Make sure the lens physical switch is set to Auto Focus (AF). If the lens is in Manual Focus (MF) then you will need to focus the lens manually.
Some Canon cameras also have a Continuous AF menu. Make sure that you disable Continuous AF from the camera's menu, as shown below:
Note title Lens Manual Focus Switch
While most lenses should have the physical switch to AF (for Auto Focus), we have ran into a few cases where if the lens is set in AF then the focus changes, even though the software is set to MF. In that case, we recommend you position the lens switch to MF and try refocusing again with MF in software. If focusing from the software does not work, then focus by physically turning the lens.
Make sure the camera is set to fully manual exposure (Mode should say Manual Exposure).
- With the lens' physical switch set to AF, the software can now control the lens' focus when you set Shutter Stream in the manual focus mode. Click the AF button, in the upper right corner of the controller panel, and the button will switch to MF to indicate software manual focus mode, as shown below:
- Once the software is in Manual Focus mode, you can now control the focus using the left and right arrows. These arrows will show up if you keep the mouse over the MF button:
- Final advice would be to take a look at your AF point selection. This link might be helpful: http://digital-photography-school.com/focusing-quick-tip-single-point-af-methods/