i308 Camera Back Focus Adjustment Procedure
? E. Altman, Aug 14, 1997
Back Focus is the correct distance between the camera image sensor and the plane of the C-mount which allows an image to focus identically in both the microscope and the monitor.
If the focus differs only slightly from the eyepieces to the image on the monitor, check the focus adjustment on the eyepieces. Each eyepiece has a fine focus adjust and may be adjusted to another person’s eyes. Focus the image in the monitor first, then focus the eyepieces to each eye. Use low magnification for this adjustment.
If there is a large variation in the focus, set the eyepieces at zero and turn the microscope to the highest magnification (do not use an oil immersion objective) and focus the scope through the eyepieces. If the focus on the monitor is off, loosen the knurled lock ring behind the C-Mount adaptor on the camera head. Then loosen the set screw(s) for the C-mount adaptor on the photo tube of the microscope. Rotate the C-mount adaptors together until you attain a focused image in the monitor. Do not rotate the camera head as you may twist and damage the camera cable.
Turn the microscope back to low magnification and again focus the scope through the eyepieces. If the focus on the monitor is still off, rotate C-mount adapter body again to attain a focused image on the monitor. The camera should now be parfocal with the scope.