Patent: Is Canon planning to release catadioptric (mirror) super telephoto lenses?

AlanF

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Doesn't diffraction at f/15 spoil the resolution too much? Would it be any sharper than 800mm at f/11?
A 2000mm f/15 with a 133mm front element will greatly outresolve an 800mm f/11 which has a 73mm front element. For an extremely high resolution sensor, the resolution of the 2000/15 will be 133/73 times that of the 800/11, and this will tend to 2000/800 as the sensor resolution goes down. Briefly, the size of the diffraction disc from the f/15 will be 15/11 times that from the f/11 but the magnification is 2000/800 times that of the 800mm. The size of the diffraction disc becomes unimportant for low resolution sensors as the pixels become larger than the diffraction disc, and the resolution then depends on the focal length of the lens. For very high resolution sensors, the resolution of a lens depends on the diameter of its front element (entrance pupil).
 

SteveC

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Not possible on flat earth ,gravity pulls photons toward earth . You know you can see just things like 30km away becouse gravity unless big mountains.

OK, I was responding to a joke, but you just pushed my physics button, so here we go: It would ONLY be possible to see Australia from Europe on a flat earth. On the real, curved earth, of course Oz is well below the horizon in Europe, like thousands of miles below it. But even on a flat earth, as you mention there would be mountains, atmospheric haze, etc.

Photons won't drop much in 5-10 thousand kilometers when they travel 300,000km per second. They only have gravity acting on them for 1/30th of a second, and it responds just like a falling expensive lens; it will drop a grand total of 16 centimeters.
 

AlanF

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OK, I was responding to a joke, but you just pushed my physics button, so here we go: It would ONLY be possible to see Australia from Europe on a flat earth. On the real, curved earth, of course Oz is well below the horizon in Europe, like thousands of miles below it. But even on a flat earth, as you mention there would be mountains, atmospheric haze, etc.

Photons won't drop much in 5-10 thousand kilometers when they travel 300,000km per second. They only have gravity acting on them for 1/30th of a second, and it responds just like a falling expensive lens; it will drop a grand total of 16 centimeters.
Einstein said that in physics, imagination is more important than knowledge. So, let's use our imagination. " It would ONLY be possible to see Australia from Europe on a flat earth." It would be possible to see Australia even more easily if the world were concave and not flat! Anyway, it's all about spacetime curvature.
 

pape2

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Mar 19, 2021
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Photons won't drop much in 5-10 thousand kilometers when they travel 300,000km per second. They only have gravity acting on them for 1/30th of a second, and it responds just like a falling expensive lens; it will drop a grand total of 16 centimeters.
That measurement is made with assumption if world is sphere.
About mirror lenses , 400mm F3,5 could be nice BIF tele if these can focus as fast as L white lenses.
 
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SteveC

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Einstein said that in physics, imagination is more important than knowledge. So, let's use our imagination. " It would ONLY be possible to see Australia from Europe on a flat earth." It would be possible to see Australia even more easily if the world were concave and not flat! Anyway, it's all about spacetime curvature.

True that, good catch.

It's like the opening to Game of Thrones where the world seems to be on the inside of a spherical surface.
 

SteveC

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That measurement is made with assumption if world is sphere.
About mirror lenses , 400mm F3,5 could be nice BIF tele if these can focus as fast as L white lenses.

Which measurement? How much light would drop? For that, it doesn't matter what shape the world is, it does matter how much gravity there is, and we measure that directly any time we drop something.
 

RMac

5Diii 7D M5 C300
With stabilization and AF these could be immensely useable for long-lens type stuff (not all telephoto photography has specular out-of-focus highlights).

I wonder how these will work with the extenders. The FD 500mm f8 accepts the FD 1.4x.

Honestly for 500mm it's incredible how compact this setup can be...
IMG_9499.jpg
 

pape2

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Mar 19, 2021
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That's how we know the moon landings were faked. NASA messed up and showed supposed pictures of the earth that made it look spherical.
If you look disc from up its sphere ,no need magic for that :p .
Moonlanding faking is well known NASA plot. Truth is they figured moon is artificial object.
Untill they know is it mine or spaceship ,they dont want touch it even with long stick.
Thinking about human war history,,If peoples or aliens who made it are as warlike as we ,its bomb.
 

cayenne

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Cayenne, I have a pinhole, but have only used it once. I have never tried it on the R. Thanks for reminding me of it. Forgot all about it.
OH cool...glad I could help.

I think stuff like this is ALWAYS something to try to keep in mind, if for nothing else to get us out of our individual "ruts" so to speak...and help get your creativity thing going.

This weekend for me, I got out with some friends, loaded up come cameras...and at the end of it all, I discovered I'd shot only film?!?!

I had a new Russian HoritonT swing lens 35mm I wanted to try out, and I shot a lot on it (taking film in to be developed to negatives for me to scan later), and I set up my view camera that shoots 6x17 medium film for some very cool panoramic images.

I didn't do this on purpose, but I was just having so much fun trying new things, I ended up doing something different and boy, did it get my composition juices flowing.

Anyway, I plan a weekend day of trying to shoot mostly pinhole. Mine is a really cool looking one I got off Kickstarted by ONDU, I got the one that shoots 120 MF film, and can shoot 6x12 and smaller, depending on where you set the internal margin settings.

Here's a link to the pinhole I'm playing with : ONDU - Multi-Format Pinhole Camera

Sorry if I get so far off topic these days on threads...I'm just really branching out and trying all sorts of new things with photography, and well, I guess it has me very enthusiastic about it all.....and when I see a mention, I just jump in.

OH well, back to the actual topic at hand.
;)

cayenne
 
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CanonFanBoy

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OH cool...glad I could help.

I think stuff like this is ALWAYS something to try to keep in mind, if for nothing else to get us out of our individual "ruts" so to speak...and help get your creativity thing going.

This weekend for me, I got out with some friends, loaded up come cameras...and at the end of it all, I discovered I'd shot only film?!?!

I had a new Russian HoritonT swing lens 35mm I wanted to try out, and I shot a lot on it (taking film in to be developed to negatives for me to scan later), and I set up my view camera that shoots 6x17 medium film for some very cool panoramic images.

I didn't do this on purpose, but I was just having so much fun trying new things, I ended up doing something different and boy, did it get my composition juices flowing.

Anyway, I plan a weekend day of trying to shoot mostly pinhole. Mine is a really cool looking one I got off Kickstarted by ONDU, I got the one that shoots 120 MF film, and can shoot 6x12 and smaller, depending on where you set the internal margin settings.

Here's a link to the pinhole I'm playing with : ONDU - Multi-Format Pinhole Camera

Sorry if I get so far off topic these days on threads...I'm just really branching out and trying all sorts of new things with photography, and well, I guess it has me very enthusiastic about it all.....and when I see a mention, I just jump in.

OH well, back to the actual topic at hand.
;)

cayenne
Hmmmm.... maybe we should start a pinhole thread?
 
May 15, 2021
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With stabilization and AF these could be immensely useable for long-lens type stuff (not all telephoto photography has specular out-of-focus highlights).

I wonder how these will work with the extenders. The FD 500mm f8 accepts the FD 1.4x.

Honestly for 500mm it's incredible how compact this setup can be...
View attachment 197654
Indeed so - the FD 500mm f8 compared with the big white 100-400:
 

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usern4cr

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The surprising thing to me is that a pinhole can be bought for different angles of view. Never would have imagined that.
Well, I guess the distance from hole to film and film size is what will determine the angle of view.
Since both are probably fixed for the pinhole camera, that'd be the reason for different versions of them.
Which leads one to speculate that there might be a quality "zoom pinhole" out there with a mini-bellows (or simple helical thread mounted hole) tween the hole & film.
And I guess you could have a front rotating disc to select holes of various diameters to control speed.
 
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usern4cr

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Well, I guess the distance from hole to film and film size is what will determine the angle of view.
Since both are probably fixed for the pinhole camera, that'd be the reason for different versions of them.
Which leads one to speculate that there might be a quality "zoom pinhole" out there with a mini-bellows tween the hole & film.
And I guess you could have a front rotating disc to select holes of various diameters to control speed.
Didn't someone advertise "pinhole" lenses (or lens caps) for some mainstream cameras? I seem to remember that.
Of course, that obviates the joy of a simple child's box to make a magical photo. Well, that's how I felt (in a good way) when I got to use one.
 
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CanonFanBoy

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Well, I guess the distance from hole to film and film size is what will determine the angle of view.
Since both are probably fixed for the pinhole camera, that'd be the reason for different versions of them.
Which leads one to speculate that there might be a quality "zoom pinhole" out there with a mini-bellows (or simple helical thread mounted hole) tween the hole & film.
And I guess you could have a front rotating disc to select holes of various diameters to control speed.
You can find them at Adorama. I just have one, but distance from hole to sensor, don't think, has anything to do with the angle of view. I think it has more to do with the bevel around the hole, but I could be wrong. Exit: I think you are right. Distance from hole to sensor.
 
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