# A bit of history about Canon and catadioptric (mirror) lenses



## Canon Rumors Guy (May 14, 2021)

> There has been a lot of talk about Canon and catadioptric lenses (mirror) since a patent surfaced with new lens designs likely for the RF mount. It has been rumored for quite some time that Canon would be bringing an RF 1200mm f/8 lens for the EOS R system, which could actually be a mirror lens.
> Canon does have a history with mirror lenses, including the behemoth Canon 5200mm f/14 along with an 800mm f/3.8 and a 2000mm f/11. A Canon Rumors reader sent me a brochure for these three lenses and I found it to be a fun read.
> These lenses were developed in the mid-1960s and can still fetch a king’s ransom on the used market. The 5200mm f/14 sold for about $50,000 a few years ago on ebay.
> Check out the official Canon brochure...



Continue reading...


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## TAF (May 14, 2021)

And if you adapt your 5200mm to an APS-C camera...


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## HenWin (May 14, 2021)

If Canon brings out some cat lenses, I hope they're a bit lighter than these puppies!




I kinda remember the Nikon cat lens (for F models), and it was comfortably light (hand-holdable) at 500mm.


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## neuroanatomist (May 14, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...


...it's still a 5200mm lens.


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## mdcmdcmdc (May 14, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...


Ooh you said a bad word: APS-C.
Bring on the h8ers...


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## EOS 4 Life (May 14, 2021)

I am not sure that I would trust selling something worth $50K on eBay.


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## Ozarker (May 14, 2021)

I don't appreciate Canonrumors publishing what I paid on ebay for the 5,200mm.


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## Jsjamesok (May 14, 2021)

100 kgs for the 5200! That would be interesting to handle. I would like to touch it.


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## Del Paso (May 14, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...


Are you kidding?
I suggest Micro four thirds.
PS: where are thou, sony ?


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## SteveC (May 14, 2021)

I've been contemplating a new telescope. With the right adapter it would essentially become something like this, just not Canon brand.


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## AlanF (May 14, 2021)

EOS 4 Life said:


> I am not sure that I would trust selling something worth $50K on eBay.


I am even less sure I would trust buying something costing $50K on eBay.


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## JPAZ (May 14, 2021)

But no IS? Forget it


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## Chig (May 14, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...


Micro 4/3rds maybe ?


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## Chig (May 14, 2021)

The 800mm f/3.8 looks interesting with such a bright aperture ,but a bit heavy at 15kg


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## AJ (May 14, 2021)

JPAZ said:


> But no IS? Forget it


No kidding. How on Earth would you keep a 5200 mm lens steady. That and atmospheric turbulence would be big challenges.


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## neuroanatomist (May 15, 2021)

JPAZ said:


> But no IS? Forget it


It comes with IS – a large block of granite.


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## EOS 4 Life (May 15, 2021)

JPAZ said:


> But no IS? Forget it


Just use a gimbal and it is the perfect vlogging lens


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## RGF (May 15, 2021)

I want all 3


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## DBounce (May 15, 2021)

I wonder how much the new canon lenses will cost?


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## Stig Nygaard (May 15, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...


Scary


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## pape2 (May 15, 2021)

Needing teleconverter if shooting big butterflyes with 5200mm .
and something like this to push it around.





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The Veloped Jakt rollator will be your trustworthy rollator on your hunting trip. With its off-road capacity and climbing wheel, you can easily overcome roots, gravel, rock and dirt on your way to the hunting ground. The rifle bag attaches to the rollator




www.trionic.ca


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## rrdoh (May 15, 2021)

I still have my FD500 f8 reflex lens, works well with a cheap FD to EF adapter: sadly no AF or IS in 1985. Doesn't get a lot of use but am happy to see the possibility of new reflex/cat lenses coming.


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## AlanF (May 15, 2021)

pape2 said:


> Needing teleconverter if shooting big butterflyes with 5200mm .
> and something like this to push it around.
> 
> 
> ...


Its minimus focal distance is 120m. So, it will give you the equivalent of the magnification of a 520mm lens at 12m. So, a 2x TC will be needed, or better still a 4x.


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## pape2 (May 15, 2021)

AlanF said:


> Its minimus focal distance is 120m. So, it will give you the equivalent of the magnification of a 520mm lens at 12m. So, a 2x TC will be needed, or better still a 4x.


I got bad hay allergy ,would love shoot flower field butterflys without actually going close to hays


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## Cochese (May 15, 2021)

TAF said:


> And if you adapt your 5200mm to an APS-C camera...



Or, and here me out, attach it to a high megapixel full frame. And then crop. Same effect, more raw image to work with. 

You're not adding reach to your images, only cropping the full frame. 

Unless both your full frame and crop sensor are the same resolution, anyway.


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## masterpix (May 15, 2021)

Canon Rumors Guy said:


> Continue reading...


There was (still use it) the FD 500mm F8 CAT lens.


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## RunAndGun (May 15, 2021)

EOS 4 Life said:


> I am not sure that I would trust selling something worth $50K on eBay.



I’ve actually seen way more expensive things on eBay. YEARS ago, in the live(TV) sports world, there were two main companies that provided the wireless transmission services for the handheld cameras and other remote/robotic cameras. At one point, the smaller company failed and was put up for sale. I about fell out of my chair one day when I was looking around on eBay and the company was listed for sale on an eBay auction.


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## jvillain (May 15, 2021)

I wonder how 2000mm f/11 would work for shooting action sequences on bright days with modern low noise cameras. Got to think you would get all the lens compression you will ever need with out the need for a ton of ND.


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## LDS (May 15, 2021)

What it interesting is Canon is no longer using the old Maksutov-Cassegrain design of those lenses, which was cheaper than the Schimdt-Cassegrain one, not using the aspherical front element. It looks inspired by recent Busack-Honders-Riccardi designs, with the reflective coating on the mirror back instead its front surface, and the positive front lens.

So it looks Canon did some real new researches and designs for these lenses.


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## Dragon (May 15, 2021)

HenWin said:


> If Canon brings out some cat lenses, I hope they're a bit lighter than these puppies!
> 
> 
> 
> ...


The Canon FD 500mm Cat is lighter than the Nikon and quite usable on an R5 with IBIS on. It is also pretty reasonable on fleabay.


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## EOS 4 Life (May 15, 2021)

jvillain said:


> I wonder how 2000mm f/11 would work for shooting action sequences on bright days with modern low noise cameras. Got to think you would get all the lens compression you will ever need with out the need for a ton of ND.


I am obviously a Canonite but I also use micro four-thirds because I swore off heavy telephoto lenses.
However, I have not seen micro four-thirds lenses longer than 800 mm.
2000 mm with APS-C would blow micro four-thirds out of the water.
There is still a sweet spot for micro four-thirds with telephoto zooms since the extra crop increases the zoom range.
After that, the main advantage is IS.
Only the R5 and R6 rival my G9 in image stabilization at twice or three times the price.


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## JoeDavid (May 15, 2021)

rrdoh said:


> I still have my FD500 f8 reflex lens, works well with a cheap FD to EF adapter: sadly no AF or IS in 1985. Doesn't get a lot of use but am happy to see the possibility of new reflex/cat lenses coming.
> View attachment 197632


Yea, back in film days I had a 500mm f8 Tokina lens that was quite sharp. It was compact enough that no one thought it was a 500mm lens. Once you get over the donut bokeh, one with autofocus would be welcome in my kit. I wish Canon had used a reflex/cat design with the 600 and 800 lenses. They could have been smaller and faster. Those are stuck at f11. I’d rather be stuck at f8.


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## AlanF (May 15, 2021)

EOS 4 Life said:


> I am obviously a Canonite but I also use micro four-thirds because I swore off heavy telephoto lenses.
> However, I have not seen micro four-thirds lenses longer than 800 mm.
> 2000 mm with APS-C would blow micro four-thirds out of the water.
> There is still a sweet spot for micro four-thirds with telephoto zooms since the extra crop increases the zoom range.
> ...


Micro 4/3 may have a crop factor of 2 over FF but the resolution of the G9 sensor isn't two times higher than that of the R5 because of the much higher pixel density of the FF. The pixel pitch of the G9 is 3.32 µ compared with 4.38 µ for the R5, which means the G9 has only 32% more "reach". The 90D and M6II both outresolve the G9 or Olympus equivalents.


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## SteveC (May 15, 2021)

Cochese said:


> Or, and here me out, attach it to a high megapixel full frame. And then crop. Same effect, more raw image to work with.
> 
> You're not adding reach to your images, only cropping the full frame.
> 
> Unless both your full frame and crop sensor are the same resolution, anyway.



Yes. "Reach" depends on pixel density and focal length, not the size of the sensor. Of course if it's a big sensor you end up having to crop in post (or use the crop mode if the camera has one) but you still get the same results as you would with a smaller sensor of the same density.

That being said, crop sensors tend to have a higher pixel density, so it's easy enough to get a little lazy just equate them with better reach _because_ of the APS-C sensor. And as far as I know the best pixel density Canon has to offer is on the M6-II and the 90D. The R5 has the same density as a (hypothetical) 17MP APS-C camera. Not so long ago that would have been killer megapixels, today the APS-C birders and the like find it a step down, and it actually is, from their 7Ds.


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## EOS 4 Life (May 16, 2021)

AlanF said:


> Micro 4/3 may have a crop factor of 2 over FF but the resolution of the G9 sensor isn't two times higher than that of the R5 because of the much higher pixel density of the FF. The pixel pitch of the G9 is 3.32 µ compared with 4.38 µ for the R5, which means the G9 has only 32% more "reach". The 90D and M6II both outresolve the G9 or Olympus equivalents.


While you are correct, I do also have an R5 which makes me use the G9 less but Panasonic MFT lenses are much smaller for the same reach.
The main point of my comment was that advantage is getting less and less but it does still exist.
MFT and RF have the exact same flange distance and MFT is smaller so I am not sure why there is no MFT to EOS R adapter.
I guess maybe the size difference is not enough to fit an MFT adapter into an RF mount.


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## Ozarker (May 16, 2021)

EOS 4 Life said:


> While you are correct, I do also have an R5 which makes me use the G9 less but Panasonic MFT lenses are much smaller for the same reach.
> The main point of my comment was that advantage is getting less and less but it does still exist.
> MFT and RF have the exact same flange distance and MFT is smaller so I am not sure why there is no MFT to EOS R adapter.
> I guess maybe the size difference is not enough to fit an MFT adapter into an RF mount.


If they have the same exact native flange distance, doesn't adding the adapter change the flange distance from lens to sensor? Absolutely. That is probably why there is no adapter. The reason EF to RF works is because EF lenses have a naturally greater flange distance than RF. So adding the adapter makes up for that. So, to me, this is the same reason RF isn't adapted to EF. You increase the flange distance with an adapter.

*I have no idea what the flange distance measurement is for MFT vs RF.* Just assuming @EOS 4 Life is correct.


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## Del Paso (May 16, 2021)

CanonFanBoy said:


> If they have the same exact native flange distance, doesn't adding the adapter change the flange distance from lens to sensor? Absolutely. That is probably why there is no adapter. The reason EF to RF works is because EF lenses have a naturally greater flange distance than RF. So adding the adapter makes up for that. So, to me, this is the same reason RF isn't adapted to EF. You increase the flange distance with an adapter.
> 
> *I have no idea what the flange distance measurement is for MFT vs RF.* Just assuming @EOS 4 Life is correct.


Sometimes it works!
A Spanish company (Leitax) replaces Nikon F bayonets with EOS EF ones, or Leica R's with EF bayonets, so there's no need for an adapter which, as you mentioned, adds flange distance. Due to the high precision manufactoring of these bayonets, F Nikons or R Leicas work perfectly well on EOS DSLRs (with RF-EF adapter also on EOS R).
Of course, would adapting MFT to RF make sense??? That is the question...


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## EOS 4 Life (May 16, 2021)

CanonFanBoy said:


> If they have the same exact native flange distance, doesn't adding the adapter change the flange distance from lens to sensor? Absolutely. That is probably why there is no adapter. The reason EF to RF works is because EF lenses have a naturally greater flange distance than RF. So adding the adapter makes up for that. So, to me, this is the same reason RF isn't adapted to EF. You increase the flange distance with an adapter.
> 
> *I have no idea what the flange distance measurement is for MFT vs RF.* Just assuming @EOS 4 Life is correct.


There is no glass in the adapter so it would not necessarily increase the flange distance.
It would just be one mount inside of another.
The diameter seems like a bigger challenge because the adapter would need to connect to the RF pins while at the same time having the MFT pins for lenses to connect to.


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## 20Dave (May 16, 2021)

I wonder how these Canon lenses would compare with the equivalent telescopes. The Celestron Edge line of scopes (see here) would be one of the competitors. One big difference would be the mounting assembly. Telescopes typically come with dovetail bars to attach to astro mounts rather than tripods.


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## blackcoffee17 (May 16, 2021)

JoeDavid said:


> Yea, back in film days I had a 500mm f8 Tokina lens that was quite sharp. It was compact enough that no one thought it was a 500mm lens. Once you get over the donut bokeh, one with autofocus would be welcome in my kit. I wish Canon had used a reflex/cat design with the 600 and 800 lenses. They could have been smaller and faster. Those are stuck at f11. I’d rather be stuck at f8.



Oh, please no! At least those 600mm and 800mm lenses have pretty good image quality with nice bokeh. If they were mirror lenses I would just ignore them as the usage is very limited. I don't mind Canon making few mirror lenses but we need affordable high quality telephotos also.


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## Dragon (May 16, 2021)

20Dave said:


> I wonder how these Canon lenses would compare with the equivalent telescopes. The Celestron Edge line of scopes (see here) would be one of the competitors. One big difference would be the mounting assembly. Telescopes typically come with dovetail bars to attach to astro mounts rather than tripods.


I suspect they will be optically superior if they come to pass. AFAIK the Celestron Edge uses a spherical mirror with with a correction lens. The Canon patent distinctly shows and aspheric mirror design which should be inherently superior. In the end, it is all in the implementation, but the odds are very high that Canon will do a better job. The patent also shows a considerably more complex lens grouping than any of the conventional telescopes. Some of that will no doubt be due to the IS, but I suspect more care in correction as well.


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## Dragon (May 17, 2021)

rrdoh said:


> I still have my FD500 f8 reflex lens, works well with a cheap FD to EF adapter: sadly no AF or IS in 1985. Doesn't get a lot of use but am happy to see the possibility of new reflex/cat lenses coming.
> View attachment 197632


Much easier to use with an FD to RF adapter  . The focus peaking and IBIS in the R5 make the lens quite usable and even hand-holdable if you are reasonably steady. Also no lens required in the adapter for infinity focus.


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## TAF (May 17, 2021)

rrdoh said:


> I still have my FD500 f8 reflex lens, works well with a cheap FD to EF adapter: sadly no AF or IS in 1985. Doesn't get a lot of use but am happy to see the possibility of new reflex/cat lenses coming.
> View attachment 197632


That is an excellent image. My I ask the exposure settings?


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## stevelee (May 17, 2021)

blackcoffee17 said:


> Oh, please no! At least those 600mm and 800mm lenses have pretty good image quality with nice bokeh. If they were mirror lenses I would just ignore them as the usage is very limited. I don't mind Canon making few mirror lenses but we need affordable high quality telephotos also.


And people these days want to shoot mirrorless.


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## slclick (May 17, 2021)

stevelee said:


> And people these days want to shoot mirrorless.


(Canon warehouse crew) "Now what do we do with all these mirrors?"
(Lens product team) "We'll take them off your hands"


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## rrdoh (May 17, 2021)

TAF said:


> That is an excellent image. My I ask the exposure settings?


1/2000 sec at ISO 1600, (f8 obviously)on a 5D4, minimal post in LR (Camera Faithful, remove chromatic aberration, clarity at 57, cropped to 4173x2348). Glad you like it


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## rtweed (May 17, 2021)

Dragon said:


> The Canon FD 500mm Cat is lighter than the Nikon and quite usable on an R5 with IBIS on. It is also pretty reasonable on fleabay.


Yes the FD 500mm f8 is very lightweight, and also works great on my M6ii. An IS/AF version would be interesting: the depth of field is wafer thin and makes photographing anything that is moving something of a challenge!


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## 20Dave (May 17, 2021)

Dragon said:


> I suspect they will be optically superior if they come to pass. AFAIK the Celestron Edge uses a spherical mirror with with a correction lens. The Canon patent distinctly shows and aspheric mirror design which should be inherently superior. In the end, it is all in the implementation, but the odds are very high that Canon will do a better job. The patent also shows a considerably more complex lens grouping than any of the conventional telescopes. Some of that will no doubt be due to the IS, but I suspect more care in correction as well.


I have a hard time thinking that it will be better in terms of image quality at infinity focus, as the Edge scopes (and most other SCT scopes) also provide flatteners and reducers which are additional lens elements to ensure a flat field over a large area. In some cases, they are designed for a flat field for sensors much larger than a full frame 35mm (e.g. the 16803 CCD which has a 52mm diagonal). See here for some amazing photos with an Edge14 and a 16803.

Where I can see possible improvements are in a few other areas:

Image stabilization. This is the biggest improvement, since telescopes assume that they are on a very sturdy mount. 
Focusing at terrestrial distances. Most SCTs do allow for reasonably close focusing, but that's not what they're optimized for.
Possibly autofocusing, but I didn't see that on the patent.


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## telemaque (May 18, 2021)

Well for people looking for high quality image with long focal; I strongly suggest Telescopes...
In fact, that lens seems to follow a Maksutov Cassegrain design and plenty of Maksutov Cassegrain Telescopes are sold at much more decent prices...
from $900 for 90mm Diameter to $2500 for 180mm Diameter.

And just to prove, I have some of these telescopes home.

Bottom Left: Questar 3.5' with Zerodur Mirror. Excellent quality. Diameter 90mm Focal 1400mm. Normal price was $4000, I paid 2nd hand €900
Top left: Perl 115*900 not the best for photography
Bottom Right: Takahashi Mewlon 210: Diameter 210mm, Focal 2200 mm. Normal price was €4000, I paid 2nd hand €1800.

And astronomers have developped ALL SORTS of adapters for any Camera body.


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## telemaque (May 18, 2021)

And the type of images a Canon 60D plus such telescopes gives:


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## telemaque (May 18, 2021)

other example with the Takahashi:

Details of the "Strait Wall".


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## telemaque (May 18, 2021)

Last but not least full Moon Eclipse: Heart of the Eclipse.
Canon 60D and Telescope triplet apochromat refractor Meade 80mm Diameter, 480 mm Focal 6000 Series. Price €1500 !


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## pape2 (May 19, 2021)

Jup always bit wondered why star telescope tech isnt used more to land lenses.
honey comb tech main mirror with 30cm diameter could be something portable actually.


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## AJ (May 19, 2021)

$50,000 for a 5200 mm f/14 sounds like a lot of money for an older design. It is in the same league as a modern telescope with similar specs. Here is a 4800 mm f/8








Officina Stellare Ritchey-Chretien RC 600/4800 Pro RC SGA OTA


PRO RCs from Officina Stellare: The choice of professionals.The advantages of the Ritchey-Chrétien telescopes are very well known. It’s the most widely used optical scheme by...




www.astroshop.eu


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## justaCanonuser (May 20, 2021)

Not sure if someone already posted it, but on youtube you can find a video about Canon's 5200mm lens:






Living in the 500-1000mm "microworld" of telephotography I ask myself if you ever will have sufficient weather conditions to get a sharp shot of something that is 30 miles away - maybe in some deserts in the morning, before thermal blur starts to kick in. This is already your true enemy with much shorter tele lenses.


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## justaCanonuser (May 20, 2021)

AJ said:


> No kidding. How on Earth would you keep a 5200 mm lens steady. That and atmospheric turbulence would be big challenges.


Keeping it steady is no problem with that mass, but obstacle #2 (blur) is the real challenge. Maybe you should move to the moon to use this lens.


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## justaCanonuser (May 20, 2021)

I wonder why nobody asked so far for which purpose Canon made this 5200mm monster - or did anyone in this thread and I missed this Q & A?


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## pape2 (May 21, 2021)

With 100m minimum focus distance wont be too much thermal blur .
And anyway astronomers use lot bigger telescopes than this , if it would be useless becouse thermal blur ,why would they bother.


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## Dragon (May 21, 2021)

s


pape2 said:


> With 100m minimum focus distance wont be too much thermal blur .
> And anyway astronomers use lot bigger telescopes than this , if it would be useless becouse thermal blur ,why would they bother


Astronomers are looking pretty much straight up whenever possible and they still fight "seeing conditions". Thermal distortion is much greater looking horizontally. Shallow angle horizontal views through thermal layers are the worst. The same rule holds for microwave siting. OTOH, just because you have a 5200mm lens doesn't mean you have to use it to photograph something 30 miles away. You can also take photos of the anthill in the neighbor's yard .


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## SteveC (May 21, 2021)

Dragon said:


> s
> 
> Astronomers are looking pretty much straight up whenever possible and they still fight "seeing conditions". Thermal distortion is much greater looking horizontally. Shallow angle horizontal views through thermal layers are the worst. The same rule holds for microwave siting. OTOH, just because you have a 5200mm lens doesn't mean you have to use it to photograph something 30 miles away. You can also take photos of the anthill in the neighbor's yard .


 Waiting for the gallery of celebrity nose hair pics.


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## mdcmdcmdc (May 21, 2021)

When were these made? I didn't see a copyright date in the scans. Looks like the kind of thing NASA would have used to follow rocket launches in the 1960's and 1970's. Or other agencies of one or more governments to follow other things.


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## pape2 (May 22, 2021)

Dragon said:


> s
> 
> Astronomers are looking pretty much straight up whenever possible and they still fight "seeing conditions". Thermal distortion is much greater looking horizontally. Shallow angle horizontal views through thermal layers are the worst. The same rule holds for microwave siting. OTOH, just because you have a 5200mm lens doesn't mean you have to use it to photograph something 30 miles away. You can also take photos of the anthill in the neighbor's yard .


My art landscape pic with RF800mm  bird looks ok


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## Dragon (May 22, 2021)

pape2 said:


> My art landscape pic with RF800mm  bird looks ok
> View attachment 197773


Did you Photoshop the background with a Monet filter or is that a combo of thermal distortion and "Monet" bokeh?


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## mdcmdcmdc (May 22, 2021)

mdcmdcmdc said:


> When were these made? I didn't see a copyright date in the scans. Looks like the kind of thing NASA would have used to follow rocket launches in the 1960's and 1970's. Or other agencies of one or more governments to follow other things.


I did some additional digging courtesy of Google and found this from 2000:



Canon 800mm f3.8 and 2000mm f11 CAT Lenses



The email reporduced there refers to a booklet dated May 1965, which is consistent with the CR article saying mid-1960's. Judging from the scans, however, it doesn't look like it's the same brochure that was posted on CR. The email above refers to them as "TV" series lenses, and indeed, the label on the 2000 mm f/11 lens in the image says "TV LENS" which is not in the scans posted on CR.

If you follow the "MORE Images..." link at that page, you'll see the 800 and 2000 mm lenses with their hard cases. Looks like they each had *two* hard cases, one for the lens and one for the hood!

I also found a couple of mentions of the 5200 f/14 saying only three were made. Seems plausible but I don't have links.


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## pape2 (May 23, 2021)

Dragon said:


> Did you Photoshop the background with a Monet filter or is that a combo of thermal distortion and "Monet" bokeh?


Thermal distortion and mirages. no filters


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## Dragon (May 23, 2021)

pape2 said:


> Thermal distortion and mirages. no filters


It is interesting (and informative to understand) how thermal distortion is localized based on terrain and airflow. layering based on elevation is the most common condition, but here you are showing clarity in the foreground with extreme distortion in the background (i.e. horizontal stratification). I am guessing there was breeze between you and the bird that wasn't present in the background. I have an EF 800L that I spend some quality time with and the conditions are ever changing and only rarely excellent. That will be a challenge for users of longer mirror lenses if Canon decided to bring them back. I have found that the mirrors seem to have less useful DOF (possibly because of the Bokeh transition) than a refractor (I also have a Nikon 1000mm Cat). Accurate AF would be a huge help in nailing focus.


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## pape2 (May 24, 2021)

Dragon said:


> It is interesting (and informative to understand) how thermal distortion is localized based on terrain and airflow. layering based on elevation is the most common condition, but here you are showing clarity in the foreground with extreme distortion in the background (i.e. horizontal stratification). I am guessing there was breeze between you and the bird that wasn't present in the background. I have an EF 800L that I spend some quality time with and the conditions are ever changing and only rarely excellent. That will be a challenge for users of longer mirror lenses if Canon decided to bring them back. I have found that the mirrors seem to have less useful DOF (possibly because of the Bokeh transition) than a refractor (I also have a Nikon 1000mm Cat). Accurate AF would be a huge help in nailing focus.


Lot of distance difference between elements too ,bird maybe 500 meter away. rocky island 1km far and big island horizont maybe 3km away. If i am thinking right islands 
Could be also 500m ,1,3km and 7km
And it was hot day away from shore was 25c and on shore maybe 15c and there was pack ice more far on sea.


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## Ruined (May 25, 2021)

If this happens, I have a feeling this is going to be like the Diffractive Optics lenses where people are like "wow, cool" at first, but over time end up ultimately disliking the tech.


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## telemaque (May 25, 2021)

AJ said:


> $50,000 for a 5200 mm f/14 sounds like a lot of money for an older design. It is in the same league as a modern telescope with similar specs. Here is a 4800 mm f/8
> 
> 
> 
> ...


 
and this Italian company is very known for high quality products. The Ritchey Chretien design gives also less diffraction on the side of the image.


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## justaCanonuser (May 26, 2021)

Dragon said:


> s
> 
> Astronomers are looking pretty much straight up whenever possible and they still fight "seeing conditions". Thermal distortion is much greater looking horizontally. Shallow angle horizontal views through thermal layers are the worst. The same rule holds for microwave siting. OTOH, just because you have a 5200mm lens doesn't mean you have to use it to photograph something 30 miles away. You can also take photos of the anthill in the neighbor's yard .


But the anthill must be 100 m away minimum. Btw modern optical telescope for astronomy use adaptive optics to restore light wave fronts distorted by atmospheric blur and get sharp images.


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## SteveC (May 26, 2021)

justaCanonuser said:


> But the anthill must be 100 m away minimum. Btw modern optical telescope for astronomy use adaptive optics to restore light wave fronts distorted by atmospheric blur and get sharp images.



Unless something has drastically changed, adaptive optics aren't found (yet) on telescopes for amateur astronomers; we are talking the big ones like the ones on Kilauea that professional astronomers may be lucky enough to get to use.


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## Dragon (May 27, 2021)

justaCanonuser said:


> But the anthill must be 100 m away minimum. Btw modern optical telescope for astronomy use adaptive optics to restore light wave fronts distorted by atmospheric blur and get sharp images.



True of the telescopes on top of Mona Kea using lasers to monitor the atmosphere, but not something you will find in a back yard telescope.


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## mdcmdcmdc (May 29, 2021)

There are so-called "adaptive optics" systems marketed for amateurs, but they're not the atmospheric compensation/mirror deforming systems used by the pro observatories. They look like they use moveable optics to rapidly compensate for smaller tracking errors than the normal autoguiding can handle. In that sense, they're more like IS for telescopes.

E.g.:








SBIG AO-8T Adaptive Optics for STT Series Cameras | OPT Telescopes


The SBIG AO-8T Adaptive Optics System is a closed loop adaptive optics system for dual sensor STT series USB cameras. Dramatically improves imaging by reducing the affects of atmospheric turbulence, vibrations, and periodic error. To us




optcorp.com









Orion SteadyStar Adaptive Optics Guider | Orion Telescopes


High-speed refractive correction eliminates tracking errors resulting in better astrophotos with rounder and more pinpoint stars. Shop online - 100% satisfaction guaranteed!




www.telescope.com


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## Dragon (May 29, 2021)

mdcmdcmdc said:


> There are so-called "adaptive optics" systems marketed for amateurs, but they're not the atmospheric compensation/mirror deforming systems used by the pro observatories. They look like they use moveable optics to rapidly compensate for smaller tracking errors than the normal autoguiding can handle. In that sense, they're more like IS for telescopes.
> 
> E.g.:
> 
> ...


Looks like something to stabilize the system for very long exposures by tracking a bright guide star. Probably does more to minimize the effect of stepper motors and wind vibration than to mitigate atmospheric effects, but it could help with the latter in some cases. It would do nothing for a typical 1/100th second (or faster) daylight exposure.


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## justaCanonuser (May 29, 2021)

Dragon said:


> True of the telescopes on top of Mona Kea using lasers to monitor the atmosphere, but not something you will find in a back yard telescope.


I should have added that I edit a German physics magazine, so what is normal for me is not normal for the average person


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## justaCanonuser (May 29, 2021)

Dragon said:


> True of the telescopes on top of Mona Kea using lasers to monitor the atmosphere, but not something you will find in a back yard telescope.


Artificial stars produced by lasers are one way of controlling adaptive optics, but not the only one.


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