C-Mount Back Focus Adjustment User's Guide

Lumenera recently announced that all INFINITY 1, 2, 3 and X-21 cameras include a C-mount back focus adjustment ring, enabling users to easily improve parfocality with a microscope trinocular port.

Digital cameras have become a basic tool for microscopes. Mounting a camera on a microscope requires the addition of a trinocular port to the basic microscope stand. Light from the sample passes through a prism splitting the beam into two paths, one to the microscope's eyepieces and one to the camera. When these two light paths vary in distance, the sharpness of the sample viewed through the eyepieces and the camera may be different. These slight differences can be corrected using the camera's back focus adjustment ring by following these next steps:

Eyepieces:

1. First ensure that the microscope eyepieces are adjusted. Beginning with the eyepieces' fine adjustment ring set to zero, follow the manufacturer's instructions on how to adjust the eyepieces to accommodate for slight variations in the user’s eyes.
2. Once the image in the eyepieces is clear, the back focus adjustment on the INFINITY camera can be set to match.

Camera:

Please note:
Care should be taken not to twist or kink the cables attached to the camera, and to keep the back focus ring and other adapters from turning along with the camera body.

1. Remove and thread your microscope’s C-mount adaptor into the camera's black back focus adjustment ring. Place the camera and adaptor back on the microscope.
2. If the image on the monitor is out of focus compared to the eyepieces, lift the camera and adaptor slightly. If this improves the focus, loosen the silver locking ring on the camera’s C-mount and rotate the camera's black back focus adjustment ring one half turn counter-clockwise. Place the camera back on the microscope and verify the focus. It may be necessary to perform this adjustment several times before achieving perfect focus between the eyepieces and the image viewed on the monitor.
3. If lifting the camera and adaptor slightly does not improve focus or makes it worse, loosen the silver locking ring on the camera C-mount and rotate the camera's black back focus adjustment ring one half turn clockwise. Place the camera back on the microscope and verify the focus. It may be necessary to perform this adjustment several times before achieving perfect focus between the eyepieces and the image viewed on the monitor.
4. Once the focus has been successfully adjusted, carefully tighten the silver locking ring and tighten the locking screw on the c-mount adaptor with the INFINITY camera facing the front of the C-mount microscope.

Users can now adjust the back focal plane of their lens to the back focal plane of their INFINITY camera’s sensor. Completing this adjustment will require the use of a lens with an infinity focus setting.

1. Thread the lens into the INFINITY camera’s C-mount.
2. Loosen the silver c-mount locking ring.
3. Set the lens ring to its infinity position and position the camera to view an object located at infinity (a minimum of 25M distance).
4. Rotate the black back focus adjustment ring until the object is in sharp focus, taking care to not loosen the lens.
5. Tighten the silver c-mount locking ring, without moving the position of the black back focus adjustment ring or loosening the lens.

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