IBIS Fractures ? Is that a thing ?

Started 3 months ago | Discussions thread
57even Forum Pro • Posts: 14,783
Re: Not really an issue for most users, IMHO
3

Antisthenes wrote:

57even wrote:

Antisthenes wrote:

57even wrote:

Antisthenes wrote:

The above is, of course, pure speculation of my part, only based on my observation of some long-time Nikon camera users, but I have no otherwise reasonable explanation about the origin of mechanical stresses sufficient to crack the (not that critical) supporting / spacer attachments between a body shell and a mount+sensor block.

You could always look it up...

https://petapixel.com/2020/06/12/lensrentals-flange-test-reveals-ibis-fractures-in-some-sony-cameras/

My experience of Sony cameras, though indirectly via some friends who traded Canon and Nikon DSLRs for Sony A series cameras, is that they are not as robust. Weak lens mounts was one example. This seems to be another.

Any vibrating system, especially one with any mass to it, is susceptible to stress fractures if not properly engineered.

I have had one camera replaced because an IBIS unit was faulty on purchase. When enabled, every image had noticeable motion blur and the sensor became increasingly misaligned with the camera.

When repaired, the camera only smeared images at 1/30, 1/60 and 1/120 of a second.

In case it's not clear, I have actually read the article you linked to.

In case it's not actually clear, I also trust my level of actual experience and understanding of physics and engineering issues more than, say, LensRentals'.

And your 'understanding' of engineering and physics leads to conclude that it's all down to ham-fisted Nikon users? Very scientific of you.

<<Patronising rant deleted for brevity>>

It's thus pure speculation of my part that twisting torque between the body shell and the lens mount caused by, say, human muscles might be involved, but it's not entirely illogical to consider, when trying to determine what might cause a linkage element to fracture, the origins and respective magnitudes of the forces that might be exerted on said elements.

For one thing, anyone twisting a lens hard enough to distort the body would almost certainly damage the lens mount and cause other issues, but that was not stated as a co-factor. In fact, fewer had mount issues than IBIS fractures.

Secondly, if you'd bothered to read further...

https://www.lensrentals.com/blog/2020/06/the-great-flange-to-sensor-distance-article-part-ii-photo-cameras/

You'd see that the fractured component was a plastic plate to which the sensor is mounted, which I would interpret to mean that it's part of the floating assembly, not the one mounted to the body. Hard to tell from these, but its clearly shown here...

https://www.youtube.com/watch?time_continue=8&v=-Ncye37e6xM&feature=emb_logo

In which case, it is part of the floating assembly and should be immune to torque stress on the rest of the body. And I'd like to see your muscles bend the cast metal parts of the IBIS assembly that it's mounted to.

I have no idea what the root cause is, but cracks in a plastic mounting may be due to misaligned holes, over-tightened screws, poor materials quality, or any number of things, which could lead to stress fractures developing.

And as for the forces involved, normally it would seem unlikely, but the plastic used appears quite brittle from the fracture line, so if a fault line was created during the assembly, it's not inconceivable that it would widen with movement and lead to failure. It's also possible it came from the factory like that.

The fact that a screw had actually sheared in one example does rather suggest an assembly error.

Perhaps you should look up Cognitive Dissonance and ask yourself why you are trying so hard to deny that it's a problem with (some) cameras and not with ham-fisted users.

And as for your kind lecture on high school physics, I have seen vibration stress in similar systems. Engineers seldom build anything stronger than it needs to be, and sometimes don't account for assembly variation, but if the system reaches the full extent of it's travel for any reason, the acceleration component at the bump stop can be quite high.

F = ma, which of course you know.

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"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." Antoine de Saint-Exupery

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