Mamiya cameras of both the single-lens reflex and twin-lens reflex medium format camera varieties used the Sekor 80mm lens as their normal lens. This means that, based on the distance from the lens to the film plane, 80mm provided the same sized image through the viewfinder as you would see with your eyes. In the twin-lens reflex cameras such as the C3 and C330, the Sekor 80mm lens came coupled with the same focal length viewing lens. Because the lens that takes the photo on this grouping contains both the aperture and shutter, you may want to repair it if it does not function properly.
Instructions
1. Uncouple the Sekor 80mm lens from your Mamiya C3 or C330 TLR camera. First, turn the right dial to "Unlock." At the right side as you face the lenses, find the main clip near the top right corner. On older cameras, there is a second, spring-loaded catch just beneath the main clip. Push this in toward the camera, and then unclip the main clip. Lift out the entire lens assembly containing both viewing and taking lenses.
2. Unscrew the four flathead screws behind the viewing lens. Then remove this portion of the lens. This lens only affects what you see in the viewfinder, not what will be recorded on film. If you have problems with this lens, you can take it apart and insert new lens elements or replace the entire lens. You may not need to do anything with this lens except to get it out of the way of the main lens.
3. Carefully unscrew the flathead screws of the bottom lens. Make certain you keep track of these screws and which ones go in which part of the lens. You can disassemble the entire lens assembly this way.
4. Use light watch repair oil on the aperture leaves as well as on the shutter's mechanism. In many cases, this will make the lens work properly again. If it does not, you may need to fix the aperture leaves and the aperture's control ring or the shutter and its control ring. You also can replace them.
5. Use needle-nosed pliers to gently straighten the filter ring on the front of the lens if you want to use filters with the lens. This is the most often damaged part of the Sekor 80mm lens because it may have been knocked or hit over the years. If it is severely bent or dented, you may need to replace it.
Tags: Sekor 80mm, 80mm lens, entire lens, lens This, main clip