Dealing with stuck filters

[Ramsden]

Hi folks 

EOS90D and 7, about to be 8 lenses. Recent posts have revealed how common the problem of stuck filters is amongst us. I got mine down to two, but they were STUCK! 

As an engineer I genuinely apologies for this photo of the method I resorted too, to remove the stuck filters. But I was extremely careful, and eventually got them off my lenses. I have to tell you, that even with these plumbers grips, it was difficult. 

Lenses are all now cleaned and in good condition, awaiting new clear glass filters and maybe a trial with magnetic filters. All options remain open, but I've just fitted a new (expensive) clear 67mm filter, and its 'clear'! How on earth do you assess clear glass?

 Ramsden 

[Ramsden]

Good morning 

I tend to like this idea, and agree with Zak. I don't like the idea of any substances being near my camera mechanism. It just doesn't feel right. 

The camera feels like a 'dry' mechanism and works well, down to excellent engineering.

Ramsden 

[Ramsden]

One further thing, if you examine a lens filter after it has been stuck, it appears to have a grey substance on the threads.

I wonder if this is the result of electrolysis, when an electronic current passes between dissimilar metals, and the weaker metal corrodes. On bigger structures the engineers use cathodic protection to manage this process.

Given that my filters, up till now, have been cheap uv's, that would make sense.

Just a thought...

Ramsden 

[SignifDigits]

@Ramsden as an engineer I'm sure you are ware that what you experienced was bimetallic bonding due to galvanic action or oxidation.  If the lens threads are brass, then brass would be the right choice.  If aluminum, then aluminum.  As many moden lenses use aluminum, brass threads is a great marketing ploy but a bad choice as there is natural galvanic action between aluminum and brass due to humidity in the air.  Brass was perfect when lens threads were brass, but not so with aluminum.

From the AI:  "Brass and aluminum cause galvanic corrosion when in direct contact, with aluminum acting as the sacrificial anode. In the presence of an electrolyte (like moisture or water), electrons transfer between the metals, causing the aluminum to rapidly dissolve and physically fuse to the brass."

Of course aluminum DOES oxidate (aka rust), just creating layer of aluminum oxide instead of the iron oxide rust that we all know of as "rust".  

I'm assuming what you saw was aluminum oxide as it is grey (often spelled gray across the pond).

If we put anything on the threads it should be a corrosion inhibitor.  None of the materials mentioned thus far qualify.  CRC (and others, even the company that makes WD-40) make products designed for this purpose. 

Paint (hopefully anodized) on both threads is the best protection if both are aluminum.  Anodization is preferred over regular paint as it is more permanently bonded.  I'm assuming that Canon and the better filter manufacturers use anodization.

I notice that several of my Canon lens threads are plastic.  This is perfect.  It may seem cheap, but the threads on my RF 70-200 f/2.8 L USM Z lens appears to be plastic and I don't think anyone would call that a "cheap" lens.  The most recent EF version of this lens was of aluminum.  If your lens threads are plastic you don't need to apply anything as aluminum oxide does not adhere well enough to plastic to cause concern.

The only time I would consider a treatment would be if I were using brass to aluminum (lens to filter) or vice-versa or if both the same materials if they were going to be on "forever-ish" and/or in a harsh environment.

Of course, anytime your lens threads get wet, you should take the filter off to let them dry.  And anytime you install a filter it would be wise to inspect them for signs of degradation of the coating on the threads.

I take my lens filters off for more serious shooting, and that seems to work for me with no treatments.  If I were leaving one on "forever" kind of thing I would attempt a layer of teflon tape as superior to a coating.  That said, getting that in place would be a nightmare, so I really cannot recommend it (I gave an attempt whilst writing this and wholly do NOT recommend it as practical, just technically superior) as a real-world solution.

Thus, what I do and personally recommend is putting a filter for transport, etc, and taking the filter off and counting on the lens hood to protect your lens during use. I install high-quality clear lenses for those times I forget or want to keep, something off the lens (as when I'm in a mist at the bottom of the waterfall when take the filer off and on)  If I use a CPL (and I have not yet) I would only install it during shooting.  And when things are wet, bet sure to take the filter off so that it's not trapped in the threads.

That is a cool looking tool, by the way.    I might have some tool envy 🙂

[Ramsden]

Hi 

Thanks for a great response to my message and some great takeaways. You made me laugh with the Teflon tape. I, like 000s of other folks have probably ended up in the same mess doing some home plumbing. And - it was on my list of things to try on the filters - but I'll pass on that one  now.

But from what you wrote, I was on the right track,  particularly with dissimilar metals. 

In the 1970s I worked on the North Sea gas pipelines  covering a couple of thousand miles. We used to weld a small boxes with 'soft' metal inside onto the pipeline, every few miles. The box was earthed by a cable, and I'm sure a small electric current ran through the pipeline so it acted as a sacrificial anode. 

But what I really like is your idea of just using filters for transportation and take them off when shooting. Now thats the most logical and (with hindsight) sensible thing to do. Since last week, I've ordered 3 B&W clear filters- at great expense. But your idea has stopped me buying anymore, in fact they might get returned!

I'm not particularly fanatical about my photographic work, but I lean towards letting the camera do most of the work, as sitting in front of a computer doesn't appeal to me.

Thanks again 

Ramsden