I inherited an IIS Retina, which is the most common fixed lens variant of the IIIS. I have not been able to find a manual for him, although the IIIS manual is fine for almost everything.
What that manual does not let's say it's the lens filter thread, and I want / need a yellow filter to make it a bit more habitable on bright days. The lens is made by Schneider-Kreuznach and describes itself as Retina-Xenar 45mm f / 2.8 and is in a Synchro-Compur shutter. I know that the thread is a little smaller than 30.5 mm because I have a lot of 30.5 mm filters: I suspect it is 30 mm, but I would like to avoid spending money on a 30 mm filter just to find that it is something strange (I guess which is metric since the camera is German, but even that is not certain maybe).
So, does anyone definitely know what the thread is for this camera?