# Mount broken?



## mnclayshooter (Jul 5, 2016)

Over this past weekend, I was photographing the ships coming into and out of Duluth Harbor and in my hotel room, I found a small tab of metal laying on the white comforter on the bed... right in the area where I had just changed a lens. I investigated a bit and found that one of the three equally spaced mount components circled in red have what appears to be a piece of spring steel (maybe a different metal or some alloy) behind it. The piece of metal on the bed matched up to those tabs (or at least half of one of those tabs). 

My questions: 

1) has anyone else ever broken one of these? I have no idea how it could possibly break... there's no way you could reasonably pry on them - they're inside the mount. 

2) The camera appears to work just fine without it, and the mount seems solid... any reason I should urgently get this back to Canon? 

3) The third - the body is out of warranty at this point (obviously it isn't a 5D4 - I just snagged the photo from canon rumors to use it to illustrate the location of my issue). Any bets on the cost of repair? 


UPDATE: I think I have figured out a little more... the attached photo shows an EF-S mount and the spring part that I need. Does anyone by any chance have a link to or a part number listing to make searching the spring "ring" a little easier"


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## 3kramd5 (Jul 5, 2016)

How the heck did that come out? Screws loose enough to gap the mount from the body when you pull a lens off? If it were me, I'd send it to canon.

It doesn't looks like a shim. Random thought: the spring tabs may be there to provide contact for chassis grounding to the mount.


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## Mt Spokane Photography (Jul 5, 2016)

I'd suggest sending it in for repair. That mounting ring is aligned parallel to the sensor with some special tools, removing it can destroy the alignment, particularly if you do not put it back exactly as it was installed (don't rotate it). The spring should be available from Canon. Give them the model and serial number, and inspect the spring closely for any markings that may indicate a variation in thickness.

The lens mount is one of the most accuracy sensitive parts of the camera and great pains are taken with them.

That ring is never removed even in a complete teardown of the camera to the mirror box, it stays mounted. Once removed, a whole bunch of adjustments and measurements are needed. 

I'll be happy to e-mail you the section of the service manual for a 5D that describes the alignment process, its similar on all the DSLR's.


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## mnclayshooter (Jul 5, 2016)

That was my thought too - re: the grounding. I don't think there's anything "smart" about the ring... I've been digging - for other bodies and for the 1.4x and 2x extenders, the part is called Mount, Spring. I've found part numbers for a few other bodies, but for some reason, they have different part numbers for what appears to be the exact same part. 

For clarity, the whole ring didn't come out - just the small tab circled, broke off.


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## mnclayshooter (Jul 5, 2016)

Mt Spokane Photography said:


> I'd suggest sending it in for repair. That mounting ring is aligned parallel to the sensor with some special tools, removing it can destroy the alignment, particularly if you do not put it back exactly as it was installed (don't rotate it). The spring should be available from Canon. Give them the model and serial number, and inspect the spring closely for any markings that may indicate a variation in thickness.
> 
> The lens mount is one of the most accuracy sensitive parts of the camera and great pains are taken with them.
> 
> ...



That was my thought as well, just had thought it might be a pretty simple fix. I don't think there's any way you could accidently mount it rotated - the lens index mark and the screw holes/lens retention pin wouldn't line back up. I hear you on the precision needed though. That's the part that seems pretty daunting.


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## Mt Spokane Photography (Jul 5, 2016)

mnclayshooter said:


> Mt Spokane Photography said:
> 
> 
> > I'd suggest sending it in for repair. That mounting ring is aligned parallel to the sensor with some special tools, removing it can destroy the alignment, particularly if you do not put it back exactly as it was installed (don't rotate it). The spring should be available from Canon. Give them the model and serial number, and inspect the spring closely for any markings that may indicate a variation in thickness.
> ...



The spring for the 5D P/N is CS2-7205. Its probably the same for all the camera bodies, but Canon could tell you. I did not see any variations in the parts catalog, the sensor has shims and the focus screen has shims, but none for the mount. 

After looking at the parts list and taking into account that the mounting flange has not changed, I'd order the spring and just re-install it. Be careful not to lose the lens locking pin and spring.


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## tolusina (Jul 5, 2016)

Mt Spokane Photography said:


> The spring for the 5D *P/N is CS2-7205*. Its probably the same for all the camera bodies, but Canon could tell you. I did not see any variations in the parts catalog, the sensor has shims and the focus screen has shims, but none for the mount.
> 
> After looking at the parts list and taking into account that the mounting flange has not changed, I'd order the spring and just re-install it. Be careful not to lose the lens locking pin and spring.



Oh my, you're good. Seriously. 
Highlight and right click on that part number finds this;
https://www.amazon.com/Sparepart-Canon-Spring-Mount-CS2-7205-000/dp/B003D2S9S2


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## mnclayshooter (Jul 5, 2016)

All of the searching and the help here made it pretty painless to get one ordered from Canon service/parts for less than $2.00.

Thanks! Here's hoping it doesn't spin me down the toilet of shame in attempting to replace it myself!

I figure worst-case scenario - I replace, it get some OOF images, and have to send it in anyways? 

I suppose: Truly worst case scenario... my camera body is somehow tied to global tectonic stability and undoing the screws that hold the spring in place somehow jar free the surface of the earth and send us all into a state of utter chaos... but with well-focused images to fully document it all. 

I feel like somewhere in the middle-ground is where I stand. A little risky, but maybe not that bad.


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## Mt Spokane Photography (Jul 5, 2016)

tolusina said:


> Mt Spokane Photography said:
> 
> 
> > The spring for the 5D *P/N is CS2-7205*. Its probably the same for all the camera bodies, but Canon could tell you. I did not see any variations in the parts catalog, the sensor has shims and the focus screen has shims, but none for the mount.
> ...



Yes, but that price is crazy. $31 plus $34 shipping for a 1/4 oz part?

$10 on ebay with free shipping.

http://www.ebay.com/itm/Canon-EOS-5D-Mark-II-Replacement-Lens-Mount-Spring-Free-Shipping-/301965239450?hash=item464e87e49a:g:dOgAAOSwnDZT951r

I expect Canon sells it for <$5.

Come to think of it, I've got a bunch of old film SLR's that I used to trade-in to the CLP. I'll bet they use the same spring. You can have one for just the postage if you want, I'll pull one off and send it to you.


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## mnclayshooter (Jul 5, 2016)

Mt Spokane Photography said:


> tolusina said:
> 
> 
> > Mt Spokane Photography said:
> ...



Thanks for the offer... I'll keep it in mind if my Plan-A/B ends up in Plan-C or Plan-D territory. I just got one ordered from Canon - they're backordered, no idea how long it will take to get one in stock, so, on second thought, maybe I should just get one from you! I'll PM you my info.


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## retroreflection (Jul 5, 2016)

Why did it fail? Fatigue - a failure mode where many cycles of loading and unloading at a stress less than the yield stress can lead to a crack. It is an unfortunate fact of life in engineered components. Springs are one class of components that face fatigue cracks all the time (fatigue softening as well, the reason old cars ride a tad lower).
The fact that replacements are sold indicates it is not an unusual failure. Canon probably had to push things to get a spring that fits in the allotted space and a mounting action that feels right. Then they assume a certain number of lens exchanges over the life of the body. Combine a microscopic manufacturing defect with a lens swapping, old body keeping shooter and you need to spend $10 or more.


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## mnclayshooter (Jul 5, 2016)

retroreflection said:


> Why did it fail? Fatigue - a failure mode where many cycles of loading and unloading at a stress less than the yield stress can lead to a crack. It is an unfortunate fact of life in engineered components. Springs are one class of components that face fatigue cracks all the time (fatigue softening as well, the reason old cars ride a tad lower).
> The fact that replacements are sold indicates it is not an unusual failure. Canon probably had to push things to get a spring that fits in the allotted space and a mounting action that feels right. Then they assume a certain number of lens exchanges over the life of the body. Combine a microscopic manufacturing defect with a lens swapping, old body keeping shooter and you need to spend $10 or more.



That's where my mind went too... fatigue is fatigue... I just don't think that I've put it through enough cycles of stress, that's all. I rarely changes lenses on that body. I only had one with over the weekend, thus, switched from a 100-400 to a 16-35 to catch the harbor view vs the approaching ships. I think a tiny mfr defect is probably the culprit... it's assuredly a mass-produced stamped piece that has to be deformed to get the spring tension capability. The deformation was probably not perfect. I'm going to take a lot closer look at it again tonight to see if I can see any obvious reason (maybe the 16-35 mount flange has a small defect/blemish that snagged the edge of the spring?... the 16-35 is about 2 weeks old - that's why my mind goes there).


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## Valvebounce (Jul 6, 2016)

Hi mnclayshooter. 
I'd say your luck was in with that failure, there are so many ways it could have gone, but on the bed spread is the last place it would go if it happened to me, my luck says it would have stayed in the mirror box and gone through the shutter and destroyed the sensor or dropped in to the rear of a lens and jammed the AF or IS modules. :
Good luck on your fix, I haven't seen the parts book, but a video I saw of tearing down a camera made note of the shimming and critical adjustment measurements on the sensor mounting points so I'd guess that the lens mount is fitted until the screws are tight type fit. Might be a different story if you were changing the mount ring for a new one due to manufacturing variations. It looks like the spring ring is cut away to clear the locations for mounting the lens mount, might be that it is a floating item so manufacturing tolerances will not affect the mount. 
Just had one thought, I would be wary of fitting lenses with it broken as it might tear in to the mount and introduce swarf to the mirror box. 

Cheers, Graham.


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## mnclayshooter (Jul 6, 2016)

Valvebounce said:


> Hi mnclayshooter.
> I'd say your luck was in with that failure, there are so many ways it could have gone, but on the bed spread is the last place it would go if it happened to me, my luck says it would have stayed in the mirror box and gone through the shutter and destroyed the sensor or dropped in to the rear of a lens and jammed the AF or IS modules. :
> Good luck on your fix, I haven't seen the parts book, but a video I saw of tearing down a camera made note of the shimming and critical adjustment measurements on the sensor mounting points so I'd guess that the lens mount is fitted until the screws are tight type fit. Might be a different story if you were changing the mount ring for a new one due to manufacturing variations. It looks like the spring ring is cut away to clear the locations for mounting the lens mount, might be that it is a floating item so manufacturing tolerances will not affect the mount.
> Just had one thought, I would be wary of fitting lenses with it broken as it might tear in to the mount and introduce swarf to the mirror box.
> ...



That's the same kind of luck I usually have. I look at it this way... at least I saw it. I might have gone on forever not knowing that it had even broken... how often do you inspect the inside of the mount and notice something like that!? 

That body is firmly placed on time out until I can get the spring issue resolved for exactly the reason you identified. No need to fill the sensor with metal bits.


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## Mt Spokane Photography (Jul 6, 2016)

Valvebounce said:


> Hi mnclayshooter.
> I'd say your luck was in with that failure, there are so many ways it could have gone, but on the bed spread is the last place it would go if it happened to me, my luck says it would have stayed in the mirror box and gone through the shutter and destroyed the sensor or dropped in to the rear of a lens and jammed the AF or IS modules. :
> Good luck on your fix, I haven't seen the parts book, but a video I saw of tearing down a camera made note of the shimming and critical adjustment measurements on the sensor mounting points so I'd guess that the lens mount is fitted until the screws are tight type fit. Might be a different story if you were changing the mount ring for a new one due to manufacturing variations. It looks like the spring ring is cut away to clear the locations for mounting the lens mount, might be that it is a floating item so manufacturing tolerances will not affect the mount.
> Just had one thought, I would be wary of fitting lenses with it broken as it might tear in to the mount and introduce swarf to the mirror box.
> ...



I went out and pulled the spring from a old T-50 SLR that I had kept in case I ever wanted to use the Canon Loyalty Program again to trade in towards a refurbished camera (It will still be a valid trade-in without its mount). The spring looks the same, but its hard to tell until its compared with the old one. It indeed floats, and does not affect tolerances. The T-50 had a brass shim under the plastic lens mount, but its not there on the DSLR's I've seen.

I'm sending it to Joe so he can see if its a match.


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## 3kramd5 (Jul 7, 2016)

mnclayshooter said:


> For clarity, the whole ring didn't come out - just the small tab circled, broke off.



Whew, I was going to start questioning my understanding of reality


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## mnclayshooter (Jul 16, 2016)

mnclayshooter said:


> Over this past weekend, I was photographing the ships coming into and out of Duluth Harbor and in my hotel room, I found a small tab of metal laying on the white comforter on the bed... right in the area where I had just changed a lens. I investigated a bit and found that one of the three equally spaced mount components circled in red have what appears to be a piece of spring steel (maybe a different metal or some alloy) behind it. The piece of metal on the bed matched up to those tabs (or at least half of one of those tabs).
> 
> My questions:
> 
> ...




Update: Thanks to Mt. Spokane and Canon for sending over springs so I could take a whack at this myself. I finally got a few minutes (about 120 of them to be exact... give or take?).. to tackle this. 

I found a pretty good step by-step dissassembly diagram/workflow online for a 6D... not sure if it's exacty the same for all bodies, but I imagine it would be. It worked for my purposes. I really just wanted a pointer or two on how/what order to disassemble the body and what to watch for as far as ribbon cables etc goes. It proved very helpful in that regard. here's a link for anyone feeling a little adventurous (or ready for one of the most nerve-wracking experiences you may ever encounter...https://www.ifixit.com/Guide/Canon+EOS+6D+Front+and+Top+Body+Panel+Replacement/25234 

You do, in fact have to follow all the way down to the bottom, taking literally every body panel off and something like 25 body screws to get it all apart to the point of getting access to the mount. That's where it all fell apart on me. I couldn't get the 4 mount screws out. I tried for a while... up until the point of starting to mar the head of the screw a little bit. Fearing irreparable damage, I stopped at that point, not ever getting the actual mount ring off. One word of advice... I stuffed a clean lens cloth in front of the mirror gently as a sort of "plug" to keep anything from falling into the mirror box, and had a body cap on there up until that point (or the point when the front panel has to come off at least. 

The spring has an additional screw on it that does appear to tie back to the electrical circuit below the lens mount. I can't quite tell what it is, but it looks pretty unsophisticated... like a ground connection. 

Anyhoo... thanks again for all of the words of advice. I think I tested the limit of my braveness... especially when a slip of my forceps sent a screw flying... thankfully I have a bunch of rare-earth magnets of pretty significant strength at my disposal... it snapped it right up out of the carpet without any trouble. 

It's all re-assembled, powers up correctly, snaps photos correctly. I'm done for today. Canon's turn to try.


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## Mt Spokane Photography (Jul 16, 2016)

Always use JIS screwdrivers, people think those screw heads are Phillips, but they are not. A Phillips screwdriver is likely to ruin the screw head for the lens mount.

That video calls for Phillips screwdrivers, its a huge error. After seeing that, I'd have zero confidence in anything they tell you.


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## mnclayshooter (Jul 18, 2016)

Mt Spokane Photography said:


> Always use JIS screwdrivers, people think those screw heads are Phillips, but they are not. A Phillips screwdriver is likely to ruin the screw head for the lens mount.
> 
> That video calls for Phillips screwdrivers, its a huge error. After seeing that, I'd have zero confidence in anything they tell you.



Thanks... good catch - I hadn't looked at his notes that closely... just the pictures of the steps and the description of what would be encountered. 

As to the disassembly - The mount screws weren't showing any signs of budging, so I stopped. I'm not sure if they have a thread locking compound on them maybe? I had no resistance on any of the body screws.


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## Mt Spokane Photography (Jul 18, 2016)

mnclayshooter said:


> Mt Spokane Photography said:
> 
> 
> > Always use JIS screwdrivers, people think those screw heads are Phillips, but they are not. A Phillips screwdriver is likely to ruin the screw head for the lens mount.
> ...



They do not want those screws to loosen, so they use screws that fit very tightly. Even with the correct JIS screwdriver, they are very difficult to loosen. With a Phillips, its almost certain that they will be damaged before coming out.

In the US, Moody makes some good JIS screwdrivers. Its a good idea for anyone who works with electronics to have a set or two. I have both short shaft and long shaft ones. Four piece sets run about $25 plus shipping. I have bought a lot of camera tools from Micro Tools.

http://www.micro-tools.com/product.htm?pid=132757&cat=15485


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