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TM-4200GE Hardware
8.2.4Attaching the Camera Lens
The TM-4200GE camera accepts 1.2-inch or larger format size C-mount lenses. To attach the C-mount lens1 to the camera, carefully engage the threads and rotate the lens clockwise until it firmly seats on the mounting ring. Do not force the lens if it does not seat properly. Some lenses with extremely long flange backs may exceed the mounting depth of the camera.
8.2.5Adjustable Back-Focus
Before cameras are shipped, back focus is carefully set using a collimator, oscilloscope and other specialized equipment. While the factory-set focus serves well in most cases, an adjustable back focus makes it possible to improve image sharpness when using lower-cost zoom lenses, custom optics, or in unusual parameters.
There should be an obvious need to refocus the lens before attempting to change the back focus. This is a very exacting task. Some cameras have been returned to the factory to reset the back focus after failed attempts to change the focus by customers. It might be wise to label cameras whose back focus was adjusted.
1.The camera must be connected to a monitor before attempting to adjust the back focus.
2.To back focus the camera, first attach a C-mount lens in the mount. Be certain that the lens is prop- erly seated.
3.Next set the lens focus to infinity (if the lens is a manual iris, set the iris to a high f number while still retaining a well illuminated image).
4.Loosen the three miniature hex set-screws (use a 0.9 mm hex wrench) that lock the focus ring in place (two screws for a CS-mount). Slowly turn the lens and focus ring assembly back and forth until you obtain the best image of the desired object. This sets the back focus. Once the best image is obtained, tighten the focus ring set-screws until they are snug. Do not over-tighten the screws.
Note: Mini-bayonet cameras adapted to C-mount do not have the back focus feature.
FIGURE 52. Back Focus Set-Screw Locations
Loosen the three 2mm screws around the perimeter of the C-mount lens collar (two 2mm screws for a CS-mount) to adjust the back focus. Unless you absolutely must, do not attempt to adjust this focus.
1.C-mount to F-mount and C-mount to K-mount adapters are available for larger format lenses (35mm). Check with local photography dealers for these lens adapters.
