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Researchers create focus-free camera with new flat lens
- deleted 7y ago[deleted]
- css 7y agoA lens that keeps everything in focus (aka, large or infinite depth of field) is not desirable for most photography applications; this mainly has important implications for industrial use. It is always interesting to see innovations in this space.
- narrowtux 7y agoI'd be interested if this lens would transmit more light than a traditional lens stopped down to f/13 and focussed to hyperfocal distance. If that's the case, it could find application in photography for low-light photography.
- glitchc 7y agoNot sure I understand this statement. The depth of field spans a distance both in front and back of the focussing range where all objects are in equivalent focus. To focus all objects of interest spanning a set of ranges, the appropriate approach is to focus on an element roughly in the middle of the set, then increase the depth of field until all elements are in roughly equivalent focus. One does not focus at the hyperfocal distance and step everything down. If all objects are at or beyond the hyperfocal distance, one can focus the lens to infinity and be done with it. All objects will remain in focus regardless of the size of the aperture as all rays incident on the lens from a given object are quasi-parallel. EDIT: Quasi-parallel from the object, not quasi-parallel to the optic axis.
- narrowtux 7y agoHyperfocal focus distance can be achieved with lower focus distances than infinity, see this table: https://www.photopills.com/calculators/hyperfocal-table https://www.photopills.com/calculators/hyperfocal-table It depends on the focal length, the chosen aperture, and to some extent on the resolution of the camera. What I want to say is, if these new lenses transmit light at a high rate (let's say 1:2.8) while being hyperfocal from 0 mm to infinity all the time, you could take pictures at night more easily without having to focus or stop down to get larger scenes fully in focus. Thus being actually useful in traditional photography. Landscape photography could be another application.
- zxcmx 7y agoCan you explain more about this? I've seen a few startups now pitching depth-of-field innovations for biometric use. For example http://www.infinityoptics.com.sg/who-we-are/ http://www.infinityoptics.com.sg/who-we-are/ Not sure if this is a bit too directly commercial for HN, asking re: optics not the whole solution. Assuming a celllphone-ish sensor in terms of scale and cost (assuming lenses are free) how well can one do in theory? Particularly for iris? How feasible is it to have iris scanners we don't need to shove our faces into?
- altcognito 7y agoSoftware can fill in many of the gaps required for photography.
- glup 7y agoA common opinion among software engineers, but less common among serious photographers. "Portrait mode" looks like a cheap instagram filter. To be fair, it does let a much larger population experiment with effects that otherwise take a bit of specialized gear and knowledge.
- jayd16 7y agoWe can just make a lens that's unfocused at every depth and merge the two as needed. Joking aside, I wouldn't doubt this creeping into the film industry or other professional photography. Everything already goes through so much post processing, color correction, etc etc.
- ansgri 7y agoModern phones get you 90% there. The bokeh quality apparently wasn't a priority until very recently. For indoor applications, a Huawei P20 Pro with artificial bokeh and good onboard image processing beats my APS-C-format Sony camera with an F/1.4 lens most of the time — not even counting cases when the depth of field of said F/1.4 is too shallow! No way can that mobile thing compete with a good lens in good lighting though. But soon that won't be because camera hardware isn't competitive; rather, the phone's computational photography pipeline and lack of dedicated controls wouldn't allow enough flexibility in shooting techniques. Again, the mobile phone manufacturers are just starting advancing to higher-end photography — the science and computing power is basically there, you can do a lot with deep learning combined with real understanding of image formation and photography. I wouldn't call myself anything serious as a photographer; OTOH some serious photographers whom I follow start turning more into 3D artists or videographers. Photography as a profession seems to be in a crisis: not that it's not needed, it's that many adjacent things (3D, video, design, marketing) are also needed, not unlike in programming: there's almost no such thing as a senior (e.g.) Python developer, there are senior Web, Data, etc. developers which primarily use Python along with other tools (JS, sql, etc).
- Obi_Juan_Kenobi 7y ago> is not desirable for most photography applications Hardly. It's namely portraiture that benefits from thin DoF, or similar applications where figure/ground relationship can be improved by keeping OOF elements blurry. There are a great variety of situations where you do want as much in focus as possible. Landscape and macro photography are the most notable examples, where most high-level images utilize focus-stacking composites to simulate extreme DoF. Certainly focus depth is a creative tool, but don't confuse expensive wide-aperture lenses for what is necessarily good.
- branko_d 7y agoCould this be used for glasses? Could the same glasses serve both as reading glasses and as long-distance glasses?
- warkdarrior 7y agoNo, unless you replace your eyes with chips that perform the post-processing of the image.
- intpx 7y agoor use EVFs or hybrid EVF/OVFs in place of you glasses lenses. Could conceivably allow for AR glasses that would facilitate telescopic capabilities, once a million other roadblocks are overcome.
- rini17 7y agoBrain could certainly learn to do it :)
- red75prime 7y agoMaybe it can, but it doesn't do a thing. At least for me. Deconvolution of astigmatic eye lens image? Nope. Spatial superresolution by temporal integration? Nope. Low-level visual processing in our retinas and brains seems to be too specialized to learn new tricks.
- rini17 7y agoThe brain does all the time spatial superresolution by temporal integration! Look up "saccade". No idea about deconvolution, but I doubt computers can do better job identifying things from blurry images than brains.
- red75prime 7y agoSaccades are just compensation for low peripheral resolution and shortcomings of rods and cones. I had in mind getting more resolved images than what number of photoreceptors allows.
- jfengel 7y agoIt sounds like kind of a cross between a light-field and a fresnel lens. It uses the shape of the surface to make patterns on the chip, and which then has to be decoded with a lot of processing. Instead of microlenses on the chip you put microlens-replacements in the flat surface.
- econcon 7y agoDid someone ever use electromagnetic diaphragm to control lens shape?
- banana_giraffe 7y agoI think you're referring to so called electrically tunable lens. Most every camera these days uses an electromagnetic diaphragm to control the aperture. And yes, it's a electrically tunable lens are a thing. Optotune is one company I've heard of making hardware for the industrial space, there are probably others.
- hatsunearu 7y agomany mini cameras use either liquid lenses or voice coil lenses to focus.
- jungletime 7y agoThis seems like it would increase the distance that you need to hold the phone to take a selfie. And won't have Bokeh. Bokeh is the effect of blurring out the background. Its important because it lets you isolated the subject, like a human face, from the background. Still, if it does one thing better than other lenses, it will be useful.
- JangoSteve 7y agoBut isn't the problem with isolating parts of the image at the optical level that you can't later undo it? It seems like at least one of the advantages to everything being in focus is that you can isolate whatever you want in post-processing. Cameras are already doing this, they just require multiple lenses and thus more space and material to do it.
- mech1234 7y agoBokeh is both a feature and a bug. I kinda figure if cameras never had bokeh we would never miss it.
- narrowtux 7y agoInteresting thought, if cameras (and generally optics) wouldn't have bokeh, our eyes wouldn't have to focus either and wouldn't have bokeh in unfocussed areas as well. In that case, we truly woulnd't miss it.
- penagwin 7y agoWell like the others said, bokeh != Depth of field. That said even if you removed all depth of field (everything is in focus somehow) it would still be missed. Depth of field is incredibly important for managing a viewers focus. Imagine a picture of a coffee in a coffeeshop with the background out of focus - you can clearly see a coffee cup. That same photo but with everything in focus will be much more confusing - what should I be looking at, it's too busy, etc.
- ska 7y agoBokeh is the effect of blurring out the background. This is slightly incorrect in an important way. Depth of field has the effect of blurring out the background and/or foreground; it is a property of optical systems. However, the design of lenses changes how this looks. The latter part is what "bokeh" means, and it is why people talk about "the bokeh" of a particular lens. In other words, bokeh is fundamentally an aesthetic characteristic.
- glitchc 7y agoThey are probably experimenting with sandwiches of high refractive index material. There are no statements regarding transmissivity, which leads me to believe that its actually lower than a typical lens wide open i.e. the incident irradiance (light on the sensor) is equivalent to a regular lens set to a narrow aperture. There is no free lunch in optics or physics usually.
- kragen 7y agoThe abstract: https://www.osapublishing.org/optica/abstract.cfm?uri=optica-7-3-214 https://www.osapublishing.org/optica/abstract.cfm?uri=optica... The paper: https://www.osapublishing.org/optica/viewmedia.cfm?uri=optica-7-3-214&seq=0 https://www.osapublishing.org/optica/viewmedia.cfm?uri=optic... I've only skimmed it, but it looks super interesting. I was expecting some kind of computational holography wizardry, but no, it's just a multilayer diffractive lens with circular symmetry which produces a beam with a really stretched-out waist. Usually diffractive lenses are limited to a single wavelength — they're using 850 nm. Is there a way something like this can work over the whole visible spectrum? If not, this might be more like a lightsaber than a camera.
- roosterdawn 7y agoEven if it doesn't work over the whole visible spectrum, is there any way that this could be used in some way that is sort of like an inverse ink jet printer where half-toning is used with a couple basis wavelengths to simulate the whole color spectrum? Am I basically just describing something similar to an LED screen but in lens form?
- kragen 7y agoMaybe! You'd be sacrificing most of the light, though.
- hatsunearu 7y agomight be good enough for machine vision applications with a narrow bandwidth LED or something like that. I'm guessing light that's not exactly at that wavelength will cause additional blurring.
- neurostimulant 7y ago> Conventional cameras also use multiple lenses to keep different colors of light in focus simultaneously. Since our design is very general, we can also use it to create a single flat lens that focuses all colors of light, drastically simplifying cameras even further. Not sure if they already have a full-spectrum version working though.
- anovikov 7y agoSomeone just reinvented the Fresnel lens?
- kazinator 7y agoScrew phone cameras; help people with visual impairments see better! Phone cameras are already twice as good as they need to be.
- ska 7y agoThere is nothing phone-camera specific about this idea, the (lay) article just uses that as an example of "conventional camera". Visual impairments is pretty broad, and this approach is using collimated light so not general purpose - but things in this direction could plausibly have applications in the area.
- dantheman 7y agoIf these get in phones they'll help people with visual impairments way more and at a much lower cost.
- tal8d 7y agoWhich market will bring costs down and feed into the next cycle of development, a market that potentially includes everyone - or a market restricted to desperate legally blind people? I'm not a fan of consumerism, but it goes a lot further in improving the lives of everyone, versus conspicuous virtue projects.
- tardo99 7y agoSorry for the downvotes. I'll get downvoted too bc of my username. I agree with your point. Instagram is evil.
- dcanelhas 7y agoA pinhole camera is also focus-free :)
- aj7 7y agoShow us ONE image.
- barbegal 7y agoDepth of field for a normal camera is a function of the relative aperture size (f-number), focal length and distance to the subject. This camera is able to create a huge depth of field with a far smaller aperture than would be expected with a conventional camera. So how does it break the laws of physics? Well it doesn't; it cheats by not preserving the phase of the light. In a normal lens, the phase of the light is preserved. Light that must travel further to reach the point of focus travels faster as it passes through less lens material (where it travels slower than the speed of light). The lens is also made on a flat disc a little bit like a Fresnel lens. The difference with this lens is that it doesn't have a single point of focus, instead light is focused onto many planes, simultaneously with equal power of light focused onto each plane. In this paper the planes were chosen to be between 5 and 1200mm. A clever computer algorithm calculates the exact shape of the lens to get this distribution given a specific wavelength of light. The end result is a lens which has amazing depth of field but the trade off of only operating well at a single frequency and poor efficiency. Most of the incoming light is being focused on a plane that the sensor isn't on. Indeed at 1200mm it has an equivalent f-number of 555 requiring some insanely bright lighting and long exposure time to get a good image. I can't see many real world applications of this camera given the downsides but in a world of more computational photography this could be one part of a better imaging system.
- pedrovhb 7y agoThanks for the understandable breakdown. This is very interesting indeed, but at an equivalent f/555 I don't see many practical applications for this either. For context, usual photography uses apertures from f/1.2 to f/11, with lower numbers letting being a larger aperture and thus more light in. It'd require a massive amount of light to get a usable image. Maybe the images could be sharper with this lens, or have very good macro? As you stop down (increase the aperture number) images become sharper up to a point where the diffraction limit steps in and quality degrades; usually this happens at f/9 to f/11 (which is why I mentioned f/11 as the lower range of commonly used apertures; although almost all lenses can go smaller, for pixel-peeping quality you'd want to use an ND filter and f/11 aperture).
- blattimwind 7y agoWondering how diffraction applies to this one. Certainly not to the equivalent aperture, because any f/555 lens would resolve essentially nothing (probably measured in mm/lp, not lp/mm; edit: not quite, about 3.5 lp/mm).