400 2.8 IS II so light but so fragile

Started Feb 16, 2012 | Discussions
nedfr
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400 2.8 IS II so light but so fragile
Feb 16, 2012

Some inconvenience found by a 1 month new owner in Europe of this new 400 2.8 IS II. Regular/ normal use said.

Canon says at the moment : no warranty on lens hood, repair only (4 weeks delay minimum ...)

That sound hard to hear for a $10500 lens ...

http://www.hostingpics.net/viewer.php?id=226274342I2148.jpg

Apewithacamera
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 16, 2012

nedfr wrote:

Some inconvenience found by a 1 month new owner in Europe of this new 400 2.8 IS II. Regular/ normal use said.

Canon says at the moment : no warranty on lens hood, repair only (4 weeks delay minimum ...)

That sound hard to hear for a $10500 lens ...

http://www.hostingpics.net/viewer.php?id=226274342I2148.jpg

What's normal use? Banging the lens into a tree or something?

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nedfr
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Re: 400 2.8 IS II so light but so fragile
In reply to Apewithacamera, Feb 16, 2012

Don't know what normal use is for this canon owner.

My question was the new lens hood is perhaps a bit to light with weakness at this point.

Any feedback from 300' 400' IS II owners ?

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Apewithacamera
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 16, 2012

There is a small black mark on the knob itself maybe that is where the impact occurred.
Is it a weakness of the lens hood? It could very well be.

Regards

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The_cheshirecat
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Re: 400 2.8 IS II so light but so fragile
In reply to Apewithacamera, Feb 16, 2012

The knob looks somewhat deformed where the black mark is. If so, that was likely quite a hit it took there.
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NCal-Cyclist
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 16, 2012

I have a 400/2.8 IS II that I used for the last half of my sons HS football season last fall....the last game, I managed to drop the hood onto CONCRETE (just missed the rubberized track surface). No cracks, or chips - just a VERY MINOR scuff - though mine didn't strike the tensioner screw.

Just my experience with a great lens...

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Peter White
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 16, 2012

Such an abrupt reinforcement around the screw creates a stress riser. It's a poor design.

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nedfr
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Re: 400 2.8 IS II so light but so fragile
In reply to Peter White, Feb 16, 2012

Just made this design comparaison pic.

A design flaw ?

http://www.hostingpics.net/viewer.php?id=708663400V1V2.jpg

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Jim4496
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 16, 2012

Unless you can provide information about how the cracks developed its hard to say if it is a design flaw or just carelessness on the part of the owner.

The signs point to the lens having been dropped on the knob. Or at the very least the knob was banged into something.

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Peter White
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Re: 400 2.8 IS II so light but so fragile
In reply to Jim4496, Feb 16, 2012

The crack is right at the transition between the thick section holding the screw and the rest of the hood. If that thick section were tapered down the hood may not have cracked. The transition to one thickness to the other thickness is the stress riser. Stress risers are always bad, except when you want something to break easily.

Imaging a piece of lumber, a 2x4 that's 8 feet long. Support it by both ends and put a 200 lb weight in the center. The board will bend but not break. Do the same with a board that's 2x2. It still doesn't break. Now take the 2x4 and reduce one half of the length to a 2x2. So now it's 4 feet long at 2x4 and 4 feet long at 2x2. Support it at both ends and put on the weight in the center. It will break right at the transition from 2x2 to 2x4. The transition is the stress riser. If you tapered the board from 2x4 to 2x2, it would bend, but not break.

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jimi_astroman
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Re: 400 2.8 IS II so light but so fragile
In reply to Peter White, Feb 17, 2012

The new mark II lens is as solid as the previous model but it won't take being banged off something hard or dropped - no lens will. The lens hood is made from carbon fibre - same as the old model. This isn't a warranty repair because it's clearly abuse (in whatever form that happened). If the photographer has the lens insured against all risks then claim on the insurance for accidental damage.
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PowderMaggot
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Re: 400 2.8 IS II so light but so fragile
In reply to nedfr, Feb 17, 2012

Your "friend" needs to say how it happened.

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nedfr
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Re: 400 2.8 IS II so light but so fragile
In reply to PowderMaggot, Feb 17, 2012

Update : He finally manage to contact a manager at Canon CPS France and the lens hood will be replace under warranty.

Delay for this replacement as not been said.

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Jim4496
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Re: 400 2.8 IS II so light but so fragile
In reply to Peter White, Feb 17, 2012

I actually understand what a stress riser is. It is not necessarily a design flaw. it just indicates the point at which failure is most likely to occur for a given applied stress. So my point is how much stress was it necessary to apply to cause the failure? If it was caused by normal use, ie tightening the screw then its a design flaw. If it was caused by dropping the lens on the knob, as the picture appears to indicate then it was abuse.

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scorrpio
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Re: 400 2.8 IS II so light but so fragile
In reply to Peter White, Feb 17, 2012

Peter White wrote:

The crack is right at the transition between the thick section holding the screw and the rest of the hood. If that thick section were tapered down the hood may not have cracked. The transition to one thickness to the other thickness is the stress riser. Stress risers are always bad, except when you want something to break easily.

What would have cracked if the hood didn't? Would the retaining screw deform the lens front? Or crack the front element?

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Apewithacamera
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Re: 400 2.8 IS II so light but so fragile
In reply to scorrpio, Feb 18, 2012

scorrpio wrote:

What would have cracked if the hood didn't? Would the retaining screw deform the lens front? Or crack the front element?

I still suspect that nob was the point of impact. I don't think the design of the new hoods is all that different than the previous super telephoto lens hoods. IDK if you have seen how these hoods attach but they have an internal ring that seats into a groove around the front of these lenses. That retaining screw just keeps the hoods in that grove.

I doubt any further damage could be done because the metal of the lens is quite substantial IMO.

I'm not going to whack my lenses into a tree to find out either.

These hoods are not cheap to replace.

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Montana500
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1 year warranty on a $10,000 lens is inexcusable
In reply to Peter White, Feb 18, 2012

Shame on canon for not covering the hood, either. Cheap.

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time20n
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Re: 1 year warranty on a $10,000 lens is inexcusable
In reply to Montana500, Feb 18, 2012

Cheap, or pretty smart of them no ???
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Yargo
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Re: 1 year warranty on a $10,000 lens is inexcusable
In reply to time20n, Feb 18, 2012

I can't see how the stress raiser can be negated , as it is clearly an insert of some kind and not part of the main casting/tube .

Looking at how the insert is pushed outwards , it may have been overtightened then the hood took a knock for the final blow .

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Apewithacamera
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How tight do others turn the lens hood nob?
In reply to Yargo, Feb 18, 2012

IDK if it is possible if damage could occur if all of the thread on the screw was used up. Maybe someone could chime in on that? When I tighten the nob I go until I just start to feel resistance then I go one half turn more and that's it.

Regards

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