Thus, in sync mode, there is nowhere to put the half-press and it is sacrificed to allow the two necessary action for sync.
I hadn't thought about that - useful information. Does this mean that chdk overrides are still applied but autofocus loses any meaning ?
Attached is a spreadsheet with 3 possible timings for two stage capture on two separate groups of cams (using A1200 timings as a potential baseline here
http://chdk.setepontos.com/index.php?topic=8312.msg107601#msg107601A:
(i) Synch hook missing (ii) Onespush (iii) Synch Enabled. Manual Focus / Manual Mode, no chdk overrides - long canon shutter period. Two stage flash capture requiring total of 64ms blackroom conditions.
B:
(i) Synch hook missing (ii) Onespush (iii) Synch Enabled. Manual Focus / Manual Mode, no chdk overrides - canon shutter period, say 10ms. Continuous light for first group cature. This then moderated to allow projector "noise" pattern through. Total period: first shutter/sensor open -> last shutter/sensor closed = 75ms
C:
(i) Synch hook fixed (ii) Onespush (iii) Synch Enabled. Manual Focus / Manual Mode, no chdk overrides - canon shutter period, say 10ms. Continuous light for first group cature. This then moderated to allow projector "noise" pattern through. Total period: first shutter/sensor open -> last shutter/sensor closed = 69ms
However, it may be that precision synch could provide far superior results (and the outliers be ignored perhaps) - it would therefore still be appreciated if the synch hook could be enabled for the sx150is at some stage (and whatever else is/(may be) needed to enable precision synch).