After completing the service, cleaning, repair, adjustment on the 1936 Leica IIIa, I shot a test roll to see if everything was working as it should. There are a lot of things that can be wrong on an 80 year old camera. A test roll can show if the film is advancing correctly, getting the proper space between images on the negative, shutter speeds are correct, the rangefinder and lens are in good sync so the images come out good and clear. etc…
The first test roll showed that the shutter was at the right speed but on the faster speeds, it was not adjusted correctly. The second or “closing” curtain was catching up with the first curtain part way across the film area.