Patent: Canon is actively developing fast mirror lenses

photophil

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Jun 17, 2022
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This is not really an issue with distortion. Low contrast in the middle of the frame, which is a common shortcoming of mirror lenses, is easily corrected, but bokeh is something else entirely.

Here is that reference image from Optical Limits again — correcting bokeh in such an image sounds like a tall order even for sophisticated image editing software I think, let alone in-camera software.
 
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koenkooi

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Why not include bokeh correction in post? If they design lenses for people who don’t care about distortion correction this might be realistic.
Since DPAF basically gives you a depth map for free, this can even be done in-camera. Canon added 'clarity' and 'face relighting' for the current generation, so a faux bokeh mode wouldn't be that much of a technological leap.
 
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koenkooi

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This is not really an issue with distortion. Low contrast in the middle of the frame, which is a common shortcoming of mirror lenses, is easily corrected, but bokeh is something else entirely.

Here is that reference image from Optical Limits again — correcting bokeh in such an image sounds like a tall order even for sophisticated image editing software I think, let alone in-camera software.
If we define 'correcting' as 'blurring it further to make it less busy-looking', it might not be that hard. It's what phones do :)
 
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Does anyone tested or owned an EF 400 mm f/4 DO II ??
In 21 cm and weighting 2.1 Kg a fantastic 400 mm with absolutely nice bokeh
I tested several times, fantastic for hand shot.
And it was AF, worked pretty well with my 5D MkIV (in that times)
Problem was manufacturing time ... only a few ones available.
Probably some quality element was very hard to get it, the mirrors I guess.
But I would like to see a compact and lightweight RF 600 mm DO !!
 
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koenkooi

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Does anyone tested or owned an EF 400 mm f/4 DO II ??
In 21 cm and weighting 2.1 Kg a fantastic 400 mm with absolutely nice bokeh
I tested several times, fantastic for hand shot.
And it was AF, worked pretty well with my 5D MkIV (in that times)
Problem was manufacturing time ... only a few ones available.
Probably some quality element was very hard to get it, the mirrors I guess.
But I would like to see a compact and lightweight RF 600 mm DO !!
The RF600 f/11 is actually DO, but I bet you want a wider aperture :)
 
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20Dave

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Jan 19, 2013
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Question: Do mirror lenses stop down? I was under the impression that the aperture was fixed on a mirror lens and the only option was to use ND filters.
In amateur astronomy circles, some folks used to create off-centered masks, i.e. cover the aperture but with a hole that is away from the central obstruction. It is a jump in the focal ratio, not a gradual step up. The thought was that you would get a more "refractor-like" view, especially on brighter objects like planets. But I believe that practice has fallen by the wayside, as mirrors are better than they used to be and people don't want to give up the full resolution of the mirror.
 
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jam05

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Mar 12, 2019
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Interesting. Care to enlighten us as to who makes an f/1.2 or f/1.8 300mm lens?
Not specifically talking about the 300m. However Canon's EF 300mm F12.8 is $4000 while Sigma has one of those for about $2500. What prime L RF fast lenses has Canon released lately. You can literally count them on one hand. However it has been content to repeatedly push out F4 and F5 lenses as if the majority of photographers only shoot during daylight hours. Enough already with those and get on with the basic light gathering standard fast primes.
 
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neuroanatomist

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However Canon's EF 300mm F1.2 is $4000 while Sigma has one of those for about $2500.
What the heck are you talking about? You need to pick a different combination of focal length and aperture or a different price point, although if you prefer you can continue posting nonsense.
 
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entoman

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May 8, 2015
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Does anyone tested or owned an EF 400 mm f/4 DO II ??
In 21 cm and weighting 2.1 Kg a fantastic 400 mm with absolutely nice bokeh
I tested several times, fantastic for hand shot.
And it was AF, worked pretty well with my 5D MkIV (in that times)
Problem was manufacturing time ... only a few ones available.
Probably some quality element was very hard to get it, the mirrors I guess.
But I would like to see a compact and lightweight RF 600 mm DO !!
I may have misunderstood your post, but I get the impression that you think Canon's "DO" lenses include a mirror?

As you can see from the diagrams of the EF 400mm F4 DO and the RF 600mm F11, "DO" lenses do not have mirrors, only lenses :).

1674868210634.png

1674868265570.png
 
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neuroanatomist

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While Nikon releases high quality, lightweight, functional, super tele, Fresnel lenses, at relatively reasonable prices, all we see from Canon are patent filings. Sorry, I need product not promises.
Why not switch to Nikon, then? If they offer what you need and Canon does not, why just wait and complain. Of course, the latter option is free…
 
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AlanF

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While Nikon releases high quality, lightweight, functional, super tele, Fresnel lenses, at relatively reasonable prices, all we see from Canon are patent filings. Sorry, I need product not promises.
Nikon has only one Fresnel lens for mirrorless and it is a very pricey 800/6.3. Canon has two that are very cheap and light - the 600 and 800 f/11.
 
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