The X-18 Auto is a small and very compact, thyristor-controlled electronic system strobe for the Konica SLR system with a guide number of 18 (metric) / 60 (feet) at ISO 100/21°.
For power supply, the X-18 Auto needs two AA batteries, the battery compartment is in the left side of the flash, seen from behind. The sliding battery compartment cover is not removable from the flash.
The X-18 Auto can neiter be tilted nor swiveled. It is fired only by the hot-shoe contact and has no separate socket for a PC synch cable. Apart from the on/off switch, it has a test fire button, a flash ready indicator, and a diagram on the back, from which the usable flash distances for film speeds ISO 100/21° and ISO 400/27° can be read in metres and feet.
With the electronic bodies FS-1, FC-1, FP-1, and FT-1, the X-18 Auto system flash controls the camera's electronics by two additional contacts in the flash shoe. The camera automatically sets to a shutter speed of 1/100 s and to an aperture of 5.6, if the aperture ring on the mounted lens is in AE position. Exposure is controlled by a thyristor in the flash, which switches off the flash when the amount of light needed for correct exposure has hit the sensor. The film speed set on the camera is automatically communicated to the flash. After exposure, the camera automatically switches to normal AE mode until the flash is ready to fire again. Subsequently, the exposure control is once again taken over by the flash.
Different from the better equipped system flashes X-24 Auto and X-36 Auto, the automatic function cannot be switched off with the X-18 Auto, and there is only one possible aperture 5.6 for automatic mode – both the other system flashex can be set to use either aperture 5.6 or 11.
For demanding flash photography, this system is not sophisticated enough. You are better off with manual flash exposure control, as that leaves you with many more possibilities to influence the result. For correctly exposed snapshots with frontal flash on a family reunion, the Konica flash system is certainly good enough.
The X-18 Auto was a late addition to the Konica system, it was introduced contemporary to the FT-1. Therefore, it's rather rare.