Earlier versions of Capture One 7 did not work at all, or did not work well with Canon tethering in 10.7.5 and 10.8.X due to a change Apple made to their OS (see
this article about Canon tethering in 10.7.5 and 10.8).
However, those OS related problems were
mostly resolved initially
with the 7.0.2 update. The "mostly" relates to a lingering issue wherein the camera would not automatically reconnect after the connection was lost unless you restarted the software. This lingering issue was addressed in later updates and is not present in 7.1.3.
The following combination should work great:
- OSX 10.8.4
- Capture One 7.1.3 activated as Pro
- Canon 5DIII with latest official firmware
Most recent combinations should also work but above I have given you the combination which is most current and likely to give you the least problems. Since you indicate you are having problems with 7.1.2 and 10.8.4 and a 5D3 w/ ML 1.1.3 there can only be a handful of causes:
- you are not activated as pro (go to Capture One > About and see if you are instead activated as Capture One LE or DB which would not tether to a Canon at all)
- the ML 1.1.3 firmware disables or makes inoperable C1 tethering in contrast to the Canon-official firmware. Try switching back to the official firmware or borrow/beg/steal/rent a 5D3 with up-to-date official firmware.
- your USB ports (computer or camera) or USB cables are not fully working (unlikely given your indication that EOS Util works correctly, but not impossible as intermittent failures can manifest themselves in strange way vis a vis which software does or does not connect)
. Try it with a different USB port (the one closest to the power supply, if you haven't already tried that one), a shorter cable (preferably the stock cable that Canon itself provides), and unplug ANY other USB device which is connected (unless absolutely required for your setup).
- some other software is "stealing" the connection; only one software package can control the camera connection, so if e.g. EOS Util (or some other camera related app) is open then C1 will not be able to connect. Test with ALL other applications closed before connecting the camera.
By the way, your post was very well formed and represents a "good" post here - not only did you not miss any formalities you did a great job of outlining the nature of your problem and asking for help in a polite way. I hope you stick around and share both sides (the helping and the getting help as able and as needed).