Back Focus Instructions

1/22/2009
Back Focus Adjustment
When installing a lens onto a camera you may have to adjust the back focus in
order to have proper focus. Use the following methods to set the correct back
focus:
For Fixed Focal Length Lenses
1) Attach lens to camera and turn camera power on.
2) Place a neutral density filter (CBF-1) in front of the lens and open the iris
to its widest position. (If lens has an auto-iris, the dark filter will cause the
iris to open automatically). Note: It is important for the iris to be fully open
during the following procedures.
3) Set the focus rings on the lens to the infinity position.
4) View a distant object (the more telephoto the lens is, the farther the distant
object should be).
5) Adjust the mechanical focus* on the camera to bring the image into the
sharpest focus.
6) After back focus is set, you can adjust focus and iris to desired positions.
For Zoom Lenses
1) Attach lens to camera and turn camera power on.
2) Place a neutral density filter (CBF-1) in front of the lens and open the iris to
its widest position. (If lens has an auto-iris, the dark filter will cause the iris
to open automatically). Note: It is important for the iris to be fully open
during the following procedures.
3) Zoom the lens to the telephoto position (“Zoom In” position on the lens
controller).
4) Operate the lens focus to get a sharp picture (“Focus Near” on lens
controller).
5) Zoom lens to the wide position (“Zoom Out” on lens controller).
6) If picture is out of focus, adjust the mechanical focus* on the camera to
bring image into the sharpest focus.
7) You can repeat the above steps to fine-tune the back focus if you need to.
8) After back focus is set, you can adjust zoom, focus and iris to desired
positions.
*See your camera manual for instructions on how to adjust the mechanical
focus (Also known as back focus)