Patent: Canon is actively developing fast mirror lenses

entoman · 2023-01-29T16:56:21+0000

Fischer said:
With software being able to manipulate OOF areas better and better it is not unthinkable that a software solution can "do away" with the donuts.

For these wide-aperture cats to be worthwhile for "normal" photography, they'll need to have a means of increasing depth of field, and that means having a physical aperture stop-down. The donut effect would vary considerably according to aperture, focal length and subject distance. Consequently the AI correction software would need to recognise different diameters of the "donut hole", and account for different donut diameters and different degrees of donut overlap.

Perhaps suitable post-processing software might appear in 10 years time, but I don't think it's anywhere on the horizon yet. Maybe something that NASA or the military might have, but not the general photographic community.

My guess is that if Canon is "actively developing fast mirror lenses", they won't be general sports/wildlife lenses, but are more likely to be for astro or satellite use, where depth of field is less critical due to the much greater subject distances. I'd also guess that the donut effect will be less of a problem, although the astrophotography guys here would be in a better position than I am to answer that one.

TAF · 2023-01-29T17:54:35+0000

MihalyLaczko said:
Tripod is not an option for a contrail or even for a long distance aircraft photography, due to the very narrow field of view, combined with the realtive position of the target and the relatively fast moving target. Just imagine to make a photo with 2000mm about a continously moving airplane, what you have to find by your own naked eye first. A video pan head has its own initial angle limitation, which is really slows down the reaction time. Previously, I made a photo about the ISS with the single f/10 1000mm mirror lens, handheld, because of the position of the object (right above my head, on the Zenith). So these circumstances are not really god for a tripod-related photography. I also tried a monopod, but was not so helpful at all. The slowest shutter speed ever was 1/640, but the finest sweetspot is around 1/1000 - 1/1250, depending on the actual relative angle and position of the path of the aircraft. And the shutter speed is crucial, since the reflex mirror has a lack of sharpness, combined with a really narrow depth of field. And the fact, that you could rotating over the infinite distance mark the tube, you could easly miss the right focal point. By a native 1000mm mirror focal length (the extenders are really does not matter) the depth of field is extremly narrow, so between an 1000 or an 1500 meter, I have to set the focus, with the possibility of the overrotating.

I'm curious. How do you deal with atmospheric turbulence, haze, and defraction?

I do OK in winter, but the rest of the year the air is too 'cruddy' to get a decent image.

I am presently experimenting with the RF 600mm/f11, as a replacement for the 500mm/f6.3 mirror tele (a cheap Opteka) I was using. The bokeh is much better, but the air still isn't very clear.

entoman · 2023-01-29T21:10:55+0000

TAF said:
I'm curious. How do you deal with atmospheric turbulence, haze, and defraction?

I do OK in winter, but the rest of the year the air is too 'cruddy' to get a decent image.

I am presently experimenting with the RF 600mm/f11, as a replacement for the 500mm/f6.3 mirror tele (a cheap Opteka) I was using. The bokeh is much better, but the air still isn't very clear.

With long focal lengths, atmospheric haze and heat haze can cause a lot of image degradation, regardless of the subject matter. The best time to shoot is very early in the morning, when temperatures are still low. After rain, the air is usually at its clearest.

AJ · 2023-01-29T22:07:06+0000

I'm really surprised that Canon is looking at mirror lenses.
The main advantage of mirror lenses is the short physical length due to the collapsed optical path.
However, Canon has already solved this a different way with the 600/11 and 800/11 - a way that does not result in funky bokeh.
I wonder if the same design principles of the 600/11 and 800/11 could be applied to a shorter focal length with an aperture larger than f/11.

scottburgess · 2023-01-30T04:11:13+0000

Dealing with bokeh and aperture concerns is actually pretty simple: build the lens in a Z configuration [it increases the size of the housing and looks non-standard, but who cares?]. While these patents illustrate the common ring configuration, arranging in a double barrel fashion, larger on top, allows for no ring bokeh and an aperture in the lower barrel. One might even engineer in a Canon 52mm drop-in (er, push-up?) filter. Such a lens could still be fat, but also short and light.

The important question to me is whether adequate IQ can be delivered. I would not be shocked if Canon has engineered some improvements to mirror lens technology. But as the target market for the displayed design is more likely middle-class amateurs, IQ could be similar to the mediocre 800/11 with ring bokeh added, but with a price around $1,000. It's not an unreasonable tradeoff for a casual hobbyist. I would be more interested in looking at a Z-design, short, durable, pro-quality 1000/5.6 based on the equipment I already have.

I'm guessing Canon is pulling out all their design ideas to create hardware for younger photographers in an effort to build up their amateur market. Some percentage of those will eventually become more serious or get GAS, or both.

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Patent: Canon is actively developing fast mirror lenses

entoman

wildlife photography

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TAF

EOS RP

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entoman

wildlife photography

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AJ

EOS R

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scottburgess

Canonical Canon

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