In an interview, Canon engineers tell how it came Canon made the RF 800mm f/11 and RF 600mm f/11 lenses. And what inspired them.
In an interview with DC Watch, Canon engineers tell the reasons and challenges in designing the RF 800mm f/11 and RF 600mm f/11 lenses. It seems, a boyhood experience of one of the engineers was one of the reasons (machine translated):
Iezuka: I’m sorry about my boyhood story. At that time, I wanted to take a picture of a wild bird, Little Egret, but I couldn’t buy a super-telephoto lens because it was too expensive. I tried to make a telephoto lens with a close-up lens with a focal length of 400 mm, but it didn’t look good, and I wondered why it didn’t look so good.
I knew that there were many people who gave up what they wanted to shoot and the expressions they wanted to shoot because they couldn’t buy a super-telephoto lens and couldn’t carry it because it was big and heavy.
Canon already made a similar lens in 1960, the R 1000mm f/11:
Looking back, Canon’s first SLR camera system, the R mount (1959-), also had a “slender” super-telephoto lens like the 600mm / 800mm F11. The optical system is as simple as a telescope, the focusing is bellows, and the weight is as light as 2 kg.
The Canon R 1000 f/11
Why f/11?
Iezuka: Since the EOS R system can measure distances up to the maximum aperture of F22, I thought that the F value of the lens alone would be F11, considering the installation of a 2x extender. With F8, the lens becomes thicker, and with F16, it exceeds F22 when the 2x extender is attached. Around this time, the idea of ”Why don’t you eliminate the aperture unit for F11?”
I understood that there is a need to reduce the shutter speed further from F11 when considering panning at super telephoto, but control of the depth of field is less important at super telephoto, and it is low. The aperture unit was not installed because it leads to cost reduction and weight reduction.
Whaaaat? a f/11 lens with 800m? Kidding? Read this Canon RF 800mm f/11 IS STM review and you might get surprised.
At a glance:
RF-Mount Lens/Full-Frame Format
Fixed f/11 Aperture
Retractable, Locking Lens Barrel
Gapless Dual-Layer Diffractive Optics
The RF 800mm seems to be the world’s lightest 800mm telephoto lens. That’s possibile because of the fixed f/11 setting. Photography Blog posted their Canon RF 800mm f/11 IS STM review. From their conclusion:
[…] there’s no getting away from that fixed f/11 aperture which limits its use to either bright conditions or high ISO speeds (or sometimes both), the lack of any kind of weather-sealing at all may well put off more hard-core users, the 6m minimum focusing distance is a little restrictive, the tripod mount can’t be rotated from landscape to portrait position, there could be some question marks over the long-term durability of the retractable design, and the essential lens hood is unfortunately an expensive optional accessory.
All in all, though, the Canon RF 800mm F11 IS STM is a refreshingly brave attempt to make an otherwise expensive branch of photography more accessible, both in terms of cost and portability – there simply aren’t any other 800mm lenses that are as inexpensive, compact and crucially as good as this one. Bravo to Canon for thinking out of the box.
A Canon patent application (2018-087965) for what might be the future replacement for the Canon EF 800mm f/5.6L IS lens.
The patent literature describes a lens concept where weight and size are reduced without affecting optical performance or causing increased chromatic aberrations.
Machine translated patent literature excerpt:
The method of using for a part of imaging optical system the diffracted-light faculty which has a diffraction working effect as a method of reducing lens weight is known correcting satisfactorily several aberration including the chromatic aberration of the imaging optical system. The imaging optical system which constituted the front lens group from ** material whose refractive index is higher than a low dispersing material with abnormal portion dispersibility, such as fluorite, and attained size and weight reduction of the whole system is known, using a diffraction working effect and reducing the lens number of sheets of the front lens group which was conventionally required for aberration compensation
There is a lot of buzz around Canon patent applications as of lately, and a lot of misunderstanding too. Bear in mind that a patent application does not mean a company will launch a product anytime soon. A patent application is a way companies have to secure their research and their intellectual property. In this sense, nothing here is a guarantee that the EF 800mm f/5.6L lens will be replaced in the close future.
Some Canon patent applications we think might get into production in the next few years are these:
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