Intro: Leitz Trinovid 8x20C Center Focus Repair
This is for all who don`t like throwing things away and buy new when a little but necessary piece of plastic is broken apart.
I love to watch nature through my big and heavy Fujinon 7x50 so I decide to buy a small used Leica Trinovid 8x20C for backpacking. Bad luck for me that I have dropped it on the floor just before my first tour with it :(
The left lens wasn`t focusing after a fall of 1,5m on the ground despite a padded protection case. The front lens section inside the bino was loose and did not move by turning the focus knob like the working right side.
I opened the center part of it and found a little piece of plastic inside which broke off through the impact. This part (whatever the correct technical term is) is sliding both lens elements inside of the tubes simultaneously.
It was no option for me to send the Trinovid to Leica for repair cus it would cost me much more than another used 8x20C (even if I am located in Germany). So I ask Leitz service in Portugal for a replacement of the broken part.
Well my Trinovid was built in the 70thies and the very polite answer from Leitz service was that they do not have any spares for such an old bino. But they generous offer me a new one for 75% of the retail price :(
A simple 50 cent piece of plastic has passed away and I have to buy a new pair of binoculars? Nope!
So I tried my luck with a DIY repair finally - and it works great :)
Step 1: Remove Leatherette
Lift off the leatherette of the central "bridge" and peel it off gently. It is self-adhesive.
Step 2: Remove Top Cover
Unscrew the four small Phillips screws and remove the top cover. Now you can see the broken piece of black plastic inside.
Step 3: Remove Focusing Screw
Hold and block the focusing knob with a plier. Use a piece of thick cloth to avoid any marks on the knob. Unscrew and remove the Phillips screw on the front side (turn anti-clockwise).
Step 4: Remove Focusing Knob
Remove the focusing knob by unscrewing it completly - here you have the piece of broken Leitz plastic. There are two little grooves on the underside to make the arms more "flexible". These arms are sliding the front lens elements inside the tubes when you turn the focus knob. Through the impact the left lens element was forced forwards and broke the thin plastic arm into two pieces.
Step 5: Modify the Broken Piece
Cut away the unbroken side at the little groove. Make a new small groove on each side of the piece with a Dremel or any other milling device. Glue in a thin brass stripe on each side with 2K epoxy glue (like UHU plus).
Step 6: Trimming the Brass Stripes
Put in the repaired part after the epoxy fully dried and mark the proper length with a pencil or needle. Remove the part again and cut it at the marks. Now trim the width with a file until they fit the recess of the sliding rods exactly. Bent them slightly and carefully down to imitate the flexibilty of the plastic part.
Step 7: Put All Together Back in Place
Screw in the focusing knob and check out if both arms are running free without touching the border. Screw in the front screw and tight it gently with plier and cloth again. Put back the top cover and clean it with alcohol or cleaning gas. Stick on the leatherette which should stick without any trouble again. Now go out and have fun with your working Trinovid 8x20C.
I guess it will work with other Trinovids as well.