B+W CPL front element has spun loose from ring (SOLVED!)

[ahsanford]

You don't see that every day. It appears my first B+W filter has finally failed on me. 77mm Kaesemann CPL -- a commonly used filter for me. Lasted just under 5 years of (enthusiast) use.

I noticed it when I was cleaning a smudge / finger print off the the filter. I was using my microfiber + ROR on it, and despite securely holding both rings of the CPL stationary, the front/outer CPL glass element was still moving -- the front element has become detached from the CPL turning ring.

Looks like I just created this event this evening with my (fairly gentle) cleaning. The glass isn't uncontained / at risk to fall out, and being the outer element, it has no risk of contacting the lens front element. But it is free to spin. I can still turn the CPL ring and it looks like it still follows the ring, but now that it's loose there's no guarantee it won't loosen further over time and just be a passenger as I turn the ring.

A few questions for any filter-failure veterans out there:

• What's the warranty on filters? I don't want to crack the rings open and try to tack it down again, so I'm presuming this things a loss. B+W has a great rep, so I'm wondering if they might still replace it.
  
  
• For those who have had this happen before, what's the harm in continuing to shoot with this CPL until I replace it? Seems fine, but if an internal bit or bob of plastic/metal is floating loose inside and it might find it's way to the lens' front element, I'll pull it ASAP.
  
  

Thx,
A

 

[brad-man]

Re: B+W CPL front element has spun loose from ring

I have not had any of mine fail yet, but this appears to be the place to deal with it. It seems a $45 flat fee would apply if it is out of warranty. Email them and find out. Good luck.


https://www.schneideroptics.com/service/service.htm

 

[ahsanford]

Re: B+W CPL front element has spun loose from ring

Just wrote them now. Presuming the 1 year warranty has long expired, I'm expecting at least $45 to get it fixed when it's $89 new.

Likely just buying a replacement, but has anyone ever tried cracking one of these things open? Is it a one way trip?

- A

 

[ahsanford]

Re: B+W CPL front element has spun loose from ring

I just fixed it. Holy cow. It's fine.

Post upcoming...

- A

 

[ahsanford]

Re: B+W CPL front element has spun loose from ring

Okay, here's what I did:

1) Just checked YouTube to see if anyone has ever torn down a B+W. Didn't find one. But this video for a variable ND repair was key:

https://www.youtube.com/watch?v=-mDcyeYey-g

2) Offhand, with my filter I didn't recall a similar notch on the inset/cap ring (that holds the sandwich together) that the video showed, and that's logical for a higher quality (and possibly internally gasketed) Kaesemann design. Sure enough, upon pulling the offending CPL out and having a close look at it, I just saw the signature B+W black matte beveled little edge around the ring -- see pics. It did not have a screwdriver notch.

3) I thought this beveled ring might actually be integral to the larger/outer CPL focusing ring and the entire filter was somehow magically assembled with special presses/fixturing at Schneider. But, just for fun, I tried to see if I could turn that beveled ring like with the different style filter in the video. To avoid scratching it (which might leave naked brass underneath, potentially leading to a reflecting into the FOV), I used an eyeglass repair sized screwdriver with a tiny 'egg' of the non-sticky side of gaffer tape. If it was modular, I didn't think a single pressure point would loosening it -- that I'd need a 75mm-ish circular rubber 'something' pressing down to get it out -- but it actually spun freely with not much effort. Culprit found.

4) At that point, I just reversed course and tightened it back down, taking care to make sure the front CPL glass element was well-centered as the very periphery of the glass (normally trapped under the beveled ring) appeared to not be polarized and I didn't want that in the FOV.

5) Turns out (at least in this design) that overtightening this beveled ring tightens the entire CPL ring function. I overdid it a bit and the CPL ring was a little tight.

So I have to presume my rather overzealous cleaning habits + a CCW cleaning spiral with the microfiber is what did me in. CW spirals will be the norm from here on out, and the $89 for the replacement can stay in my pocket.

- A

 

[Mt Spokane Photography]

Good Job! I'm glad you figured it out. I have a set of spanner wrenches that fit into small notches or holes for taking camera lenses apart, I have never looked at filters though.

 

[pwp]

Over the years I've had multiple polarizing filters fall apart. I've tried in vain to re-assemble them, but gave given up every time and replaced the item. These days I always keep a spare handy.

-pw