The X-24 Auto is a small and compact, thyristor-controlled electronic system strobe for the Konica SLR system with a guide number of 24 (metric) / 80 (feet) at ISO 100/21° and a colour temperature of 5,500 K.
For power supply, the X-24 Auto needs four AA batteries, the battery compartment is in the back side of the flash. The sliding battery compartment cover is removable. This battery compartment lid is the typical weak spot of the X-24 Auto. The noses that keep the cover in place are very fragile and break off easily. When this happens, the battery compartment is not staying closed, the power supply fails and the flash cannot be used properly – this is the case with most X-24 Auto on the market, unfortunately. This part is a real nuisance.
The X-24 Auto cannot be tilted and the earlier version with the flat foot cannot be swiveled, neither. The flash, seen from behind, is going down to the level of the flash shoe on the left side. So it must be taken off the camera for rewinding a film, as the flash is obstructing the rewind crank.
Later versions of the X-24 Auto flash were equipped with a higher, turnable foot – allowing for clockwise rotation of 90° – so that the flash can be turned out of the way for rewinding film. This setting can be used for taking photos only with some limitations, as the entire flash – including the thyristor – turns sidewards, so that the sensor does not point in the direction of the subject any more. Therefore, indirect flash can only be used in manual mode.
The X-24 Auto is fired only by the hot-shoe contact and has no separate socket for a PC synch cable. On the back, beside the the on/off switch, it has a test fire button which also serves as a flash ready indicator and is lit when the flash is ready for exposure.
On the top of the flash, the switch for different flash modes (manual / automatic aperture 11 / automtic aperture 5.6) is located. Beside this switch is a diagram showing the distances that can properly be illuminated with different film speeds (ISO 100/21° and ISO 400/27°) for each of the two automatic modes. On later versions, this diagram shows also the possible distances with the wide adapter mounted, marked with a W, and the distances in metres and feet. The early version has a metric scale only and lacks the W markings for the wide adapter.
The X-24 Auto was introduced together with the FS-1, which was the first Konica SLR body to provide dedicated flash functionality. It was sold until the SLR line was abandoned altogether and therefore can be found easily. The X-24 Auto was delivered in a black pseudo-leather bag.
Automatic flash exposure
With the electronic bodies FS-1, FC-1, FP-1, and FT-1, the X-24 Auto system flash controls the camera's electronics by two additional contacts in the flash shoe. When the flash is in automatic mode, the camera automatically sets to a shutter speed of 1/100 s and to an aperture preset on the flash, if the aperture ring on the mounted lens is in AE position. On the flash, two aperture values can be set: 5.6 (green) or 11 (red). 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. The range of usable film speeds for automatic modes reaches from ISO 25/18° to ISO 400/27°.
For demanding flash photography, the Konica flash 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.
On the X-24 Auto, the automatic function can be switched off and the flash can be used in completely manual mode.
The automatic exposure controlled by the thyristor can also be used on manual bodies that do not offer the dedicated flash functions of the electronic bodies. Shutter speed and matching aperture must be set manually on the camera in this case. Because the X-24 Auto does not know the speed of the film in use, the film speed has also to be considered when selecting the aperture. The automatic exposure control of the flash is assuming an ISO 400/27° film. With an ISO 100/21° film and the green setting on the flash (aperture 5.6), you would have to set an aperture of 2.8 on the lens.
Use with wide angle lenses
The lighting angle of the X-24 Auto flash is wide enough to properly illuminate the angle of view of a 35 mm lens. If the flash is to be used with a 28 mm lens, the wide adapter should be used, which was available as an accessory. This wide adapter diminishes the brightness of the flash and reduces the guide number to about 17 (metric) / 55 (feet) at ISO 100/21°. This is the equivalent of one f-stop, so in manual mode just open the aperture one full stop compared to the setting without wide adapter.