EF 300mm f/4L IS USM
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Maybe they think it is 'good enough'. RF or not there are plenty of SLRs/DSLRs around ready to use a refreshed one with the latest IS. 
I would hate to buy one now and within a year a new one is released...
I would hate to buy one now and within a year a new one is released...
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I’ll predict they are refreshing for weight loss like the 400 IS III.
I’ll hope they present it as an RF with removable de-adapter for EF. Get it under 2000g even if it takes a fresnel. Or two versions with different rear mounts.
Release along with a mirrorless 1-series.
Oops, I just saw you were posting about f4. Never mind.
I’ll hope they present it as an RF with removable de-adapter for EF. Get it under 2000g even if it takes a fresnel. Or two versions with different rear mounts.
Release along with a mirrorless 1-series.
Oops, I just saw you were posting about f4. Never mind.
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A DO element you mean
I'm actually curious if they just abandoned that tech or if we'll see more of it once the big whites are moving to RF.
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A DO element you mean
I'm actually curious if they just abandoned that tech or if we'll see more of it once the big whites are moving to RF.
I was thinking the same thing, Canon newer actually released the updated 400mm and 600mm DO they were showing at the Canon Expo a few years back.
I hope that they show up as RF mount, but I fear they got scrapped because the new 400mm III and 600mm III were already light enough.
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Richard Shepherd, pro product marketing senior manager at Canon Europe, said about a week ago that Canon plans to focus on the RF mount, while still fully supporting the EF lens system, and will release new EF mount "should the market demand it". The EF 300mm f/4L IS USM is 23 years old. If there wasn't sufficient demand to upgrade it by now, I think it's a safe bet Canon wont ever upgrade it in EF mount.
An upgrade in the RF mount is a different question. Personally, I suggest not holding your breath. You seem like a nice person, I wouldn't like you to choke to death.
An upgrade in the RF mount is a different question. Personally, I suggest not holding your breath. You seem like a nice person, I wouldn't like you to choke to death.
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Seems that high ISOs, IS and a market demand for zooms make a 100-400 or ___-300 f5.6 more worthy of development investment than a 300 f4.
My research suggests that the Canon DO system is arguably a misnomer. They are what I would call encapsulated or immersion fresnel lens elements. They appear to rely on refraction by concentric lens elements that are orders of magnitude larger than the wavelength of light. They are for the purpose of reducing chromatic aberration in the manner of an achromatic lens with a second element of a different optical index. Except that element is formed using fresnel shapes molded on conventional lenses in thick coatings that are orders of magnitude greater that the wavelength of light. The rays are beneficially affected by the structure only by refraction, not diffraction.
That’s as best as I understand from the internet and Canon’s marketing. I should look for a patent and welcome any illumination. Also help understanding distinctions from Nikon’s system.
My research suggests that the Canon DO system is arguably a misnomer. They are what I would call encapsulated or immersion fresnel lens elements. They appear to rely on refraction by concentric lens elements that are orders of magnitude larger than the wavelength of light. They are for the purpose of reducing chromatic aberration in the manner of an achromatic lens with a second element of a different optical index. Except that element is formed using fresnel shapes molded on conventional lenses in thick coatings that are orders of magnitude greater that the wavelength of light. The rays are beneficially affected by the structure only by refraction, not diffraction.
That’s as best as I understand from the internet and Canon’s marketing. I should look for a patent and welcome any illumination. Also help understanding distinctions from Nikon’s system.
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The Nikon uses a classical Fresnel lens which uses refraction. Canon has its concentric rings of the separation of wavelength of light and is diffractive.
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The trouble with the Nikon lens, according to Optical Limits, is it's rendering of highlights (halos etc...).
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That’s what I expected but it seems inconsistent with Canon’s marketing images. My initial research found no use of diffractive optics for conventional imaging.
I’m very interested in learning more to fill the gap between marketing video simulations and technical applications unrelated to imaging.
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In practice there are very few, if any, reports of problems with highlights. The same is true with the 400mm DO II. These lenses are most frequently used by birders and nature photographers who are not photographing bright lights. Neither the Canon or Nikon offerings are at their best with backlit objects, however. I have never personally come across problems apart from loss of contrast with back lighting with the DO II.
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I'm researching, and this Canon patent publication is helpful. It has a grating pitch of 200 micrometers (about 400 wavelengths) It says diffraction, but I still don't understand how the majority of all rays could be "diffracted" to generate an image. If feels like a refractive system in which diffraction at the edges of the facets is an undesirable artifact to be minimized.
This Canon article has a lot of what might be described as "marketing hand-waving." it's entirely consistent with my initial take that the imaged rays are refracted, and the purpose of the advanced concept is to minimize undesirable diffracted rays. My sense is that marketing wanted to do everything they could to avoid the word "fresnel" as a poisonous (though technically accurate?) poison.
This image showing the fresnel rings makes my point. The imaging rays are passing through the facets, and diffraction at the transition lines is to be minimized.
This Canon article has a lot of what might be described as "marketing hand-waving." it's entirely consistent with my initial take that the imaged rays are refracted, and the purpose of the advanced concept is to minimize undesirable diffracted rays. My sense is that marketing wanted to do everything they could to avoid the word "fresnel" as a poisonous (though technically accurate?) poison.
This image showing the fresnel rings makes my point. The imaging rays are passing through the facets, and diffraction at the transition lines is to be minimized.
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200 µ is in the region of the grating pitch for a Fresnel diffraction lens. You can buy one cheaply from here https://www.aliexpress.com/item/1705307240.html to satisfy your curiosity. These are planar sheets of plastic without curvature for refraction.I'm researching, and this Canon patent publication is helpful. It has a grating pitch of 200 micrometers (about 400 wavelengths) It says diffraction, but I still don't understand how the majority of all rays could be "diffracted" to generate an image. If feels like a refractive system in which diffraction at the edges of the facets is an undesirable artifact to be minimized.
This Canon article has a lot of what might be described as "marketing hand-waving." it's entirely consistent with my initial take that the imaged rays are refracted, and the purpose of the advanced concept is to minimize undesirable diffracted rays. My sense is that marketing wanted to do everything they could to avoid the word "fresnel" as a poisonous (though technically accurate?) poison.
This image showing the fresnel rings makes my point. The imaging rays are passing through the facets, and diffraction at the transition lines is to be minimized.
The Fresnel refraction rings of the Nikon lens can be seen under a microscope, unlike those from Canon.
Nikon Nikkor AF-S 500 mm f/5.6E PF ED VR review - Introduction - LensTip.com
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"What is the main difference between Canon and Nikon technology? Canon never uses words ‘Fresnel element’ but they call their technology ‘Diffractive Optics’. It is in full accordance with the actual state of things. The height and pitch of concentric grating in the shape of optical elements showed in Canon diagrams have indeed the same size as the wavelength of falling light. As a result you deal not with refraction but diffraction. That’s why the official Canon materials never employ a term ‘Fresnel element’, only ‘Diffractive Optics’.
In the case of Nikon you deal with a classic Fresnel – its small concentric sections are visible under microscope and they cause refraction, not diffraction of light. Meanwhile in August 2018 we saw another PF lens, this time a 500 mm f/5.6 instrument."
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My current conclusion is that this report is simply not true, except that Canon avoided the "fresnel" term (presumably for marketing reasons).
The patent I cited and the photo show that the height and pitch are orders of magnitude greater than the wavelength of light.
There is no disclosed document anywhere that suggests that diffraction can be used to generate a sharp image. Diffraction optics are used to take a collimated beam and diverge it into a pattern that is desired. But never (that I have found) to focus from a point on an object to a point on an image sensor.
I'm open to being wrong, but it defies physics to create images by diffracting light.
What is shown is a fresnel with the head-slappingly brilliant feature of being immersed in a lens to address chromatic aberration, without all the issues with grooves in a lens to collect dust.
This is an internal fresnel element with macroscopically visible concentric segments that minimizes diffraction. Not a diffraction lens as used for other purposes.
Conclusion: Diffractive Optics is a misnomer contrary to reality. The Lenstip recviewier is revieing a Nikon lens, and makes a throwaway comment about a Canon lens that isn't in frint of him, and is simply wrong to the point of physical impossibility.
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