# The importance of clean lens contacts in the R environment



## axtstern (Dec 17, 2022)

Hi folks, this topic might be related to another thread in regard to R cameras freezing up.

I have quiet a large lens collection, only two of them are RF Lenses all others are EF lenses.

A big part of my collection are lenses 10 to 30 years old and I happily torture my new R7 with them to find out how they behave.

As some might know I use not only the Canon EF to R adapter but also a Viltrox Speed booster. The phenomenon I report happens on both but here I talk only about the Canon adapter.

With some lenses my camera locks up or after a few minutes of perfect behavior the AF start to stutter. Drove me mad so I started to investigate.

Factors I excluded first:


The Canon adapter (the Vilcrox also) is sound engineered, no wobbling, so the connection between the contacts should not be an issue.
I skipped lenses with dodgy protocol implementation like Tamron 35-105 2.8 (1994) or several Sigma fisheyes (1992-1998)
I skipped lenses with enormous energy consumption which already have proven to lock up my EOS 5dMK3 and EOS 1dxMK2 (Sigma Lenses again)
*All issues with AF stutter or camera freezing up or the “some error occurred, restart your camera” disappeared once I cleaned the lens contacts.*

So I excluded Lenses which work so far flawless but which have wear and tear on the contacts because of being mounted 1000 of times in 30 years (Tokina ATX 28-70 2.8, Canon 20-200 2.8 L, Canon 400 2.8 L and Canon 85 1.2 L)

*Again: all errors done after swiping the contacts*

Now that sounds like a pretty simple explanation…. But it isn’t.

I clean my front and back elements and sensors whenever they are dirty. I also clean the lens contacts when I buy a used lens. But cleaning the contacts is usually not necessary. I have frequently used and changed lenses that I have never cleaned or not cleaned for maybe 15 years. Those lenses worked on the analog EOS 10, on the EOS 30d, on the EOS M and now on the R they show issues. So if a dirty contact seems to be the issue, previous EOS models could not be bothered to fail.

So my question is how many factors have changed in the evolution of the Canon bayonet?

Of course there are more contacts now, but the lenses in question don’t have them.

Is an R camera relying on contacts in existence since the first EOS but which never have been critical before? Do they read a contact which before just transferred juice? Did they change protocol, voltage or frequency?

I do not know enough to make a guess, but for my issues cleaning helps and that means from now on my after use lens care routine gets enriched by a swipe of the contacts.

Still I would like to know whats the driver behind. Maybe the more technical people here can make an educated guess or shed some light?


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## Mt Spokane Photography (Dec 17, 2022)

Typically, the issue with contacts is fretting corrosion. Microscopic scratches in the protective gold and nickel underplating can reach to the base metal. Then, even moisture in the air can start the corrosion process and the contact can get a thin and invisible layer of a metal oxide film which resists low voltages often used in electronic signals. The film is usually wiped away when the two parts of the contact rub together, but not always. The corrosion can be easily wiped away. 

I once had to analyze why the trigger circuits for a payload in a cruise missile tested as failed. The gold-plated connector in the circuit was replaced on all of the missiles and the failed ones sent to me for analysis. They all tested perfectly by the time I got them, we analyzed them for contamination, even looking at surfaces with our electron microscope. Nothing out of spec could be found.
We gave an opinion that there was dry film corrosion which was wiped away when the connectors were disconnected for removal and that finding proof of it was impossible. Using gold plating was probably not the best choice for that application, but there was really no great choice. The missiles were stored underground for over 20 years and periodically the circuits were tested using very low voltages and currents. I think they finally decided to test more often to see if it happened again. We all hope that those devices are never used, but if it's necessary, they need to work every time.


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## unfocused (Dec 17, 2022)

I’m glad that cleaning the contacts helped you with your lock up issue, but I doubt if there is any meaningful correlation between the two. The freeze ups occur with new or nearly new lenses. Probably just a coincidence.

It seems as though almost everyone has their own ideas about what causes Canon’s mirrorless cameras to lock up. Because the instances are random and inconsistent it lends itself to all sorts of magical solutions. 

Canon does seem to be slowly working their way closer to a solution, but the fact that they have yet to find a solution that works consistently indicates to me that this is a complicated issue. 

It’s entertaining for us to play amateur sleuth but I doubt if any of us will ever discover a real solution.


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## Del Paso (Dec 17, 2022)

Mt Spokane Photography said:


> Typically, the issue with contacts is fretting corrosion. Microscopic scratches in the protective gold and nickel underplating can reach to the base metal. Then, even moisture in the air can start the corrosion process and the contact can get a thin and invisible layer of a metal oxide film which resists low voltages often used in electronic signals. The film is usually wiped away when the two parts of the contact rub together, but not always. The corrosion can be easily wiped away.
> 
> I once had to analyze why the trigger circuits for a payload in a cruise missile tested as failed. The gold-plated connector in the circuit was replaced on all of the missiles and the failed ones sent to me for analysis. They all tested perfectly by the time I got them, we analyzed them for contamination, even looking at surfaces with our electron microscope. Nothing out of spec could be found.
> We gave an opinion that there was dry film corrosion which was wiped away when the connectors were disconnected for removal and that finding proof of it was impossible. Using gold plating was probably not the best choice for that application, but there was really no great choice. The missiles were stored underground for over 20 years and periodically the circuits were tested using very low voltages and currents. I think they finally decided to test more often to see if it happened again. We all hope that those devices are never used, but if it's necessary, they need to work every time.


Very interestingt, thanks!


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## axtstern (Dec 18, 2022)

> I doubt if there is any meaningful correlation between the two. The freeze ups occur with new or nearly new lenses. Probably just a coincidence.


You are wrong. For my lenses I was able to reproduce the rough focusing and the "an error has occured, restart your camera" at will. Cleaning the contacts on the lens removed this issues.

I agree that this is not valid for people who manage to freeze up their camera with brand new dedicated R lenses, but as I assume that there is more EF than RF Glass currently used on R cameras I suggest to try what I discovered and helped for my individual situation.


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## unfocused (Dec 19, 2022)

unfocused said:


> I’m glad that cleaning the contacts helped you with your lock up issue, but I doubt if there is any meaningful correlation between the two. The freeze ups occur with new or nearly new lenses. Probably just a coincidence.





axtstern said:


> You are wrong. For my lenses I was able to reproduce the rough focusing and the "an error has occured, restart your camera" at will. Cleaning the contacts on the lens removed this issues.
> 
> I agree that this is not valid for people who manage to freeze up their camera with brand new dedicated R lenses, but as I assume that there is more EF than RF Glass currently used on R cameras I suggest to try what I discovered and helped for my individual situation.


First, sorry if I offended you. After re-reading your original post, perhaps you weren't suggesting that cleaning the contacts would prevent or cure lock ups. That's how I read it, but I may have read too much into it.

Just a few more points though. You state that you were able to reproduce the issues, but how were you able to reproduce them after you had cleaned the lens contacts? Did you get them dirty again? Or are you saying that you did not have issues with lenses after you cleaned the contacts? If so, then yes, I would agree that dirty contacts were a problem for you. And, certainly, it is good advice for people to check their lens contacts. But, I'm not convinced that is relevant to what most people experiencing lock ups have faced. 

Remember, you are a sample size of one and in all the other threads and posts on this topic, I don't recall anyone else who found their lens contacts were dirty and cleaning them cured the issue. It seems highly unlikely that such an obvious solution has not been discovered by others and especially, not by Canon.

As I said in my original response, I'm glad your solution worked for you.


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## axtstern (Dec 19, 2022)

No offense taken and thanks for the friendly reply. English is not my mother tongue and I might sound more insisting than I want to be. 

Now how I reproduced the errors: 

Well I say errors but I talk about failures. And of course I talk not about byzantine errors but about intermittent failures.
Just for the example: 
EF 300 4.0 L used for about 200 pictures during a basketball match, occasionaly swapped with other lenses.
Three or four failures in 200 shots, AF starts to stutter, lens get substituted by Sigma 120-300 4,0
Two days later about 400 pictures during an Ice hokey game, again 3-4 times the lens AF starts to stutter
Emergency substitute: Yongnuo 100mm F2. After 50 pictures with the Yongnuo the camera comes up with "An error has occured, try to switch your camera of and on" However camera simply reboots afterwards and comes up working again.

Troubleshooting session at home: connecting about 25 lenses over a boring work from home conference and taking roughly 2000 shots of the birds in the garden. 5 lenses produced occasional AF stutter. 2 of these lenses managed to lock the camera, Adapters were randomly changed (Viltrox/Canon).

Cleaning session: airstream, alcohol cloth, brush

After cleaning session:
Christmass show of local marching band, putting all all suspicious lenses into action. Alltogether more than 2000 shots, with no more incidents, Neither the 300 F4.0L nor the 200 1.8 L nor the Yongnuo lens etc... No more issues at all.


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