How to Repair Damaged Lens Filter Thread
Often on the secondary market can be found lenses that have bent barrel front, where a filter thread, which makes it impossible screwing filters or hood. Also you can bend the barrel and independently, dropping the camera on negligence. In any case, you can partially restore the lens, and if not to the ideal external condition, at least functionally, to be able to twist the thread filter or hood. Depending on the degree of curvature may be different recovery methods. If the small deformation, you can try to gently bend it back with a wooden circular bar. But let's consider the case when the thread is so damaged that it is no longer possible to correct.
I purchased the lens Nikon Nikkor 35mm 1:2.8 Ai/s who in two places was badly damaged thread and fix it with a wooden block failed. Optics was in good condition. And I wanted to use this lens with the hood. In this case, we can just paste in the lens thread step-up ring.
My lens has a 52mm thread. For this repair we need: step-up ring 49-52 mm, epoxy glue, black thread. 49 mm - it closest diameter smaller by one step from the desired. So take our ring. If it is inserted into a barrel thread, it turns clearance of 4 mm. This clearance we compensate thread. Dilute epoxy glue, and we smear our ring on the outer thread.
Next, gently reel in this thread thread. May from time to time to grease layers wound thread glue. All we need to wind layer about 2 mm. When will we see that thread enough spreadable it again. Now insert the ring into the lens thread.
To avoid getting glue in places it should not take the fall lens front element down, and insert our ring from the bottom up, holding his hand. Check that it was exactly in the middle, without departing from the axis. And carefully put in such a state (down the front lens element) on a poly backing, so you can easily tear during the solidification of the glue.
Now you need time for the glue to solidification, it can be from a few hours to one day. You can also put on top of a burden, I used to do other lens. A day later, our lens can be used and easy twist it filters and hood.
Drawbacks of this method
The disadvantages include the need to change the design of the barrel, the inscription is now on the front ring is not clearly visible.
Yes aesthetics little affected. But I was more important functionality. Also, if you have a super wide-angle lens, the ring can produce vignetting, so before glue the ring recommend that you first check it out.