[phidias81]

Hello my lens SMC Pentax-DA L 50-200mm F4-5.6 ED WR got broken last weekend while shooting during a concert at the beach. It was on the tripod mounted close to the ground, and the tripod whit the camera on just lost the balance and fell in front hitting the lens. The glass had no damages at all, but the zoom mechanism is not working correctly anymore. Its range is limited now between 200mm and 100mm, and even within this range, it cannot focus (either automatic or manual the same), though the focus ring is not blocked and going all the way. So basically the lens is totally unusable at the moment.
I know many would suggest to just take a second hand one, but I want to try to fix it.

I already tried to disassemble it, partly following this guide for a different zoom lens.

I uploaded a video on Youtube (sorry for the awful quality but it gives an idea), that is possible to see on this link

Youtu.be

Youtu.be

In the first part I show the problem described above.
At minute 0:30 I start to show the disassembled lens. After taking out the mount, there are basically three main parts. Two of them are totally ok, the problematic one is the central element. I show this piece starting at minute 1:20. Basically it looks like the end of the ridge is getting stuck (1:28) on the rim. It might be also engineered to work like that, I'm not sure. By pushing the ridge a little bit on the side manually, then it goes all the way inside.

It might be possible to disassemble the element more: I can take out the diaphragm and see inside the tip of some screws that are not visible from the opposite view. Probably they are hidden below a black sticky surface, but I haven't tried to remove it.

There is also a little groove (2:06) that is really difficult to keep aligned to reassemble the lens. It was really difficult to do it, maybe because it was my first lens disassembled.
I hope that somebody will be able to give me a good advice on how to fix it!

[phidias81]

Any help? I would be happy even to fix it even with limitations, in example only range 100-200mm or even fixed at 200mm if no other options are available

[petez]

Not sure I can help except to encourage you to keep at it 'cause I feel your pain. This very afternoon I spent 6 hours on my 16-45 lens which basically had the same problem. I got it apart and it took numerous attempts at getting it back together correctly. In the end, I dont know exactly what I did to fix it OR get it back together correctly, However, its working now.. not perfectly as the zoom has 1 spot where it sticks and takes a bit of force to continue. But it's working!

Try this site for some help:
https://www.flickr.com/photos/fluffyrazor/7729728594/in/set-72157630944498102

There some info at the bottom of the images that may help.


Best of Luck.

Pete