Understanding Synch and non-synch modes



SDM 1.83 and later have additional modes indicated in the screen header.
They are STEREO, S_FAST, C_FAST, BURST, SPORTS, T_FAST and T_SYNC.
Without SDM, switching your camera to playback mode and plugging its USB cable into the computer results in a programme (such as 'WIA-Loader') starting-up so that you can transfer your images to the PC.
That is because the camera has detected +5V on its USB V+ pin.
When running SDM, we will be applying voltage to that same USB pin using a switch or some other device (such as a radio control receiver) so we have to prevent the camera going into automatic download mode.
We do that by checking the option 'Disable USB Download'.
(USB upload is probably a more accurate description and used elsewhere in this documentation).

In 'STEREO' shooting mode, 'Synch' is enabled and the single-shot shooting pauses until switch-release is detected.
This is the default mode of SDM.

In 'S_FAST' mode, the single-shot photo is taken as soon as a USB voltage is detected, it does not wait for 'switch release'.
This is a non-synchronised mode (or at least, not precision synch). This is used for general photography with a single camera in applications such as digiscoping, aerial photography or kite aerial photography.
Enable this mode by setting 'focus_mode' in Bracketing menu to any value other than OFF.
(this is a little 'trick' as the focus-mode settings normally apply to continuous shooting).

'C_FAST' mode is also an unsynchronised, fast-response mode when the camera is set to continuous-shooting .
Enable Tv or focus bracketing in the Bracketing/Overrides menu.

'T_FAST' is similar to 'C_FAST' but with the camera set to custom-timer shooting.

'BURST' mode allows unlimited image-capture to be start/stopped with the remote switch.
It is an unsynchronised mode.
Tv and focus bracketing should be OFF and bracket type set to any numeric value (not darker, lighter, alternate).

'SPORTS' mode is a synchronised, fast-action mode.
Tv and focus bracketing should be OFF and bracket type set to darker, lighter or alternate (not to a numeric value).

'T_SYNC' is a synchronised bracketing mode when the camera is set to custom timer.
When creating image-pairs for HDR, it ensures that each pair is synchronised (unlike with T_FAST).
Custom-timer synch mode should be set in the Stereo menu.