Mamiya 7 80mm Lens: Oval Lens Mount from a Drop
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Sometimes, impact damage to a camera or lens may not be perceptible. In this case, this Mamiya 7 80mm lens arrived with the complaint that it did not mount to the body. The client told me that gravity had pulled the lens to a carpeted floor. As seen in the first photo, the lens looked fine, no signs of impact. But, not only did it not mount to a Mamiya 7 body, the focus was a bit tight.
Photo two shows the lens mount being measured for diameter and it is 66.57mm. But, moving the lens 90 degrees and measuring now shows 67.15mm in photo three. So, I started out wanting to measure the diameter of a circle and ended up measuring the major and minor axes of an ellipse. And, that will not fit well in a precision circular lens mount. The 0.58mm may not seem like much, but in this case it is huge and is the difference between go and no-go.
The problem went much deeper than just a distorted lens mount as the lens barrel itself was damaged. Ultimately, this lens was not repaired because to bring it to specs would require a new lens mount, focus helical and probably a rangefinder cam assembly and this would exceed replacement value.
