if the optical aberations come from misaligned elements then that can be corrected but if they're a result of variation in the manufacturing of the lens elements I don't know how they fix that... well, just add some extra "post" processing to their firmware.
The problem is that manufacturers can have specifications that span the ranges which we consider not to be sharp. I once sent back a soft 100-400mm lens to Tamron and it was returned as being within specs.
I seriously am thinking of purchasing a piece of plastic pipe with a bit bigger diameter than the 200-800, cut it at the right length for the collapsed zoom, cut it in two half shells with a hole for the tripod foot and pad it softly inside. This would make a quite solid protective case that still would fit in my backpacks. Then I would be prepared for really rugged environments. That said, so far my zoom survived already trips on which it wasn't exactly pampered. I even fell on my backpack carrying this zoom when I stumbled over a hidden hole in a mudflat.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.
Although I joked earlier about carrying some quick-set epoxy resin, the two surfaces where the break occurred look like a perfect fit for glueing and it would work in an emergency to give a very strong bond.
Or a break-up?
I remember that the first generation 70-200 f/2.8 Sony zoom had nearly the same problem, but this lens didn't break into two pieces, it bended like a banana (somewhat exaggerated described). LensRentals found during a tear-down that the engineers used a connection ring between the front and back piece that was made of a too soft metal alloy. In contrast to Canon, this Sony lens was sold as a pro grade lens, so it should have been more rugged (Sony improved the next generation, of course).
Hey, you are one of the rare EF 800 f/5.6 owners! I have seen so many different superteles in the field, meeting other birders, but never anyone carrying that beast of a lens with her or him. Interesting what you tell about the 200-800 + R7 combo! I have exactly the same experience, so obviously we both are lucky owners of a sharp copy. It is a real fun combo that can produce stunningly sharp results for a zoom lens. But my EF 600mm f/4.0 Mk III + 1.4 TC Mk III (effectively 840mm f/5.6) with the R7 is sharper. The difference is not immediately obvious, but is noticeable when zooming into the details of the image files (feather structures e.g.).
It is definitely a design flaw, because Canon's engineers should have considered that e.g. an extended 200-800 is a quite long lens. So, mechanically you get a long lever, which accordingly increases the forces in this ring that connects the two parts of this lens. But metal is not per se a remedy. If such a ring is made of too soft alloy it replaces breaking by bending like a banana (exaggerated), Sony users had to learn with the 1st generation of Sony's 70-200mm f/2.8:
Sure, a design flaw, and they didn't learn from what happened to Sony...You cannot fool physics.It is definitely a design flaw, because Canon's engineers should have considered that e.g. an extended 200-800 is a quite long lens. So, mechanically you get a long lever, which accordingly increases the forces in this ring that connects the two parts of this lens. But metal is not per se a remedy. If such a ring is made of too soft alloy it replaces breaking by bending like a banana (exaggerated), Sony users had to learn with the 1st generation of Sony's 70-200mm f/2.8:
Completing the Teardown of the Sony FE 70-200 f/2.8 GM OSS: Part II
You probably shouldn't read this article unless you've at least skimmed through Part 1. To summarize, we had a Sony FE 70-200mm f/2.8 GM OSS lens that had been dropped and no longer would focus. We tore it down both to see if we could repair it and to see what-all was up inside there. In the [...]www.lensrentals.com
That said, I think it wouldn't cost Canon a fortune of investment to replace that critical plastic part by a sufficiently strong metal ring. I guess they'll do that latest with the Mk II version or maybe with the actual generation to avoid too many repairs - and a loss of reputation of that bestseller of a lens.
If that happens too often, it might be cheaper to replace this plastic connector ring with a metal ring during the production of the Mk I version.
They have to - goods have to be fit for use and, in any case, we are well within the warranty period for most of these lenses.
The EF 800 f/5.6 L is an interesting lens. The front piece of glass is just a flat protective window and the first real element is a full diameter fluorite lens. I think the 800 compares petty equally to the 600 II and 600 III at similar focal lengths. In theory, it will have slightly less resolving power than the 600s due to having a slightly smaller objective. 600/4 = 150mm. 800/5.6 = 142.9mm and that is not a huge difference, but maybe enough to be noticeably by some. They guy I bought the 800 from also had an EF 600 II and he thought it was slightly sharper with extenders. The main advantage of the EF III/RF teles is the change in design that moves the fluorite elements further back in the lens so they are much smaller. They are lighter and better balanced from a user perspective, but also very likely much cheaper to manufacture, albeit that is not reflected in the price
,I believe that was also the case with the mark I EF 500 and 600 lenses, removing the protective front (non-optical) element is one way they saved weight on the mark II versions.
Yes the first gen had the flat glass. The 800 and 600 II have the biggest fluorite elements. The flat glass is nice from a scratch repair perspective and in the case of the 800 essential, because you can't expose a fluorite element to the outside world.
That's Canon's old L supertele design, I have an EF 500mm f/4.5 L USM from 1995 that was my main tele prime until this year. It has a protective front glass window, too, and I think the 2nd optical element is a fluorite glass lens. I loved this quite handy lens and never missed IS - or only when doing video from a tripod in windy conditions, because its long hood then caused small but visible vibrations. But now, after 30 years of heavy use (I bought it used about 15 years ago) its mount is worn off - otherwise it still works (it survived quite a lot heavy accidents and severe wether conditions in the wilderness). So I took this year a plunge and bought a used EF 600mm f/4.0 III lens. That was of course an upgrade worth the investment. In particular, the 1st gen. USM drive was quite slow compared with modern superteles - but I was so used to the vintage 500 that I could catch good shots with it, even paired with Canon's 1.4x III TC. Here is one with 700mm, purple herons are of course an easy target, but this one was flying nearly towards me (but the 5D IV's AF system was good enough to catch the bird sharply, image slightly cropped):
Looking at the (theoretical) MTF charts, the EF 600 II is in the center slightly sharper (if you get a well-centered copy) than the 600 III (see e.g. Bryan Carnathan's very thorough review: https://www.canonrumors.com/forum/t...e-a-design-weakness.44456/page-6#post-1026367). I read somewhere that the 600 II and III + Canon's 1.4x TC III or the new RF TC also beat the 800/5.6 in sharpness @ f = 5.6. But I guess that in real life the difference wouldn't barely be noticeable, since the 800 features a modern lens design, too, and supertele shooting is much more impaired by atmospheric conditions than by optical limits today. Do you have a backpack in which that beast of lens fits? I guess Lowe's Lens Trekker III would swallow it... or do you use it only in a car or tear it behind you on a trolley?
For me it was a no brainer to prefer the 600 III over the II, because the about 800 g less weight and better balanced mass distribution over the length of the lens is much more important for me. I shoot such lenses mostly free hand, and 3 kg (+ camera) is a weight I still can handle when shooting BIF for a while, even with the quite light 1.4x TC added it is still quite light. Compared to the vintage 500/4.5, I had to get used to the much wider diameter of the 600, but thanks to Canon's latest design it is much less front-heavy than the old lens. I am not sure whether the production of the 600 III is so much cheaper than of the generations before: the expensive fluorite elements are much smaller, that's true, but the new design required an innovative extremely thin super UD element and an extremely big aperture (see Bryan Carnathan's review). Btw: Sony basically copied Canon's latest design in its current 600mm f/4 and achieved 10 (or so) g less weight for market their lens as the lightest 600/4 on the market, Nikon fell behind with their still 3.8 kg and more front-heavy 600/4 f mount - but they came up with their gorgeous light 600/6.3 for their Z mount, very smart.The main advantage of the EF III/RF teles is the change in design that moves the fluorite elements further back in the lens so they are much smaller. They are lighter and better balanced from a user perspective, but also very likely much cheaper to manufacture, albeit that is not reflected in the price
