Post by Vihang Vasa, Photonics Enterprise in Mubmai, India
As with previous USB versions, USB 3.0 ports come in low-power and high-power variants providing 150 mA and 900 mA respecitively while simultaneously transmitting data at SuperSpeed rates. Additionally, there is a Battery Charging Specification (Version 1.2 – December 2010), which increases the power handling capability to 1.5A but does not allow concurrent data transmission. The Battery Charging Specification requires that the physical ports themselves be capable of handling 5A of current but the specification limits the maximum current drawn to 1.5A (so two different ports on the same machine can give different power outputs and thus the camera will tether to one port and not tether to another port on the same machine). For more specifics visit USB 2.0 and USB 3.0 Wikipedia info.
USB 3.0 requires more power than USB 2.0 and is especially noticeable when tethering at long distances. Some computers have underpowered USB 2.0 ports and are not compatible with USB 3.0.
There are some specific guidelines to both USB 2.0 and 3.0 cables:
Quick Troubleshooting Options
Dropped tethered connection while shooting. If connections are dropping while tethered, try the other USB ports on the computer to see if it works better. Not all USB ports on a computer have the same output power.
Quick Tip: If you have an iPad (not iPhone or iPad Mini), check which USB port on the computer will actually charge the iPad. They will all sync but typically only one port will charge the iPad. We suggest try tethering to that USB port. If you do not have an iPad, trial and error is the best method. Try a powered USB hub/repeater.
Capture One issues while tethering. There were some known issues with Capture One and USB 3.0.
Quick Tip: Try removing the CF/SD cards from the camera while tethering. Use Capture One Pro 7.1.6 or newer. This should fix any issues.
The Phase One IQ1 and IQ2 backs may need updating. When it comes to Phase One IQ1 and IQ2 backs, they need a minimum of firmware version 5.00 (always use the latest version). If firmware is lower, then download your firmware update from Phase One.
IMPORTANT: We recommend you download the firmware package, put it on a CF card and upgrade firmware through the menu on the camera back. Also, make sure the camera back is not connected to a camera body during the upgrade process. The Phase One Digital Back will remind you about this, but it does not hurt to emphasize it an extra time.