Tue Apr 28, 2020 3:15 am
I also own a manufacturing business, making machined parts. What this non locking lens event likely involves is a camera lens mount that is either dimensionally out of the MFT mount standard tolerances, or the mount dimensions are using up all the tolerances. e.g. sloppy and "all over" between the high and low limits of the allowable dimensions.
On these lens mounts a dimension delta by only a few thousandths of an inch makes a difference in between having a tight fit; and/or if the lens rotates fully when connected and locks on securely or not.
I recently had TWO SLR Magic lenses that would fit fine and also locked property onto my GH4 And GH5 however the lenses would not "lock on" to my BMPCC4K. They never "clicked in" to the body. Useless. Two separate lenses.
If the lens does not rotate fully when mounting, to the proper angle even if off by a very small fraction of an angle, the small spring loaded pin on the camera body will not "click in fully" into the small recessed hole that is on the lens's mount. The lens wont lock on.
I fixed my troublesome lens, making them lock properly on both the BMPCC4K and still locked properly on my GH4 and GH5. I didnt want to send my camera back to BMD.
For the fix, I had to remove metal, take off (reduce the diameter) .005 of an inch on the Outside diameter of the small screw head that is on the MFT lens in question. This small little screw on these lenses sole function is that it acts as a rotational stop. The lens must rotate an adequate amount, for the camera mount spring pin to fully seat into the lens' recessed small oval hole. Those holes on lenses vary in size slightly.
If the pin on the camera mount is in the wrong angular location, it may take a slightly more rotation of the lens for pen to engage the lens' hole. A quick fix is to install a screw on the lens, that has a smaller diameter head on that screw, allows the lens to rotate a fraction of a degree more, allowing the camera's spring loaded locking pen to engage the lens's recessed hole. Problem solved.
Time was of the essence for me, no time to ship my camera to BMD, so I modified the small screw on my troublesom lens small screw as follows. The fix did not involve the camera, and allowed all other lenses to fit the BMPCC4K as prior, and the lens I modified fit my Panny cameras after the modificaation.
As I did not have access to a lathe at the time and needed a quick fix: I removed that small screw with a small jewlers Phillips head screwdriver. I mounted a small DREMEL motor using clamps to my workbench. I gently held the small screw in the Dremels tiny chuck, careful not to over tighten it. I then spun the screw at a low RPM, and gently "hit" the outside diameter of the screw head with a small fine file. It takes some fineness. I had calipers and was able to take off mannually some metal by about .005 of an inch. Then remounted the screw into the lens. After that adjustment, the lens properly locked on the BMPCC4K and my Panny cameras.
And I too have other lenses, and adapters that fit as varying degree of sloppyness.. on the BMPCC4K than on the Panny cameras. My experience with my lenses, adapters, leads me to believe that the dimensions on the camera's mount is what we call in the machining business "all over the place".
Mike Meagher Filmmaker
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