Wow...thanks for all the great suggestions! I'll try the tapping first, then filter wrenches, then heat, then pb blaster (penetrating oil), then heat and oil combo...and if none of this works...its dremel-time! Will report results!
I recall reading in my Leica Manual above a technique for removing stuck filter from the front thread of the lens. It's simply to pinch the filter's metal mount ring between the thumb and forefinger at one point on its circumference, then start to turn the filter while holding the lens. I've done it before and it does work. it seems that grabbing the filter's mount with these same fingers 180* apart on its circumference (as normally done) actually deforms the circular mount ring into an oval shape - its diameter shrinks between the fingers but grows in the other direction. This growth results in friction between the ring and lens, causing resistance to the applied torque - thus binding. Hope this description makes sense.
All of mine have come loose after being put into a freezer (below zero F) for several hours. Different metals contract at different rates, and a gap seems to open between them.
Kent in SD
In contento ed allegria
Notte e di vogliam passar!
Some filters have brass rings, some have aluminum rings and some have plastic rings.Originally Posted by Jerry Bodine
You have to have some pair of fingers to deform brass rings!
Bob, what I've described involves elastic deformation of the ring into an oval (i.e., it returns to its original diameter when the force is removed). Perhaps you're thinking of permanent deformation, which I agree would certainly exceed the capability of the fingers to produce. But you may be aware that there are specs that control the tolerances between the dimensions of the ring's external thread and the mating thread it fits into, such that there is but a VERY tiny gap between the two threads. Only a rather small force is needed with the fingers to close that tiny gap when the ring's diameter tries to grow into an oval shape and is met with resistance from the internal thread. When that gap closes under the squeezing force of the fingers, friction is created between the two threads that causes them to bind. Yes, the modulus of elasticity of brass is on the order of 50% higher than aluminum and would need about 50% higher finger force, but still not insurmountable.
Jerry, as you probably know we were first the distributor of B+W filters and then Heliopan and Rodenstock filters in the USA.
While you might be able to squeeze an aluminum mount B+W filter rim or an aluminum rim Rodenstock mount you would have to be as strong as a gorilla to squeeze a brass mount enough from any of these three manufacturers.
As part of our displays at shows we showed how the brass rings were made as well as the brass step up rings. If they were brass you won’t do it with your fingers!
I'm curious, Bob. Can you say whether there is a gap between the brass rings and the glass filters, seems like there should be? And if so, what might that gap be? I ask because if the ring-to-glass gap closes - thus loading the glass - before the thread gap closes under finger force, there could never be any binding.
Not that I’m aware of. The retaining ring is snugged tightly against the glass and the glass sits directly on the ring. At least with the ones that we distributed.
I’ve had to deal with this several times. I just throw the lens in the freezer for a few hours and then breath heavily on the filter, or use a hair dryer set to low. It also helps to tap on the filter, firmly, but gently. It works every time!
Posting Permissions
Reply With Quote
Bookmarks