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Reparing a dented filter ring

by M. Feuerbacher, 2003.

Many used cameras and lenses you find on the market have substantially dented filter rings. This is not only a very unpleasant view - it also poses problems when a filter ring is to be threaded on. Moreover the way into the lens barrel is obstructed since the name plate cannot be removed, and hence repairs can not be carried out.

The method presented here is very simple and straightforward and you dont need many tools. The dent is pushed out of the ring using a vise and the force is applied slowly but steadily. This is better than more rapid methods such as hammering the dent out because the metal will deform plastically at lower forces if the strain is applied more slowly.

Sorry for the bad quality of the following images. I do this kind of surgery in my basement and due to the low light my digital camera produces noisy pictures.

This lens (a wide angle for a Bolex Paillard normal 8 film camera) has a respectable dent...
The filter ring is pushed against a curved surface in a wooden bar. To make this counterpart, cut a round hole into into an about 2 cm thick bar. The center of the hole should be close to the edge, so that you can approach the hole from the side.

You can cut the hole with a round saw. The diameter should be a little larger than that of the filter ring.

As a push rod I use a round wooden bar. I have filed a wedge-shaped profile in the tip to be able to apply a higher pressure.

It is advantageous to use a wooden rod because it will do no harm to the thread. The filter will push its marks into the wood and not vice versa.

The push rod is placed into the filter ring at the position of the dent like this.

Then it is put into the vise. I use a Black & Decker workmate but you can use others as well.

Apply the force slowly and have a look at the result frequently. Place the push rod in different positions in the dented part.

The dent can be removed almost completely. The dent in this lens was at the 6 o'clock position. You will always see some remainder but you will be able to use the thread normally.