Epson R-D1s - Manual (Page 16)

16 Getting Started
Removing an M-mount Lens
1. Press the lens release button and turn the lens body
counterclockwise.
2. Pull the lens straight out.
Mounting and Removing an L-mount Lens
For an L-mount lens, you need an optional M-bayonet adapter ring.
Attach the adapter ring to the lens, then install the lens on the camera
as you would an M-mount lens. When you want to remove the lens,
the procedure is the same as for an M-mount lens.
Selecting the Focal Length
You need to select the focal length of the lens mounted in order to
display the correct bright-line frame that indicates the field of view
covered by the lens. The automatic parallax correction feature allows
you to capture what you see in the selected bright-line frame. Turn the
frame selector lever to select 28 mm, 35 mm, or 50 mm to match the
focal length of the lens being used.