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



## Canon Rumors Guy (May 13, 2021)

> Keith over at Northlight uncovered a USPTO patent showing various optical designs for catadioptric lenses, better known as mirror lenses. The advantages to mirror lenses are reduced size, weight, and cost at long focal lengths.
> Some of the historical disadvantages to mirror lenses tend to be low contrast, fixed aperture, and doughnut bokeh. That’s not to say that Canon hasn’t improved or eliminated those issues in their designs.
> Optical designs that appear in this patent:
> 
> ...



Continue reading...


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## Del Paso (May 13, 2021)

With IS? Great !
If this lens is really super-compact, it could be a very interesting option "just in case".


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## hachu21 (May 13, 2021)

Agreed! I'm sure there is a market for compact and lightweight long télephoto lenses. Even at the cost of some image quality aspects. 
No matter what the photo snobs says, the donut bokeh do not kill an image. Especially if it's for a technical field or everything outside fine art.


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## jolyonralph (May 13, 2021)

Donut bokeh is inevitable with this kind of design - but as has been said that's not necessarily awful. If it means the difference between a $900 lens and a $9,000 lens with otherwise equal sharpness, I'll take those donuts!

It may be able to reduce donutting with lens corrections in software of course.


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## SnowMiku (May 13, 2021)

They seem like interesting consumer lenses, I wonder what the price of the Canon RF 800mm f/5 IS Mirror lens would be compared to the RF 800mm F/11 IS STM? Would it be cheeper because it's mirror lens or more expensive because of the wider aperture?

What would the Canon RF 2000mm f/15 IS be used for? I'm thinking it could be used for documenting distant birds in midday light on a tripod?


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## Josh Leavitt (May 13, 2021)

Hmm... Guess my R5 won't be a "mirrorless" camera for very long.


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## Fischer (May 13, 2021)

Warning: Mirror lenses and doughnuts made me a bokeh addict. And I'm still hooked! (You are warned)


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## miketcool (May 13, 2021)

If the lens is primarily used in astrophotography, bokeh is something you would never see.


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## mdcmdcmdc (May 13, 2021)

The reason “fast” and “mirror lens” generally don’t go together is because at ratios faster than f/8 or so, the central obstruction gets too big and you lose a lot of contrast. There have been mass-produced Schmidt cassegrain telescopes (SCTs) as fast as f/6.3, but generally they’re f/10. Maksutov cassegrains (MCTs) are typically slower still, f/12-15 or slower. 

That said, the f/5 and f/3.6 are definitely intriguing. I wonder what sort of magic Canon has up their sleeve for these!


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## usern4cr (May 13, 2021)

jolyonralph said:


> Donut bokeh is inevitable with this kind of design - but as has been said that's not necessarily awful. If it means the difference between a $900 lens and a $9,000 lens with otherwise equal sharpness, I'll take those donuts!
> 
> It may be able to reduce donutting with lens corrections in software of course.


If you could use software to properly "fill" the bokeh hole in post then this would be awesome. I don't know if that's possible with a single lens design which our cameras are.

This would make an ideal design for any pure-sky astronomy photos, since everything is focused at infinity and there should be no bokeh balls. In fact, some telescopes use this design but don't have the extra corrective lenses (shown in the patent) after the 2nd mirror, shortly before focusing on the sensor. So this would be even _*better*_ than some consumer telescopes optically. And that rumored future R body with active cooling (to keep the sensor heat & noise low) might be a nice partner for astro work with these lenses. I can see the rumors starting about a hopeful "astro" R... mount camera in the future.

You know, if Canon has gone this far, they could come out with a small RC (Ritchey-Chretien) lens design that would be amazing.

What a great option for Canon to bring to the R mount!


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## LensFungus (May 13, 2021)

I will buy the RF 2000mm to take portraits of my relatives in Australia... while being in Europe.


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## Mt Spokane Photography (May 13, 2021)

I have or had a old 600mm Sigma Mirror lens. When I got my EOS R, I put it on and tried it with focus peaking. I did not like the sharpness. I may try again with my R5, it has definitely better IQ. The problem is finding the time. I've owned 5 or 6 of the old mirror lenses, my 500mm Nikkor was fairly good. Most of the old ones were Sigmas.


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## Deleted member 381342 (May 13, 2021)

The interesting thing here is if they will have autofocus or will be manual focus only like the usual eBay special. A mirror lens with IS and AF would be quite interesting and you can always fill the donut holes yourself.


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## privatebydesign (May 13, 2021)

SnowMiku said:


> What would the Canon RF 2000mm f/15 IS be used for? I'm thinking it could be used for documenting distant birds in midday light on a tripod?


Not where I live, in general the atmospheric haze (heat haze) would reduce IQ to a milk bottle bottom most of the time.


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## privatebydesign (May 13, 2021)

Codebunny said:


> The interesting thing here is if they will have autofocus or will be manual focus only like the usual eBay special. A mirror lens with IS and AF would be quite interesting and you can always fill the donut holes yourself.


Zero chance it would be manual focus.

As for filling in the holes yourself, good luck with that!


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## Antono Refa (May 13, 2021)

miketcool said:


> If the lens is primarily used in astrophotography, bokeh is something you would never see.


Do astro photographers shoot with 400-800mm focal lengths? My impression is they either go wide to catch a big slice of the sky, or long to, say, have the moon fill the frame.

How much would IS help for astro, when the lens is mounted on a sturdy tripod anyway?


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## Dragon (May 13, 2021)

This is very cool and long overdue. Not likely that these are MF, so Cats that are a full stop faster than those of old with IS and AF would be very interesting. I have quite a collection of old mirror lenses and some are very sharp (e.g. 500 mm Minolta MD and 1000mm Nikon). The challenges are always accurate focus and adequate stability, although the R5 IBIS helps a lot with the latter. There is another angle to the timing of this. The Chinese telescope industry is currently in shambles. Between lawsuits, lack of production, and whatever, you simply cannot buy a Meade or Celestron telescope these days. That 2000 f/15 would be quite small and would be useful in telescope land. Note that the biggest of these (the 1200 f/8) is still only 6 inches in diameter and still tiny compared to a big white.


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## cayenne (May 13, 2021)

privatebydesign said:


> Zero chance it would be manual focus.
> 
> As for filling in the holes yourself, good luck with that!
> View attachment 197614


Hmm.

I actually think they look kinda cool!!

cayenne


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## AlanF (May 13, 2021)

Codebunny said:


> The interesting thing here is if they will have autofocus or will be manual focus only like the usual eBay special. A mirror lens with IS and AF would be quite interesting and you can always fill the donut holes yourself.


The patent does have IS. Minolta made a 500mm f/8 mirror reflex lens with AF that works on some Sony bodies. I prefer doughnuts,
​


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## neonlight (May 13, 2021)

Hmmm.. strange. First thought was a standard lens, but on seeing it was a mirror, disappointing. Useful for astro, focal lengths tend to be 1m or more. But IS? Long astro lenses will be mounted on heavy duty trackers which don't need it. And mmmm... donuts!
Not unless Topaz can come up with an AI donut filler?


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## neonlight (May 13, 2021)

...and another thing. Where's my 500 f/5.6 DO at £3-4k to compete with Nikon, Canon?


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## pape2 (May 13, 2021)

I wonder what wild life fears more ,harmless mirror shine 100meter away or big guy with big white 30meter away?
They could make also something to hide mirror shines when camera isnt taking pictures


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## AlanF (May 13, 2021)

neonlight said:


> Hmmm.. strange. First thought was a standard lens, but on seeing it was a mirror, disappointing. Useful for astro, focal lengths tend to be 1m or more. But IS? Long astro lenses will be mounted on heavy duty trackers which don't need it. And mmmm... donuts!
> Not unless Topaz can come up with an AI donut filler?


We fill doughnuts with jam.


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## emag (May 13, 2021)

While most of my experience with catadioptric lenses comes from astrophotography with Schmidt Cassegrain telescopes, I have over the years had a couple of these lenses to play with for conventional photography. They ranged from a cheap 500mm POS to the very nice Questar 700, which did well after disassembly and cleaning. Here are some comparison shots with the Q700 and a Tamron 150-600. These lenses have their uses and I would welcome the addition of IS and AF. They'll never satisfy perfectionists and are horrible with specular highlights, but are an economical way to achieve long reach.


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## miketcool (May 13, 2021)

Antono Refa said:


> Do astro photographers shoot with 400-800mm focal lengths? My impression is they either go wide to catch a big slice of the sky, or long to, say, have the moon fill the frame.
> 
> How much would IS help for astro, when the lens is mounted on a sturdy tripod anyway?


1200mm and up puts you in amateur telescope ranges that are useful. Lens IS coupled with sensor IBIS allows in camera/lens tracking due to earth rotation. The stabilizing would allow for longer exposures where you could track and stack images to get higher resolution shots of stars and objects.


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## RedPixels (May 13, 2021)

Antono Refa said:


> Do astro photographers shoot with 400-800mm focal lengths? My impression is they either go wide to catch a big slice of the sky, or long to, say, have the moon fill the frame.
> 
> How much would IS help for astro, when the lens is mounted on a sturdy tripod anyway?



Ultra Wide field which is done for landscapes to catch the Milky Way is usually less than 50mm. Specific sky targets such as galaxies and nebulae sit around 200-450mm. There are some deep space targets and close up lunar photos that do benefit from longer focal lengths, but for general purposes 200-450mm is the sweet spot depending on the camera and chip size. For the moon, I have an 8" f/10 SCT that I have to reduce down to f/6.3 to fit it into the frame which brings the focal length down to about 1280mm, so this would be comparable to the 1200mm lens. Also, IS doesn't really help when doing astrophotography because you are usually imaging on a guided mount or stacking widefield exposures from a tripod.


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## Mugglemind (May 13, 2021)

Antono Refa said:


> Do astro photographers shoot with 400-800mm focal lengths? My impression is they either go wide to catch a big slice of the sky, or long to, say, have the moon fill the frame.
> 
> How much would IS help for astro, when the lens is mounted on a sturdy tripod anyway?


I remember watching a youtube video with Jared Polin, where he took video of Saturn using the R5, 800mm f/11 and 2x converter. Was very shaky, because he had the wrong head on his tripod. But seeing the rings of Saturn in a video was amazing.


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## AccipiterQ (May 13, 2021)

ME: I'm so glad I have my EF 600iii, I'll never need a longer lens, my big lens purchase days are over!
Canon: Bad news from the future


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## bergstrom (May 13, 2021)

make a 1200mm 2.8


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## Alam (May 13, 2021)

The only thing that stopping me from buying mirror lens is absence of IS

Thank god i haven't pulled the trigger on rf 800 f11 yet


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## LDS (May 13, 2021)

mdcmdcmdc said:


> there have been mass-produced Schmidt cassegrain telescopes (SCTs) as fast as f/6.3, but generally they’re f/10


Because they are usually a good compromise for focal length (and thereby magnification), size/weigth and costs. There are several astrographs that are faster. For example Officina Stellare makes a 980/2.8 and a 720/2.2 - although they don't use a pure Schmidt-Cassegrain schema but a Riccardi-Honders one - it's a modification with added lenses just like the Canon design to obtain a larger corrected field.

Not something you wish to use handheld, anyway, since the 980mm weights 35kg.



usern4cr said:


> but don't have the extra corrective lenses (shown in the patent) after the 2nd mirror, shortly before focusing on the sensor


They have - it's were you attach different types of eyepieces to select the magnification. Although you can also attach a camera directly without any other optics.


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## calfoto (May 13, 2021)

With a Nikon F to Canon R mount adapter I've been able to turn my R5 into a 500mm catadioptric "CanNikon"

I have another adapter that allows me to morph the R5 into a LeiCanon
​


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## AlanF (May 13, 2021)

Alam said:


> The only thing that stopping me from buying mirror lens is absence of IS
> 
> Thank god i haven't pulled the trigger on rf 800 f11 yet


The patent has IS on the lenses


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## Ozarker (May 13, 2021)

privatebydesign said:


> Zero chance it would be manual focus.
> 
> As for filling in the holes yourself, good luck with that!
> View attachment 197614


Yeah, but I think that's really cool just like it is.


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## Ozarker (May 13, 2021)

cayenne said:


> Hmm.
> 
> I actually think they look kinda cool!!
> 
> cayenne


I agree very much. It's a cool shot.


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## Ozarker (May 13, 2021)

Dragon said:


> This is very cool and long overdue. Not likely that these are MF, so Cats that are a full stop faster than those of old with IS and AF would be very interesting. I have quite a collection of old mirror lenses and some are very sharp (e.g. 500 mm Minolta MD and 1000mm Nikon). The challenges are always accurate focus and adequate stability, although the R5 IBIS helps a lot with the latter. There is another angle to the timing of this. The Chinese telescope industry is currently in shambles. Between lawsuits, lack of production, and whatever, you simply cannot buy a Meade or Celestron telescope these days. That 2000 f/15 would be quite small and would be useful in telescope land. Note that the biggest of these (the 1200 f/8) is still only 6 inches in diameter and still tiny compared to a big white.


I know nothing about astro. Most of the posts I see here about astro want fast lenses. Am I correct to assume that these mirror lenses need to have a tracker for astro? I'm guessing the guys real serious about astro already have one?


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## Ozarker (May 13, 2021)

pape2 said:


> I wonder what wild life fears more ,harmless mirror shine 100meter away or big guy with big white 30meter away?
> They could make also something to hide mirror shines when camera isnt taking pictures


I invented the dish rag for exactly that purpose


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## Ozarker (May 13, 2021)

neonlight said:


> ...and another thing. Where's my 500 f/5.6 DO at £3-4k to compete with Nikon, Canon?


Unless you're ready to switch to Nikon, the Nikon is no competition. Otherwise, I predict 2027.


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## padam (May 13, 2021)

CanonFanBoy said:


> Unless you're ready to switch to Nikon, the Nikon is no competition. Otherwise, I predict 2027.


I predict never. They are simply looking at offering different things and not going directly head-to-head against each other with every lens.
Canon is going 400/4 versus 500/5.6, 100-400/5.6-7.1 and 100-500/4.5-7.1L versus a 100-400/4.5-5.6 and 200-600/5.6-6.3 (I guess the Nikon 200-600 will be close to Sony in this case) etc. etc.


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## AlanF (May 13, 2021)

padam said:


> I predict never. They are simply looking at offering different things and not going directly head-to-head against each other with every lens.
> Canon is going 400/4 versus 500/5.6, 100-400/5.6-7.1 and 100-500/4.5-7.1L versus a 100-400/4.5-5.6 and 200-600/5.6-6.3 (I guess the Nikon 200-600 will be close to Sony in this case) etc. etc.


I am a very happy RF 100-500mm user, as evidenced by the number of shots with it and the RF 1.4x and 2x I’ve posted. But that Nikon 500mm f/5.6 PF is the best lightweight lens I‘ve owned and I’d rather buy the Canon equivalent of it than a 400/4 even if they could reduce the weight right down. The range with TCs of 500-700-1000mm (like on the 100-500mm too) is more useful to me than 400-560-800mm. My 400mm DO II spent most of its time with a 1.4 or 2xTC on it.


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## DBounce (May 13, 2021)

I really like the idea of this lens for moon photography.


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## blackcoffee17 (May 14, 2021)

LensFungus said:


> I will buy the RF 2000mm to take portraits of my relatives in Australia... while being in Europe.



You would be surprised how short 2000mm can be on a full frame camera when shooting birds in nature for example.


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## dolina (May 14, 2021)

If the lens is that cheap then dont complain about donuts or speed.

Pay more for no donuts and more speed.


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## efmshark (May 14, 2021)

Canon Rumors Guy said:


> Continue reading...


Deficiencies and distortion characteristics of catadioptric lenses can be pretty well modeled. Maybe Canon found a way to definitively fix these issues with post-processing.


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## Nelu (May 14, 2021)

LensFungus said:


> I will buy the RF 2000mm to take portraits of my relatives in Australia... while being in Europe.


Yeah, it works pretty well for this social distancing thing...


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## nemophoto (May 14, 2021)

I love mirror lenses! I still own a 35-year old Canon FD 500/8 lens. I am most excited by the adapter I now have -- an FD to RF. After some test frames with my R5, great lens, very good sharpness and easy to use now that there is focus peaking. So, an RF with IS and even autofocus? Bring it on. As for the doughnuts? Love them too. Something different. People obsess too much about bokeh and not enough about what they are shooting.


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## Mr Majestyk (May 14, 2021)

Oh no the world's first $10K mirror lens incoming. Maybe they can surpise us and it has excellent IQ, and is under $5K.

Please just release a 1000 f/8 DO IS coming in at no more than 2.4kg and we are good to go. Yes I do realise that won't be cheap, but neither is a 500/600 f/4 and and this would be very nice for birding.


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## Dragon (May 14, 2021)

CanonFanBoy said:


> I know nothing about astro. Most of the posts I see here about astro want fast lenses. Am I correct to assume that these mirror lenses need to have a tracker for astro? I'm guessing the guys real serious about astro already have one?


Most catadioptric telescopes are between f/10 and f/15, so these lenses are average to fast for that application, and yes a tracker is a typical requirement. As to everybody already having one, Covid has inspired a large number of folks to take up back yard astro observation and photography, and that has contributed to the shortage of telescopes, so no, not everyone has one. Fast lenses are desirable for short exposure wide angle shots, but very few longer telescopes are fast.


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## pape2 (May 14, 2021)

CanonFanBoy said:


> I invented the dish rag for exactly that purpose


i was thinking something automatic ,like rotating polaroid filter but maybe better


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## Pixel (May 14, 2021)

What else ya got, Canon?


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## Mugglemind (May 14, 2021)

LensFungus said:


> I will buy the RF 2000mm to take portraits of my relatives in Australia... while being in Europe.


Sadly, don't quite think it will get _that_ far!

This is Elizabeth Tower (and you can see the Big Ben bell inside) from 4 miles away. Used the R5, 800mm f/11, 2x converter, and the built in 1.6x crop to get it. Can vaguely make out a few of the workers on the scaffolding at that distance too.


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## Alam (May 14, 2021)

AlanF said:


> The patent has IS on the lenses


Yeah, I'm so excited, i hope it's also autofocus lens, I don't care about donut bokeh as long s it got autofocus
If manual then, well, I'll get 800 f11


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## padam (May 14, 2021)

AlanF said:


> I am a very happy RF 100-500mm user, as evidenced by the number of shots with it and the RF 1.4x and 2x I’ve posted. But that Nikon 500mm f/5.6 PF is the best lightweight lens I‘ve owned and I’d rather buy the Canon equivalent of it than a 400/4 even if they could reduce the weight right down. The range with TCs of 500-700-1000mm (like on the 100-500mm too) is more useful to me than 400-560-800mm. My 400mm DO II spent most of its time with a 1.4 or 2xTC on it.


I reckon the new 400/4 will be popular if they can make it even more compact, and no doubt performance is going to improve significantly with the RF converters as well, so it may work with a higher pixel density APS-C body as well.
It could be a more serious alternative to the 400/2.8 with the upcoming mirrorless cameras with more advanced AF systems.
There is also the rumoured 200-500/4 to replace the 200-400/4 + 1.4x, looks like a pretty significant upgrade if they make it.

Strangely, Nikon doesn't seem to at least refresh the 500/5.6 for the Z-mount. There was also a patent for a 600/5.6, I hope their 200-600/5.6-6.3 will be excellent, but it's not nearly the same thing and they have quite a way to go just to release all that's still blacked out on their roadmap.

I kind of like the 800/11 for what it is (great to start with and it can't be any smaller and lighter than it is), but it needs a second body to work because of the MFD and fixed aperture (and the great 100-500/4.5-7.1 + 1.4x may be a straight up replacement, but the zoom limitation with the teleconverters is annoying, especially for the money), and they said they are considering more lenses like this, so I wouldn't mind if they could expand the range and do a 1000/11 as well, although it looks like that 1200/8 is what they are going for instead if that's what they've meant by that statement.
If it minimises the shortcomings with mirror lenses, it could be really good., but it won't be that cheap. and again with a fixed aperture, so I wonder how is the DOF, it is already marginal with the 800/11 at its ideal range of 6-12 meters for birds.


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## pzyber (May 14, 2021)

Could be nice astrophoto lenses. The Canon RF 2000mm f/15 IS with 2x extender could even be great for planetary photography. Filming 8k RAW with the R5 then stacking the best of the frames.


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## justaCanonuser (May 14, 2021)

Very interesting what Canon would make out of this old lens design. As others have stated here, the classic mirror lenses have very special characteristics, in fact you could use them for arts photography, like some people use pinhole or cheap Lomo cameras for their arts prints. Here is a good article, based on those classic mirror design lenses - btw astronomical optical telescops basically use the same principle:









Mirror Lenses: Lightweight Super-Telephotos that Are Affordable


This is a short primer on mirror, or as they are also known - catadioptric lenses, which are long telephoto lenses that are light, small, and do not cost a fortune.




www.bhphotovideo.com


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## cayenne (May 14, 2021)

justaCanonuser said:


> Very interesting what Canon would make out of this old lens design. As others have stated here, the classic mirror lenses have very special characteristics, in fact you could use them for arts photography, like some people use pinhole or cheap Lomo cameras for their arts prints. Here is a good article, based on those classic mirror design lenses - btw astronomical optical telescops basically use the same principle:
> 
> 
> 
> ...


Actually, you get get some surprisingly GOOD images out of a well made pinhole camera.
Surprisingly good.


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## Alam (May 14, 2021)

Sony : let's make as wide lens as possible, let's see the bigger picture
Nikon: let's make exact copy of our dslr lens, easiest way to success is imitating past experience.
Canon : lol, as far as possible, social distancing madafaka


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## Ozarker (May 14, 2021)

cayenne said:


> Actually, you get get some surprisingly GOOD images out of a well made pinhole camera.
> Surprisingly good.


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.


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## Skyscraperfan (May 14, 2021)

Doesn't diffraction at f/15 spoil the resolution too much? Would it be any sharper than 800mm at f/11?


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## SteveC (May 14, 2021)

LensFungus said:


> I will buy the RF 2000mm to take portraits of my relatives in Australia... while being in Europe.


Flat earther?


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## AlanF (May 14, 2021)

Skyscraperfan said:


> 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).


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## pape2 (May 15, 2021)

SteveC said:


> Flat earther?


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.


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## SteveC (May 15, 2021)

pape2 said:


> 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.


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## AlanF (May 15, 2021)

SteveC said:


> 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.


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## pape2 (May 15, 2021)

SteveC said:


> 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 (May 15, 2021)

AlanF said:


> 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.


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## SteveC (May 15, 2021)

pape2 said:


> 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.


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## RMac (May 17, 2021)

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...


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## stevelee (May 17, 2021)

pape2 said:


> That measurement is made with assumption if world is sphere.


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.


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## pape2 (May 17, 2021)

stevelee said:


> 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  .
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.


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## cayenne (May 17, 2021)

CanonFanBoy said:


> 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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## Ozarker (May 17, 2021)

cayenne said:


> 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.
> 
> ...


Hmmmm.... maybe we should start a pinhole thread?


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## cayenne (May 17, 2021)

CanonFanBoy said:


> Hmmmm.... maybe we should start a pinhole thread?


That wouldn't suck.


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## rtweed (May 18, 2021)

RMac said:


> 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.
> 
> ...


Indeed so - the FD 500mm f8 compared with the big white 100-400:


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## justaCanonuser (May 20, 2021)

cayenne said:


> Actually, you get get some surprisingly GOOD images out of a well made pinhole camera.
> Surprisingly good.


Yes, I know, in fact I currently make my mind up if I should get or make one again. Had one when I was young.


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## Ozarker (May 20, 2021)

justaCanonuser said:


> Yes, I know, in fact I currently make my mind up if I should get or make one again. Had one when I was young.


The surprising thing to me is that a pinhole can be bought for different angles of view. Never would have imagined that.


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## usern4cr (May 20, 2021)

CanonFanBoy said:


> 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 (May 20, 2021)

usern4cr said:


> 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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## jolyonralph (May 27, 2021)

privatebydesign said:


> Zero chance it would be manual focus.
> 
> As for filling in the holes yourself, good luck with that!
> View attachment 197614


Ooooooooooo!


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## Ozarker (May 27, 2021)

usern4cr said:


> 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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## Dragon (Mar 24, 2022)

Alam said:


> fa





RMac said:


> 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.
> 
> ...


That fd 500 works well with the fd 2x B TC as well. Here is a 100% crop of a shot with the fd 500 and 2x B attached to an M6 II (that's 1000 mm with a pixel density equivalent to an 82 MP FF sensor). I have two copies of the lens and this is the best one. Note the fine lettering in the bottom right corner of the label. The 1000mm F/11 Nikon and the 500mm Minolta MD are also quite good and the Tamron 500 is the best at close focus distances. The 500mm Nikon is also good, but heavier than the other 500s and it has a very long minimum focus distance. I have a couple of the Sigma 600s and they are quite soft, particularly in comparison to the others mentioned. I do think cats with IS and AF would be truly useful as the primary dings on all the older lenses are difficulty of focus and stability. For situations where you can overcome those two problems, all but the Sigmas make quite decent images.


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## Johnw (Apr 14, 2022)

RedPixels said:


> Specific sky targets such as galaxies and nebulae sit around 200-450mm.


Well it actually depends entirely on which target. Some close by galaxies like Andromeda will fill the frame at those lengths. Others would be better at 1500, others would be better at 3000, etc.


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