The large knob on the front is for winding and setting theslow speeds. The black line is not a “groove”, just a mark for setting. Each exposure requires winding this knob, and upon exposure, it “unwinds”. All the numbers etc. on the camera and lens are very small. However, the focus distance numbers are big and easy to see. Another interesting thing is that this camera has a removable take up spool and can use a true cassette to cassette film travel. PS the top button front is for the film rewind. Oh, and it has a built in extinction meter....Oh, and it has a Hot Shoe. I’ve modified a much later half case, that took care of the no strap lugs. Nice Camera. Weird to think of it as being made in 1943. Most American industry was either involved in the war effort or mostly shut down. It IS possible the entire Perfex operation was Carl and Joseph Price and Benjamin Edelman. Their output was very low , roughly 5000 per year, from 1938 to 1950. Most likely nearly every part was outsourced, with assembly and finishing done by these men. Doing the math, it would mean each man assembling five cameras per day.....entirely doable.
