My T4i does not allow manual setting of live view display gain which has been a big problem when using BYEOS frame and focus mode. I recently found that the exposure simulation mode of the camera SEEMS to base its video gain on the last known aperture when a lens was attached.
If I last used a lens at F22, then attached a telescope to do some AP, Live View would be so dark as to be useless.
But, if I opened the aperture to F2.8 BEFORE removing the lens or powering off, Live View was quite bright and useful during later AP work.
If others can confirm this, It may open up a workaround to Live View gain control in BYEOS. Perhaps BYEOS can simulate a lens aperture value to the camera if a non EF lens is attached. If so, perhaps that could be made into a control on Frame and Focus?