Does The Canon RF 200-800mm f/6.3-9 IS USM Have A Design Weakness?

[SereneSpeed]

If it was metal then it would be either aluminium or magnesium which are both prone to cracking under stress

Airplanes and sailboat masts, also made of aluminum tube, show what properly engineered aluminum can withstand. Aluminum work hardens (creating the conditions for “cracking under stress”) only after exceeding elastic deformation limits - poor engineering.

For a 12” tube, 3” diameter, aluminum can be 1/16” wall thickness, with PEEK (high-grade plastic) having to be 3/16” to have the same load capacity before yielding. However, a solid PEEK rod, 3” diameter, has 35% the stiffness of the aluminum tube (deflects more under the same load). There’s no wall thickness at that diameter that comes close to matching aluminum.

I have no idea what Canon uses. I just grabbed 6061 aluminum and PEEK from thin air…

There are definitely benefits to each, but aluminum is likely better suited for a lens, when durability is the goal.

I don’t know much about magnesium and don’t want to do the math

 

[emc]

Why ask? This lens clearly has a design weakness. The material must not be strong enough. But if this is confirmed, the corrected version will cost a little more, and may be upgraded to L-version as a result.

 

[AlanF]

Why ask? This lens clearly has a design weakness. The material must not be strong enough. But if this is confirmed, the corrected version will cost a little more, and may be upgraded to L-version as a result.

It won't be upgraded to an L. It's not an L for many factors. It lacks fluorine coatings, the white paint is not the IR-relective coating as used on L lenses, it has fewer controls on the lens, only one AF motor and some cheaper glass. The weakness of the lens to breakage would not have been anticipated by Canon who now have the expense of repairing these under warranty in general and for a much longer period in countries where manufacturers are responsible for correcting design faults beyond warranty periods.

 

[neuroanatomist]

Why ask? This lens clearly has a design weakness. The material must not be strong enough. But if this is confirmed, the corrected version will cost a little more, and may be upgraded to L-version as a result.

The 'correction' would be an unannounced design change to new batches of the lens. They're not going to develop and launch an 200-800L to 'fix' the problem. If the failure is pervasive enough, they'll develop a fix that can be applied to existing lenses (e.g., replacing a weak component with a stronger one) and recall/repair the affected lenses.

Also, why do you assume it was a design weakness? That's certainly possible, but it's also quite possible that one of the components suffered from a manufacturing flaw, e.g. the alloy for a metal part was not as specified or a 'plastic' part was not properly cured to design specification. In that case, it may only be specific batches of the lens that used the affected part that are failing. If so, Canon will issue a recall for a range of lens serial numbers (again, if the problem is pervasive enough).

 

[docsmith]

That's certainly possible, but it's also quite possible that one of the components suffered from a manufacturing flaw, e.g. the alloy for a metal part was not as specified or a 'plastic' part was not properly cured to design specification. In that case, it may only be specific batches of the lens that used the affected part that are failing. If so, Canon will issue a recall for a range of lens serial numbers (again, if the problem is pervasive enough).

This is a good thought and may explain why some of us have traveled/used this lens extensively without issue while others have had an issue doing the same activities.

As for me, I have traveled with my copy by air around 4 trips (total of ~12 flights). It has also been my go-to lens for local birding trips. I've had it in parks and out on a kayak 8-12 times each.

 

[Chig]

Mine hasn't broken in half (yet), but I'm disappointed with the sharpness. My 100-400mm MK2 and 1.4X MK3 combo is sharper at every zoom level.

And of course, my 500mm with the 1.4 X is sharper too. But that thing is a beast to carry.

I guess I'm just spoiled by the L glass.

I found my 200-800 much sharper than my 100-400 ii with or without extenders and it was just as sharp as my EF 400 f/2.8 and 300 f/2.8 so I sold all 3 lenses

 

[David_B]

Just like the R7, it was built to a price point and had to make sacrifices that I’m not fond of.

This lens hasn't been built to a price point, it is design failure.

 

[David_B]

I keep wondering how much more expensive a metal assembly flange would have been.
We all know such a lens must be able to take some abuse (safaris, for instance).
Sorry, but for me this is poor engineering, unless only a small batch is affected.
Most lenses made by Canon are extremely well designed mechanically, as often stated by Roger Cicala. What went wrong here?

This is my feeling too. Maybe they need the equivalent of reo for concrete in the plastic but I don't know if that helps or hinders, surely smarter people than I would have answered that. Meaning it doesn't need to be a full aluminum build but maybe a dozen or so aluminmum segments in the plastic to give it more strength because there's very obviously a weak point in the barrel design.

I don't know about "bad batches", maybe serial number ID'ing of failed lenses would highlight that.

But for the guy in Svalbard, I can easily see being in cold temperatures increasing the brittleness of the lens's plastic leading to it failing unexpectedly.

 

[David_B]

There certainly is copy variation. I have compared two copies of the RF 200-800mm. One was noticeably sharper than the other on the R5 at both 500mm and 800mm. The sharper copy is as sharp as the RF 100-500mm at 500mm, or even slightly sharper. It is certainly sharper than the RF 100-500mm + 1.4xTC.

I would have thought that micro focus adjust plus sensor based focusing would have almost eliminated any "soft" lens issues.

 

[neuroanatomist]

I would have thought that micro focus adjust plus sensor based focusing would have almost eliminated any "soft" lens issues.

I would’ve thought you’d learned to not weigh in on technical discussions. Featherweight thinking doesn’t tip a scale.

 

[AlanF]

I would have thought that micro focus adjust plus sensor based focusing would have almost eliminated any "soft" lens issues.

Canon mirrorless do not have AF micro adjustments and, in any case, lens softness is caused by optical aberrations not AF in these circumstances.

 

[justaCanonuser]

Many, many thanks for this report about mechanical failures. I really need to be careful with that lens, I see. My now 30 years old EF 500mm is really battered and survived some heavy accidents in the wilderness but still works. I did not expect the RF 200-800 to be as solid as an L lens, but that is an additional warning to be careful.

In fact, I like the RF 200-800, and I can't complain about the sharpness of my copy. It doesn't match my EF 600mm f/4 III that is currently my main birding lens, but that's another league - and a prime lens. For such an enormous zoom range the RF200-800 performs quite well - much better than I expected when I ordered it.

 

[EJBart3791]

I had the exact same break happen while sitting on a game vehicle waiting to head out on a game drive. Lens was just over 4-6 months old! Luckily, I had my 100-500mm as a back-up! Canon SA said this was the first \"break\" that had been reported. Their investigation stated that it was due to a extreme external force/ impact that caused this. Had I dropped it, I would not have been upset, as accidents happen. However, I still feel this is not the case! Canon SA distanced themselves, and I eventually had to pay for the repairs.
Great lens that works well on my R5 mki, R5mkii and expecially on my R7 (with the extra 1,6x reach) for bird photography. Would be interested to join a register to see how many have had this similar \"snap\" experience??

 

[justaCanonuser]

There certainly is copy variation. I have compared two copies of the RF 200-800mm. One was noticeably sharper than the other on the R5 at both 500mm and 800mm. The sharper copy is as sharp as the RF 100-500mm at 500mm, or even slightly sharper. It is certainly sharper than the RF 100-500mm + 1.4xTC.

Thanks, that explains why there are so different experiences with sharpness reported in this thread. I obviously am lucky to have a quite sharp copy (at the long end, which is most important for birders). Canon is well-known for their very sophisticated control of correctly adjusted lens groups etc. So they gained a very steady quality in the past decade, but that applies to their domestic production in Japan. Maybe the quality control of their production in Tawain still needs to be improved.

 

[AlanF]

Thanks, that explains why there are so different experiences with sharpness reported in this thread. I obviously am lucky to have a quite sharp copy (at the long end, which is most important for birders). Canon is well-known for their very sophisticated control of correctly adjusted lens groups etc. So they gained a very steady quality in the past decade, but that applies to their domestic production in Japan. Maybe the quality control of their production in Tawain still needs to be improved.

You can see my images in the Bird Portraits thread and the Birds in Flight. I am more than happy with their sharpness. So much so that if the end falls off I’ll glue it back rather than send it to Canon.

 

[Del Paso]

Airplanes and sailboat masts, also made of aluminum tube, show what properly engineered aluminum can withstand. Aluminum work hardens (creating the conditions for “cracking under stress”) only after exceeding elastic deformation limits - poor engineering.

For a 12” tube, 3” diameter, aluminum can be 1/16” wall thickness, with PEEK (high-grade plastic) having to be 3/16” to have the same load capacity before yielding. However, a solid PEEK rod, 3” diameter, has 35% the stiffness of the aluminum tube (deflects more under the same load). There’s no wall thickness at that diameter that comes close to matching aluminum.

I have no idea what Canon uses. I just grabbed 6061 aluminum and PEEK from thin air…

There are definitely benefits to each, but aluminum is likely better suited for a lens, when durability is the goal.

I don’t know much about magnesium and don’t want to do the math

Agreed!
If you look at downhill bike frames, they are often made of aluminium (6061 or expensive 7005 for Nicolai...) depending on the price tag and hardening process. And these bikes take an enormous amount of beating (ask my son...). Handlebars too (extremely safety relevant!) are often made of aluminium, and quality products almost never break unless poorly mounted.
When plastics are used, then exclusively carbon-fiber reinforced. But they are submitted to a different type of stress compared to a lens flange...
Aluminium is soft, alloys aren't. You'll easily notice it when you shorten a handlebar. As a link between two lens' halves? Aluminium, without hesitating a fraction of a second!

 

[bird photo nerd]

I thought the title might be referring to the lens foot. When I bought my $2400 100-500mm, the first thing I had to do was remove that worthless lens foot and spend another $40 or whatever it was on an Arca compatible one.

On the 200-800 it's not only not Arca compatible, it's not removable! Why, Canon? Why?

 

[neuroanatomist]

I thought the title might be referring to the lens foot. When I bought my $2400 100-500mm, the first thing I had to do was remove that worthless lens foot and spend another $40 or whatever it was on an Arca compatible one.

On the 200-800 it's not only not Arca compatible, it's not removable! Why, Canon? Why?

For one thing, putting a dovetail on the foot would add thickness. For another, there are other brands of quick-release support systems (e.g. Manfrotto). I'd personally like them to include it, but I get why they don't. The non-removable foot/collar on the 200-800 is probably a cost-saving rationale.

 

[David_B]

Don't feed the troll.

 

[David_B]

Thanks, that explains why there are so different experiences with sharpness reported in this thread. I obviously am lucky to have a quite sharp copy (at the long end, which is most important for birders). Canon is well-known for their very sophisticated control of correctly adjusted lens groups etc. So they gained a very steady quality in the past decade, but that applies to their domestic production in Japan. Maybe the quality control of their production in Tawain still needs to be improved.

If you have a copy where you suspect the lens isn't sharp, a trip via the post to Canon's camera/lens service can usually resolve that. Don't know if they'll do it under warranty for free.