Fix ths BUG can't save the pictures.

[QiangJi]

No description provided.

[kylemcdonald]

hi! can you please list your:

1. Mac OSX version
2. EDSDK version
3. Canon camera model

and @ofZach does this look similar to something you've run into before?

[ofZach]

my issue had to deal with focus failing, and getting stuck in an infinite loop attempting to take a picture. this code helped me:

#24

in the end, I wound up triggering a focus attempt then delaying then taking a photo without AF, that seemed to help alot with speed and stability.

I am still slightly worried about the threading logic, it feels like some function calls need a bit of a chance to report an error or fail gracefully that seems harder to do in the thread.

[QiangJi]

@kylemcdonald

1. I am using win8.1.
2. EDSDK version is 2.14;
3. Canon camera model is EOS1200D

My first time to use.