Canon Gets 300mm Creative

[Richard CR]

We have an interesting patent application (2026-004766) for you today. This is a patent for a Canon RF 300mm f/2.L IS USM. Now, as we have discussed previously, the 300mm f/2.8 is still noticeably missing, and while we lust for a Canon RF 300mm f2L IS USM, maybe the world needs a more affordable Canon […]

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[Tom Raymond]

In 1981, Nikon made a few 300mm F2.0 lenses. Manual focus of course. I have seen pictures of these beasts, I think weighing in at over 15 pounds.

 

[juststeve]

Given the compact appearance of this lens, could this be a diffractive optics lens? Lens length from front element to rear filter looks to be about 250 mm, allowing for a front element of 112 mm and my use of dial calipers to approximate length (questionable, perhaps). And notice the ragged elements drawn in note GP. DO indicators? Nikon has been doing well it seems with its diffractive optics telephotos. Maybe Canon, the pioneer, is wanting to show folks just how to do it.

 

[neuroanatomist]

Given the compact appearance of this lens, could this be a diffractive optics lens? Lens length from front element to rear filter looks to be about 250 mm, allowing for a front element of 112 mm and my use of dial calipers to approximate length (questionable, perhaps). And notice the ragged elements drawn in note GP. DO indicators? Nikon has been doing well it seems with its diffractive optics telephotos. Maybe Canon, the pioneer, is wanting to show folks just how to do it.

The length is in the patent. 296mm, subtract 20mm for the flange distance and it’s 276mm from front element to lens mount.

Why a 112mm front element? 300 / 2.8 = 107mm, but it’s really 300.6 / 2.91 = 103mm.

 

[DhlcadR6]

One up the Sony 300mm GM, gearholics are desperate for arms race

 

[juststeve]

112 mm was a number floating around in my brain after a long day. Something one might see mentioned in a 100-300/2.8 spec sheet. A filter diameter, alas. Took my caliper over to my 35 year old 300/2.8 L and saw its front diameter was 110 plus mm at the rubber lip. Likely about 104 mm at the glass. Whatever, the design presented in the patent appears to me to have the glass remarkably compressed to allow for the converter elements. And that GP notation might well mean something special. Diffractive optics, blue goo, I am only guessing. Something to do late after a long day.