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

blackcoffee17

EOS RP
Sep 17, 2014
676
841
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

EF 800L
May 29, 2019
498
465
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

EF 800L
May 29, 2019
498
465
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

EOS RP
CR Pro
Feb 26, 2012
461
147
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?
 

stevelee

FT-QL
CR Pro
Jul 6, 2017
2,114
826
Davidson, NC
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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May 15, 2021
2
3
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

EOS M6 Mark II
CR Pro
Jan 19, 2013
75
64
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.
 

telemaque

Before Sunset
CR Pro
Nov 30, 2019
121
77
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.

EricMatos2.jpg
 
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pape2

EOS 90D
Mar 19, 2021
117
147
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.
 

AJ

EOS RP
Sep 11, 2010
730
140
$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
 
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justaCanonuser

Grab your camera, go out and shoot!
Feb 12, 2014
841
692
Frankfurt, Germany
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.
 

justaCanonuser

Grab your camera, go out and shoot!
Feb 12, 2014
841
692
Frankfurt, Germany
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.
 

pape2

EOS 90D
Mar 19, 2021
117
147
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.
 

Dragon

EF 800L
May 29, 2019
498
465
s
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 :).