Inon S2000 strobe

This tiny underwater strobe from Inon is perfect for compact cameras or as a second or third slave strobe for SLRs. However the English translation manual is near impossible to understand as are the labels on the strobe controls.

It's important to understand that this is a slave strobe that fires whenever it detects another flash. You cannot change this behavior, so if your camera fires a pre-flash and exposure flash for each shot, the Inon will also fire a pre-flash and exposure flash.

STTL mode

Turn the switch to STTL and the Dial to B.

STTL mode gives Auto flash exposure by copying the duration of the camera flash.

If the result is too dark turn the dial towards A for 3 clicks of "plus" adjustment.

If the result is too light turn the dial towards C for 5 clicks of "minus" adjustment.

I rarely use STTL mode preferring to work fully manual.


Found on the dial at 9 o'clock or -5.5. Ignore it. This is only there to confuse you. TTL relates to film cameras. Digital cameras don't use TTL for flash, they use STTL. With TTL the exposure is worked out while the shutter is open and the flash is quenched when enough light has been delivered, requiring only one flash. With STTL the exposure is worked out by doing a pre-flash. Rotating the dial to TTL allows the S2000 to sync with a strobe connected to a film camera in TTL mode (I think).

Manual Mode

Turn the switch to M and the Dial to Full.

From there you can reduce the power by turning the dial anti-clockwise. There are 11 steps from Full power around to mimimum power of -5.5.

In Manual mode the flash fires when it sees the camera flash but delivers whatever power you have selected on the dial.

If your camera fires 2 flashes for each shot then Full and -0.5 power it will not work because the S2000 cannot recharge from the pre-flash in time for the exposure flash.

Full and -0.5 can be used when the camera or strobe used to trigger the S2000 only produces one flash.


The S2000 is supplied with this little magnet and retaining screw. The magnet is used to turn off the ACC (Advanced Cancel Circuit) when in Manual mode. ACC is always off in STTL mode.

All the ACC does is save the camera battery life by making the S2000 give a brighter first flash. This fools the camera into giving a darker second flash, with the S2000 giving whatever power flash you have selected.

The ACC is only useful for compact cameras that always give 2 flashes. For these cameras leave the magnet out if you want to use the S2000 in Manual mode as well as STTL.

For all other cameras leave the magnet in to cancel the ACC. There is no way to make the S2000 ignore the pre-flash.


The S2000 has a very sensitive sensor which will work without a fibre optic sync cord in some configurations, they call this "wireless". Inon have included various mirrors and stickers to assist setting up for wireless flash operation.

On shallow sunny dives the strobe may fire continually if the sensor is uncovered. Fit the sensor cover/mirror or a fibre optic sync cord to prevent this.

Inon S2000 photos