I just picked up a lens marked only "Darlot Opticien". It appears to be a wide angle design. Focal length is about 10" or slightly less. Coverage is substantial; from the ground glass image this lens looks very promising on 7x17. There are three levers equidistant around the barrel which operate swing-in stops. That gives four stop options including wide open. Don't know what the stops are (and haven't measured the apertures yet). Lens appears to be two groups, possibly symmetrical, but don't know. Each group shows two bright reflections and one dimmer reflection.
Can anyone offer any insights into this lens, it's design, attributes or history?