problem with SDK kEdsCameraCommand_BulbStart

In a code project I'm currently developing, the following code works:

result = EdsSendCommand(camera,​kEdsCameraCommand_Take​Picture,0);

result is EDS_ERR_OK and the shutter clicks.

When I change the code (literally inline) to:

result = EdsSendCommand(camera,​kEdsCameraCommand_Bulb​Start,0);

the call fails and result is EDS_ERR_INVALID_PARAME​TER.

I've tried (successfully) locking the camera UI first, but it made no difference, the call still fails. I've tried everything with the camera in BULB mode and in MANUAL mode, no difference.

Can anyone help me? Why is this failing?

Thanks in advance.

While nobody was answering, I may have figured out the problem myself, so I thought I would document it here for others who may want to know in the future.

I suspect that the two SDK commands:

kEdsCameraCommand_Bulb​Start
kEdsCameraCommand_Bulb​End

are for cameras that consider bulb mode to be the lowest available shutter speed, and are designed to be used when the camera has been configured to that shutter speed.

For (more recent?) cameras, in which bulb mode is an entirely separate AE mode, to open and close the shutter when in bulb mode use:

kEdsCameraCommand_Pres​sShutterButton

with the two respective arguments:

kEdsCameraCommand_Shut​terButton_Completely
kEdsCameraCommand_Shut​terButton_OFF

I don't consider this a definitive answer, it's simply what worked for me (I'm testing on a 5D Mark III)