I am sure this is probably not a new subject, so please feel free to redirect me to any old threads.
I am new to the Inon Z240 strobe (type 4). Started diving w/ it and looking for tips.
I set my Nikon to Flash TTL. On a few dives I connected it with optical (& pop up the Nikon flash) and on a few others I connected it with S&S electronic sync cord. Regardless what connection method, I found every switch on the Inon, I can fire. Sttl, stttl-low, Auto, Manual, Full, everyone, it fire. On every switch (may be not Full), I can dial the EV and get fine adjustment. So while that sounds good, it looks like I have no 'sure exposure' in ttl, isn't it ? If I am shooting TTL-low on macro and I can adjust the EV from max to lowest to get the right exposure, then to me it's not TTL anymore ?!
In the last trip, I was shooting 60mm w/ both Z240 situated to the left & right of the port about 6 inches away from the port, connected electornically, I set the Inon on ttl-low with the fine EV dial down to 11. That seems to generate the least amount of output if I set it at TTL, I got over expose result.
Am I mis-using the product ? How do you typically use yours ?
I am using about the same configuration as yours: D90 with Hugyfot housing with two Z240 type 3 connected using sea&sea sync cords.
For correct use in TTL mode it does make a difference selecting STTL or STTL-LOW. (Using TTL with electical connection I am not able to "tune"the strobes output! Of cause make shure to supress the pre-flashes!
But while using this set I am facing a problem with the use of TTL. Normally I use manual exposre setting at the D90 with 1/200 shutter speed, stobes in TTL mode and exposure tuned with +/- control at the camera. In theory TTL should garantee correct exposure independant of the chosen aperture. But when I increase apperture setting (from 1/22 --> 1/2.8) each aperture step my exposure will be little lighter! It seems that the strobes don't get correct information from my camera. With the use of eg. -3EV exposure correction (with the +/- button at the D90) I can still get nice exposures at 1/5.6! My strobes can generate low enough output power...
Maybe you are facing the same problem here.