That 28mm lens, by the way, is a desirable third generation 28mm f2.8 7 element lens. This is a re-design of the earlier ML 28mm lens with a lens formula the more closely matches that of the Zeiss 28mm f2.8.
Early Model Yashica 28 f2.8 ML Lens:

Late Model Yashica 28 f2.8 ML Lens:

Zeiss Lens: