Installing and Operating the C-mount Camera Adapter for Operating Microscopes
Richard J Kinch
Updated: November, 2013
- Identify the following kit contents:
- Read the diagram and observe that the adapter assembly consists of three components:
- An outer fitting sleeve for the Zeiss OPMI accessory port.
- An inner lens cell which fits inside the fitting sleeve.
- A lens body which fits inside the inner lens cell.
Installation typically requires that you calibrate the focus of the lens to your particular camera, and the rotation of the
assembly to your operating microscope.
To perform these calibrations, you must separate the fitting sleeve from the rest of the assembly.
This "rest of the assembly" consists of the lens body and inner cell as a unit, which we call the "lens body-cell".
Understand that these components are held together by setscrews:
one set of three small setscrews is on the fitting sleeve, and
another set of three very tiny setscrews is on the lens cell.
- Understand that the fitting sleeve setscrews set the rotation of the camera.
- Understand that the inner sleeve setscrews set the focus and centering of the image.
- Take care when handling the loose adapter not to touch the lens surface.
- Calibrate the focus at infinity of the lens to your camera as follows:
- Loosen the 3 setscrews (1.3mm hex key) on the fitting sleeve and remove the lens body-cell assembly. Set aside the fitting sleeve.
- Screw the lens body-cell assembly into your C-mount camera. Take care when mating the fine threads, which are easily cross-threaded or otherwise damaged.
- Operate your camera so that you have a live view of the camera image with the lens assembly attached.
- Point the camera at a distant scene such as the horizon or a distant tree line seen outside a window. This scene acts as an infinity image test target.
- Observe whether the distant scene is in focus in the camera live view.
- If not in focus, slightly loosen the three setscrews (0.7mm hex key) in the lens assembly, and turn the lens body within the cell until the live view image is precisely
Use the tip of a probe, or the hex key itself, against dimples on the face of the lens body to turn the lens inside the barrel.
Tightening the setscrews may move the focus slightly, so you may have to compensate by repeating the focusing adjustment slightly in or out before re-tightening
the setscrews, to achieve a precise focus with the setscrews tightened.
- Once in focus, gently tighten the three setscrews against the rim of the lens body. Tighten the setscrews only enough to just grip edge of the lens body.
- Remove the lens body-cell assembly again from your camera.
- Reassemble the fitting sleeve to the lens body-cell assembly, gently tightening the fitting sleeve setscrews (1.3mm hex key) just enough to hold the orientation.
Turn on the in-camera mirroring feature of your C-mount camera, if this feature is available in your camera.
The Zeiss OPMI accessory ports produce a mirrored image from the beamsplitter.
Mirroring a second time in the camera thus yields a properly un-mirrored image.
If in-camera mirroring is not available in your camera, the displayed camera image will be mirrored.
- Mate the assembled camera and adapter to the operating microscope accessory port fitting, engaging the accessory port tabs to the fitting sleeve slots,
and tightening the accessory port lockring to the fitting sleeve threads.
- Confirm that the camera view is parfocal with the binocular eyepiece view, as follows:
- Obtain an image visually in the instrument binocular.
- Note that the camera will likely not yet be rotated in a proper orientation for the microscopic scene, such that the image is tilted.
- Ignore any tilt for the moment, which we will correct in later steps.
- Adjust the eyepiece diopter settings for any refraction error in the viewer's eyesight.
- Bring the view to a sharp focus through the instrument eyepieces.
- Observe that you have a microscope image in the camera view which matches the binocular view.
- The camera image should be "parfocal"; that is, the camera view is in focus when the visual eyepiece view is in focus.
- Note that parfocality depends on proper diopter settings on the eyepieces for the observer's refraction error, if any.
- Rotate the camera so that the camera image is properly oriented with respect to the binocular view, as follows:
- Observe the angle of rotation you will need to apply to rotate the camera view so that it is not tilted.
- Remove the camera/adapter again from the instrument.
- Loosen the fitting sleeve setscrews (1.3mm hex key), rotate the camera orientation that will obtain a proper orientation, and retighten the setscrews.
- Return the camera/adapter to the instrument and observe the proper orientation.
- Repeat this rotational adjustment until the rotation is properly set to remove any tilt in the image versus the eyepiece view.
- If the camera image is still not parfocal, repeat the focus calibration steps above.
- If the camera image is tilted, repeat the camera rotation steps above.
- If the camera image is slightly off center, you may fine-tune the centering by moving the lens body left/right/up/down slightly with the three lens cell setscrews,
in a trial-and-error process.