I received my Sony A6300 last week after urgently ordering due to the arrival of a nephew. (I sold most of my Canon gear). Doing a small baby shoot for my sister, my new nephew I used a mix of remote Yongnuo and Nikon Speedlites set to SU4/optical trigger and manual output.
With the A6300 on manual, 1/160, ISO100 and f1.8, using the inbuilt flash to trigger the remotes I found the flash, at 1/1 power, were barely lighting the set when it should have been overexposed. However, moving to f5.6 / 8 etc it was woefully underexposed. No change of setting seemed to fix it.
Using a Canon 580EX II mounted to the A6300 at 1/64 it all worked perfectly with no exposure problems and we reduced the main flash down to 1/8 with the camera at f8 / 1/160, ISO100.
I'd be grateful if any knows why the inbuilt flash as a trigger causes the exposure problem when the camera was on full manual? Some AE override? Or a flash sync problem not triggering the remote flash during actual exposure?
Steve