This eBay listing has ended : Antique Petzval Type Brass 19th C. Enlarging Lens. Excellent Condition.
This brass lens was probably made in the late 19th Century, and is engraved 5 inch Enlarging Objective, Wm. Hume,Edinburgh. The maximum aperture is approximately F3.2. The glass is in very clean condition, with no fungus, no cloudiness or haze, and no separation, or balsam faults. The rack and pinion focusing is very smooth. There is a slot for waterhouse stops, and 2 Stops. It was probably made to cover quarter plate and CDV, and will be useable also on 5x4. If you want to print negatives made with a Petzval design lens, maybe it makes sense to use another Petzval design lens on your enlarger. It could also be used on a camera, (Speed Graphic or small Wet Plate camera for example ?). It is only 4 inches long and not heavy. As you see it also has its original retaining ring, or flange. Please feel free to ask questions before bidding.