After using the flash a few times, it inevitably stops working. I understand that the flash can only fire a certain number of times before needing a rest.
I have noticed that after the a77 reaches this point, it can only then fire the flash once every 10 seconds, even if the little 'flash charging' icon light has switched from blinking (ie flash charging) to steady (ie flash ready). Even if it indicates Flash Ready, it will not fire until about 10 seconds have elapsed since the last flash. Even waiting 3 *minutes* after the flash runs out of energy still only allows further flash use at a rate of one flash every 10 seconds. At this point, the flash is not even warm.
The manual states that the recycle time for the built in flash is 'approx 3 seconds'. In real life, even firing manual flash at 1/8 runs out of energy after 15-20 shots. In wireless flash mode, the pop up flash stalls after 15 shots exactly, every time. I reckon WL pulses are roughly equivalent to 1/8 power fill flash shots, after looking at the brightness the WL pulse contributes to an image and adding a bit more for the pre-flash control sequence.
When the flash has reached the 'stalled' state, the 'flash ready' indicator is steady, indicating ready. When you press the shutter button, the indicator starts to blink again. This lasts 10 seconds then finally you take a shot.
Now, here's why I think this is a bug.
Interestingly, if the camera reaches it's power saving time and goes to sleep, if you wake it up again after just a few seconds (eg with a half shutter button press), the flash is suddenly no longer hung and works perfectly again. I have tried this with 10s, 1m and 5m powersave modes. In every case, the flash can be used repeatedly until hung then un-hung by a brief (5seconds) of powersave mode. Until powersave has been entered, the flash is stalled, after powersave has been dismissed and the camera reawoken, the flash is normal again and can fire off another 15 shots.
Example: Shoot at 1/8 power in Drive mode Lo (3 fps). You can get about 15 or so shots at 3pfs before the flash hangs. After this, you can only shoot once every 10 seconds. Even if you leave 3 minutes before trying any shooting at all again, you can still only get one flash shot every 10 seconds. However, if the camera enters powersave mode for about 5 seconds, when you reawaken the camera, it can manage another 15 shots at 3fps before stalling again.
It seems that if a power save after 5 minutes is as effective as a powersave after just 10s, surely something odd is happening deep inside the flash control system
Can anyone else try this and see how they get on?
