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09-12-2016, 04:19 AM   #16
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The cheapest and easiest way to grind glass are the spherical shape. This is the reason curved (spherical) sensors are the optimal shape for lens designers. So its a trade off. Cheaper glass and more expensive sensors. Currently spherical sensors are far more difficult and expensive then solving the same problem with aspherical (hyperbolic) lenses. If you could solve the cost problem, then curved sensors will be the favorable choice. Lens constriction would need less compensating lens elements and be cheaper and lighter.


Last edited by Simen1; 09-15-2016 at 04:48 AM.
09-13-2016, 11:21 AM   #17
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Yeah, I think curved sensors would mostly work for fixed-lens cameras, which these days means phones and P&S compacts, WR compacts (GoPro?)
09-13-2016, 02:28 PM   #18
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09-16-2016, 04:10 AM - 1 Like   #19
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QuoteOriginally posted by Barry Pearson Quote
For "happens in body" read "in post-processing".

I'm happy to have a lens with aberrations that can be corrected well in post-processing, (for example Lightroom), if that makes it easier to design the lens for other benefits, such as cost, weight, minimised aberrations that can't be corrected in post-processing, etc.
the cost benefit is rarely passed on to the consumer otherwise the camera manufactures own brands of lenses would be cheaper than the third party ones
and yes some of us are happy to do some post processing.

QuoteOriginally posted by pjv Quote
Would a curved sensor have to " uncurve " as the lens was stopped down?
unlikely, the whole idea of curved sensors is to reduce diffraction when stopped down and vignetting when wide open

QuoteOriginally posted by Simen1 Quote
Currently spherical sensors are far more difficult and expensive then solving the same problem with aspherical (hyperbolic) lenses. If you could solve the cost problem, then curved sensors will be the favorable choice. Lens constriction would need less compensating lens elements and be cheaper and lighter.
the main problem is etching and coating a curved wafer, i imagine yields would be another factor.

09-16-2016, 01:01 PM   #20
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I suspect that even if it was best, you'd have issues with all the lens out there that are optimized for a flat sensor and field. I suspect there would be issues with the shutter mechanism in a dSLR, too. Perhaps it would need implementing in a mirrorless, or more ideally a camera with the lens built in (as others mentioned earlier).
09-17-2016, 05:17 AM   #21
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QuoteOriginally posted by emalvick Quote
I suspect that even if it was best, you'd have issues with all the lens out there that are optimized for a flat sensor and field. I suspect there would be issues with the shutter mechanism in a dSLR, too. Perhaps it would need implementing in a mirrorless, or more ideally a camera with the lens built in (as others mentioned earlier).
forget backwards compatibility, technological advancements always comes from forward thinking. the main purpose of a curved sensor is lower distortion and aberrations at ultra wide angles, think 8mm full frame equivalent field of view with near perfect flat field edge to edge sharpness from a simple meniscus lens. or a interchangeable 4 element prime lens where you only change out the front element to change the focal length, this is why some companies have patented some designs to make sure their competitors do not get the jump on them.
09-17-2016, 07:05 AM - 1 Like   #22
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QuoteOriginally posted by Ratcheteer Quote
forget backwards compatibility, technological advancements always comes from forward thinking. the main purpose of a curved sensor is lower distortion and aberrations at ultra wide angles, think 8mm full frame equivalent field of view with near perfect flat field edge to edge sharpness from a simple meniscus lens. or a interchangeable 4 element prime lens where you only change out the front element to change the focal length, this is why some companies have patented some designs to make sure their competitors do not get the jump on them.

Not as simple as you make it out to be. The curvature needed for an ultra wide angle lens would be different that needed for even a 28mm or 50mm lens. The image curvature is lens dependent. What curvature would be the best across the potential range of lenses that could be used on a camera?

To me, UWA lenses are pretty much toy lenses. I can go to 12mm on my K3 and 18mm on my K1 and that is about all I will ever need. If you want distortion free ultra wide angle images just use a normal lens, pan it and stitch the images together in post processing.

The supposition that a simple meniscus lens is all you would need is not true. Even with a curved sensor, there are a lot of aberrations that would still exist. That is why multiple lens elements are needed. Chromatic aberration is not solved by a curved sensor. Purple fringe would still be a something to deal with too. Image resolution would be pretty bad In the ancient days when most people had cameras that used 120 or 620 film, or larger, the first lenses were doublets. These were superseded by triplets which have a very pleasing quality to them but are still not tack sharp. Work fine with B&W film. Then the four element lens came into being for these cameras and they performed so well that people were not sure they liked added sharpness. Especially in portraits.

Then people went to 35mm format and these same lenses do not perform well at that format. Simple rule. The larger the format, the lower the quality of the lens needs to be. Or a small format camera requires a high resolution lens. And the modern "full frame" camera is still a small format camera. No simple lens is ever going to perform that well on a small sensor camera even if the sensor is curved.
09-17-2016, 08:53 AM   #23
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QuoteOriginally posted by gaweidert Quote
Not as simple as you make it out to be. The curvature needed for an ultra wide angle lens would be different that needed for even a 28mm or 50mm lens. The image curvature is lens dependent. What curvature would be the best across the potential range of lenses that could be used on a camera?
who cares its the registration distance that dictates the curvature anyways, the thinking process behind mirrorless was shorter back focus distance so why not make the curved sensor register distance variable to cater for fine tuning

QuoteOriginally posted by gaweidert Quote
To me, UWA lenses are pretty much toy lenses. I can go to 12mm on my K3 and 18mm on my K1 and that is about all I will ever need. If you want distortion free ultra wide angle images just use a normal lens, pan it and stitch the images together in post processing.
sure if your subject is still and you have all the time in the world and there is no chance it will rain, some of us want to travel and leave the tripod and computer at home

QuoteOriginally posted by gaweidert Quote
Chromatic aberration is not solved by a curved sensor. Purple fringe would still be a something to deal with too.
its already been proven that it does work and fringes what ever the colour are not a problem cause the curvature ensures that the focused wavelengths or light hits the sensor at the optimum distance/focal point to reduce wavelength separation which normally causes color bleed known as fringing in areas of high contrast.

when you start adding more elements you start reducing the quantity of light, and the sharpness that people did not like from the 4 element tessar design was it had a undesirable effect on out of focus areas/bokeh/highlights it was distracting.


Last edited by Ratcheteer; 09-17-2016 at 09:14 AM.
09-17-2016, 09:01 AM   #24
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A curved sensor might be great for a fixed-lens camera (e.g., Sony's KW1 or the Kepler space observatory) but as others point out, it's not going to help with interchangeable lens cameras in which lenses of every focal length except one would need "expensive" corrective elements to match the native field curvature of that focal length to the sensor's curvature.

Two other trends seem to imply that curved sensors are unlikely to ever be that useful. First, looking at recent lens designs, it's clear that lens makers are getting better and better at making complex curved elements with low light-loss coatings at ever lower prices. In contrast, curved silicon of any decent size looks really expensive. Second, advances in digital signal processing (and high-DR sensors) can all but eliminate vignetting, geometric distortions, and even various sources of blurring. So a curved sensor DSLR system is likely to cost more but not deliver more in the final image.
09-17-2016, 09:51 AM   #25
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QuoteOriginally posted by gaweidert Quote
No simple lens is ever going to perform that well on a small sensor camera even if the sensor is curved.
you think that because of what the past tells us, but back then they didn't have computer aided design and nano coating that not only increases light transmittance and removes reflection but repels water/moisture and dust, glass manufacturing has changed by removing the human element glass is now manufactured in higher temps cleaner environments and handled less and made by precision machining to tighter tolerances not possible by the methods of the old.

the best bit is the lens can be made alot thinner and smaller with even shorter back focus, the idea is not to make it better but make things smaller and give us more options - imagine a cellphone that can take distortion free vignette free sharp edge to edge 8k video
09-17-2016, 04:12 PM   #26
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Many of us know the basics of optical design, but I wonder just how many have actually put it into practice. Some input from people who make their living from it might be useful, and not filtered through the self-interest of a manufacturer with an axe to grind.

Given the number of lower-cost lens manufacturers coming onto the market in recent years, the benefits of computer-aided design (in ray-tracing, as well as manufacturability and structure) in reducing cost are obvious. That phenomenon alone reduces the benefit of changing the sensor design from a flat to a spherical surface, and further reductions in the cost of lens design and manufacture would have to outweigh the additional cost of changing the sensor design.

In addition, as others have noted, the radius of curvature of the sensor surface would either have to be flexible, to maximise the benefit in an ILC, or a compromise over a range of focal lengths that I suspect would, in turn, have a complicating influence on the design of suitable lenses. The economics would have to be studied in detail, to work out if there was an overall reduction in cost, and I'd guess some manufacturers would be doing just that, right now. That, itself, is probably a major reason for the delays in the annoucements of the Sony and Nikon cameras that were supposed to be available right now - nobody would be willing to make such a gamble in the present market conditions, without being certain of the outcome. Ten years ago, Sony probably would have thrown a couple of bodies out already, but things have changed.
09-17-2016, 08:40 PM   #27
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The economics of the camera industry now probably make changing to curved sensors for ILC not pheasible.

While computer aided design is better and cheaper than ever, lens companies benefit from designs that tweak what is already available. A curved sensor would require a significant change to every single lens being manufactured. And of course if the curve is fixed, it wouldn't really be a benefit to anything but a few focal lengths that the curve complements well, which I would argue is exactly the same as what we have now. The only difference I see is that curves would / could benefit wide angle photography more than a flat sensor does now (while potentially hurting the telephoto quality, which I suspect benefits more from a flat sensor).

I also suspect that from a optics perspective that it is easier to bend light towards a flat surface than it might be the other way. I suppose it might be just a case of changing some elements from convex to concave or vice-a-versa.

However, as suggested, it could be good for phones and other single-lens-cameras. But, who knows what the cost of manufacturing a curved sensor will be versus any savings on the lens side.
09-18-2016, 03:21 AM   #28
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If curved sensors are worth doing they'll have been done already in military reconnaissance or space applications. If so, it's just a matter of time before they appear in civilian applications.
09-18-2016, 03:28 AM   #29
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QuoteOriginally posted by RobA_Oz Quote
Many of us know the basics of optical design, but I wonder just how many have actually put it into practice.
military and pin hole enthusiasts
they have been curving film along the petzval field plane for years

QuoteOriginally posted by emalvick Quote
I also suspect that from a optics perspective that it is easier to bend light towards a flat surface than it might be the other way.
thats if all light were equal, but its not its a spectrum (a condition that is not limited to a specific set of values but can vary infinitely within a continuum)

for every element you add to correct one aberration, that element introduces another aberration, this is why modern prime lenses can have upto 11+ elements and cost more than most camera bodies

*** just been talking to a guy who actually curved a canon 400d sensor, but it was de-Bayered first (he was using the camera for astro and infrared photography before this experiment)

he said it actually improved the wide open performance and edge sharpness on the entire focal range of a 15-85 efs lens, his conclusion was that it will likely work so well that it might cause some companies to pull out of the camera market altogether due to patients and licensing fees.

Last edited by Ratcheteer; 09-19-2016 at 09:31 AM. Reason: new information
09-19-2016, 07:14 AM   #30
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QuoteOriginally posted by Ratcheteer Quote
you think that because of what the past tells us, but back then they didn't have computer aided design and nano coating that not only increases light transmittance and removes reflection but repels water/moisture and dust, glass manufacturing has changed by removing the human element glass is now manufactured in higher temps cleaner environments and handled less and made by precision machining to tighter tolerances not possible by the methods of the old.

the best bit is the lens can be made alot thinner and smaller with even shorter back focus, the idea is not to make it better but make things smaller and give us more options - imagine a cellphone that can take distortion free vignette free sharp edge to edge 8k video
What you you say here is very true and exactly why curved sensors are not very likely. It's now much easier to design and manufacture a complex lens for a flat sensor than ever before. Add faster GPUs and CPUs to the mix (required in the device anyway for all the fun little filters that people want to apply to their images) and there's no reason you can't have "distortion free vignette free sharp edge to edge 8k video" with a cheap flat sensor, cheap (but complex) lens, and software.
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