MFT camera and 2nd curtain flash with v6ii
After an workshop with long time flash pictures I encountered following problem:
If I switch my MFT cameras (GH3, E-M5II, E-M1II) to second curtain, the power output of my flashes (Canon 580II, 550) is to high with exposure times longer than 1 second.
If I do a direct comparison with 1st curtain, the power output at 1/32, 1/64 or 1/128 is the same with 1/4, 1/2, 1, 2, 4 ,8 sec. When I switch to 2nd curtain, the pictures look identical with 1/4, 1/2 or 1 sec. If I then move to 2sec, it looks like the flash uses full power, independent from the selected power. the panasonic behaves like the Olys, but it looks like one stop later (at 4sec)
Is this strange behavior related to MFT cameras, the Canon flashes or he v6ii? I use the 580 profile (FW 1.006), because with the auto profile both flash types are showing some multi-flash behavior, like a pre flash from TTL. This is visible with 1st and 2nd curtain. When I do 2nd curtain longtime with the auto profile, it generates a pre flash before exposure and the exposure flash at the end of the second. Thats not the case with the fixed 580 profile.