The f series introduced built-in flash synchronisation. The firing delay was variable to cater for different types of bulb, the setting was on a dial below the shutter speed dial. The contact setting required depended on the type of flash bulb and shutter speed used, the appropriate setting could be found in a table. A further table would show the 'guide number' for the bulb and shutter speed, this was divided by the subject distance (in feet) to give the lens aperture which had to be adjusted according to the film speed. On the later IIIf Red Dial, the shutter moved across the film plane more quickly so the contact numbers for Red Dial cameras differ from Black Dials.

Copying stand BUWOO

Optical Near-Focusing Device

In use the lens is secured to the unit by its bayonet, the focusing mount of the lens is not used. An optical wedge is aligned over one of the rangefinder windows and a mask aligns in front of the view-finder window. The latter automatically adjusts for parallax and reduction in field size but in use was not very precise due to the small finder window.

Pre-war Leitz made different versions of the device:

• Nooky (1935) for the 5 cm Elmar lens. In 1939 a reproduction scale was added.
• Nooky-Hesum for the 5 cm Hektor and Summar. In 1939 a reproduction scale was added and the engraving included the 5 cm Summitar.