Les secrets du Canon RF 85 mm f/1.2 L USM

Le Canon RF 85 mm f/1.2 L USM dont nous parlions ici Le Canon RF 85 mm f/1.2 L USM annoncé), s’imposera probablement parmi les objectifs les plus incontournables de la décennie à venir…

De ce que j’ai déjà pu expérimenter de son petit frère le RF 50 mm f/1.2… Et de ce que je connais de son ancêtre le plus direct le EF 85 mm f/1.4 : je suis prêt à prendre les paris là-dessus. Aujourd’hui, vous pouvez découvrir un passionnant article qui dévoile les secrets de conception du Canon RF 85mm F1.2L USM.

Extrait :

« Why did you choose an f/1.2 aperture rather than f/1.4?

Satoshi: « Although one may think there isn’t much difference between f/1.2 and f/1.4 when just looking at the numbers, there is nearly a half stop of difference in brightness. Nearly 1.4 times more light is taken in, resulting in a whole new level in terms of design difficulty. A half stop difference may not seem like much, but when designing large aperture lenses such as f/1.2 and f/1.4, this half stop makes a huge difference in terms of difficulty of design. »

Kaishi: « The combination of stunning sharpness in the focused areas and the extremely shallow depth of field of f/1.2 delivers unmatched images. Portraits that use the shallow depth of field of f/1.2 have a unique beauty. The widest aperture setting on the RF 85mm F1.2L USM delivers a beautiful bokeh quality not found on other lenses, and amazing resolution, embodying a new type of imaging expression in portrait photography. That is why f/1.2 was chosen. »

 

Can the bokeh get any creamier?

Tomohiko: « The strong bokeh produced by the large aperture of the Canon RF 85mm F1.2L USM is one feature of the lens. However, lenses with significant chromatic aberration suppression tend to have slightly clearer bokeh contours.

« Some users aren’t fond of this clarity in the bokeh, for example when the leaves of a tree overlap in the defocused area. In this regard, we wanted to create a unique lens that delivers smoother bokeh quality, motivating us to start the development of the RF 85mm F1.2L USM DS with Defocus Smoothing (DS) coating. Although its specifications are basically the same as the Canon RF 85mm F1.2L USM, the DS coating will let users enjoy a softer bokeh quality. »

(…)

Is the autofocus up to the L-series lens standard?

Masami: « The Canon RF 85mm F1.2L USM lens uses the same ring-type ultrasonic motor (USM) as on the super telephoto lenses, which has the most powerful torque of any Canon lens, making focusing extremely fast despite the large optics. »

Yasushi: « Although the AF drive speed from close-up to infinity is approximately the same as on conventional models, including a focusing range distance selector switch reduces the focusing time during normal shooting, such as portraiture, for more comfortable usage. »

(…)

Why is the Canon RF 85mm f/1.2L USM longer than its EF mount counterpart?

Satoshi: « In terms of optical design, the total length is measured from the focal plane (the position of the imaging sensor or film). If you compare the EF and RF mounts, the lens mount is closer to the sensor on the RF mount than is the case with the EF mount. Because of this the EF version of some lenses can be shorter as the extra distance is taken up by the longer distance between the lens mount and the sensor in a DSLR camera. This naturally makes the RF version longer in total length to compensate for the difference in sensor-to-mount distance. An easier way to see this is comparing the size of the Canon RF 85mm F1.2L USM by itself and the Canon EF 85mm f/1.2L II USM with the Mount Adapter EF-EOS R attached. The difference is now smaller, and this is the difference you see when you mount the two lenses on the same Canon EOS R camera. »

Lire la suite…

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