Manual Focus Lens

Manual Focus Lens
What’s the difference between switching auto-manual focus in lens & in camera?

Manual focus is just that … you use your hand to adjust the focus.

Manual mode on the camera means you manually adjust the f/stop and shutter speed using the meter in the viewfinder to choose the correct exposure

Canon T1i / 500D Video, Manual Focus, Lens: Tamron 28-200 mm