Why EdsDownloadEvfImage() always return EDS_ERR_OBJECT_NOTREADY

Question

I am having a problem trying to call EdsDownloadEvfImage() from the Canon EOS SDK in order to start the live view feature. It always returns EDS_ERR_OBJECT_NOTREADY which signals that the image data set is not ready in the camera or that the image data set cannot be obtained.

code:

    if(err == EDS_ERR_OK)
{
    err = EdsDownloadEvfImage(camera, evfImage);
    int i=0;
    while(i<20 && (err == EDS_ERR_OBJECT_NOTREADY))
    {
        err = EdsDownloadEvfImage(camera, evfImage);
        i++;
        Sleep(100);
    }
}

Answer 1

Have you started the live view before calling your code?

You need to set the Evf_OutputDevice property to PC (or simply something other than Off or Camera). After setting that, it may take a little bit and then you should be able to download live view images.