front element and with the limited efficiency of the coatings of the time, a propensity for flare. Many find the focusing and zooming rings to be too loose and lacking of precision as well.
I always liked this lens, despite the long near distance. It certainly has its share of the "rounded" and pleasant rendition so typical for the best lenses of its time.
