Hoya started making lenses in the mid 1970s and produced a range of Prime , telephoto and zoom lenses. The smallest of these seemed to be a 24mm f1:2.8 prime, wide angle lens.
The range went through 28mm and 35mm wide angle lenses, to 135, 200, 300 and 400mm telephotos and on to the zoom range. The smallest zoom appears to have been a 25-42mm f1:3.5 device, the largest a 100-300 f1:5 item, the one I first bought.
The lenses were made to fit all the popular mounts of the time, including the ever popular M42 screw mount which is still favoured today for it's use with an adapter to fit most modern bodies.
By the mid 80s hoya stopped production of lenses, the reason seeming to be a refusal to compromise quality for cost, and concentrated on filters and optical glass. The company went from strength to strength.
One source states that the lenses went on being produced and sold under the Tokina name. This is only a rumour though and it seems more likely that the lenses were sold under the MITSUKI name.
The lenses tend to be heavier than, say a Soligor equivalent, this seems to be a result of the high quality glass used, which results in a fast sharp lens. When supplied they came in a carrying case with end caps and instruction leaflet, the packaging was well presented and thought out. To my knowledge all the various lenses made were manual focus, autofocus still being a dream when production ceased, if you know otherwise or can provide any information to update this site please let me know.