Ever wondered how strong your lens mount is?

"Run Forrest, Run"

That takes quite a lot of load cycles to develop. The stress here is probably higher in relation to max allowed load, so it's more snapping that fatigue to worry about.

Or so I presume.

apersson850 wrote in post #17141696
That takes quite a lot of load cycles to develop. The stress here is probably higher in relation to max allowed load, so it's more snapping that fatigue to worry about.

Or so I presume.

I would think any fatigue would come from how the camera+lens is held when walking around with it.

A magnesium frame means aluminum-magnesium alloy. And aluminum has big issues with fatigue, since it doesn't have any fatigue limit - which is the reason why aluminum bike frames have so very big tube diameters to make them stiff enough to reduce how much they bend. And a reason why modern plane frames can only support a limited number of flight hours, while the old planes using steel can continue to fly as long as they get serviced.

Walking around with a lens like that you would hold it by the lens and not by the camera. If the lens mount would be still attached I would carry it by the lens mount as that makes an easy handle to carry.
The only time the full weight of the lens would be on the mount is when mounted as shown in the Op image. And I would never do that...

Gravity will have it's way sooner or later.

vk2gwk wrote in post #17141750
Walking around with a lens like that you would hold it by the lens and not by the camera. If the lens mount would be still attached I would carry it by the lens mount as that makes an easy handle to carry.
The only time the full weight of the lens would be on the mount is when mounted as shown in the Op image. And I would never do that...

Lots of people store the camera vertically standing on the lens. Then it's also natural to pick it up by lifting in the body.

My understanding is the 5mkiii mount is screwed into the plastic mirrorbox and is not supported by metal.

James

jbarber wrote in post #17142459
My understanding is the 5mkiii mount is screwed into the plastic mirrorbox and is not supported by metal.

James

in between is the magnesium alloy frame -||-|-|||| (- =screw passing thru, || =mount, | =magnesium frame, |||| = mirrorbox), in my understanding

OK it didnt sheer off - but I wouldn't be surprised if you ruined the tolerances of the lens being 90 degrees to the sensor!

The perfect example of why to buy new!

You guys are way too paranoid, these cameras aren't made of cardboard

panicatnabisco wrote in post #17145228
You guys are way too paranoid, these cameras aren't made of cardboard

No kidding.
I routinely have a 300 f2.8is or a Sigma 120-300os lens hanging off the camera while I'm walking around, hanging onto the grip.
I've done this with a 30D, 7D, T3i, 5DMKII and a 70D. Guess what, no problems.