What is FocusLock?
FocusLock is the first method of focus that uses real-time feedback. Most methods of focus, including backlash compensation and temperature compensation, work by modeling the focus against a correlated physical parameter. These models can then be used to partially correct for changes in focus, however they cannot correct for any changes that fall outside their models. FocusLock uses a different approach. By introducing an astigmatism, an optical aberration, into the guide image FocusLock is able to detect drifts in focus in real time and correct for them. This means that the system will correct for any source of poor focus, even if that source has not been modeled.
Using the ONAG from Innovations Foresight both cameras, the main and guide, are par focal and use the same focuser. This means that any change in the focus in for the guide camera will also change the focus of the main camera. When FocusLock detects a focus offset it will correct it for both systems, keeping the main camera in perfect focus.