HumanTarget

Lives in United States United States
Joined on Jan 11, 2011

Comments

Total: 60, showing: 41 – 60
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In reply to:

Karroly: You forget to say that increasing the diameter of the "tubes" is like waiting longer under the rain : this will increase and make more equal the number of raindrops caught by each tube, thus reducing the "signal-to-noise" ratio. For sensors, it means, putting aside electronic noise, bigger pixels will catch more photons and average the random nature of light you are talking about here.

This is why, given the same resolution, a big sensor with big pixels will ALWAYS be better in (extremely ?) low light than a small sensor, even though there were no electronic (or thermal) noise at all...

However, in practice, the true question is, and your article does not give an answer, under which pixel size and scene brightness, does a pixel catch too few photons so that the difference between adjacent pixels becomes noticable ?
Is this "noise" greater or smaller than the electronic or thermal noise ?
In other terms, do we really have to care with the random nature of photons with today sensors ?

"So combining pixels with the small sensor will decrease the resolution compared to the big sensor... And comparing the noise level of two pictures that do not have the same resolution, in other words the same level of details is just nonsense."

That makes no sense. So if a new camera model has increased resolution, it's nonsense to compare it to the previous model? Do you always view/print images in proportion to their resolution? You never resize images for a particular output?

Link | Posted on Apr 30, 2015 at 13:57 UTC
In reply to:

Karroly: You forget to say that increasing the diameter of the "tubes" is like waiting longer under the rain : this will increase and make more equal the number of raindrops caught by each tube, thus reducing the "signal-to-noise" ratio. For sensors, it means, putting aside electronic noise, bigger pixels will catch more photons and average the random nature of light you are talking about here.

This is why, given the same resolution, a big sensor with big pixels will ALWAYS be better in (extremely ?) low light than a small sensor, even though there were no electronic (or thermal) noise at all...

However, in practice, the true question is, and your article does not give an answer, under which pixel size and scene brightness, does a pixel catch too few photons so that the difference between adjacent pixels becomes noticable ?
Is this "noise" greater or smaller than the electronic or thermal noise ?
In other terms, do we really have to care with the random nature of photons with today sensors ?

"If pixels where combined, that would negate the advantage of increased pixel count as it would decrease resolution."

True. But you cannot get more detail out of bigger pixels in good light, and you can perform smarter noise reduction algorithms than simple averaging.

"Also, each pixel is amplified individually in the sensor and it's this first amplification step that contributes the most to the sensors SNR."

Which is why I said "as long as the noise is scaled adequately." Every generation of technology has a sweet spot.

Link | Posted on Apr 29, 2015 at 01:43 UTC
In reply to:

Karroly: You forget to say that increasing the diameter of the "tubes" is like waiting longer under the rain : this will increase and make more equal the number of raindrops caught by each tube, thus reducing the "signal-to-noise" ratio. For sensors, it means, putting aside electronic noise, bigger pixels will catch more photons and average the random nature of light you are talking about here.

This is why, given the same resolution, a big sensor with big pixels will ALWAYS be better in (extremely ?) low light than a small sensor, even though there were no electronic (or thermal) noise at all...

However, in practice, the true question is, and your article does not give an answer, under which pixel size and scene brightness, does a pixel catch too few photons so that the difference between adjacent pixels becomes noticable ?
Is this "noise" greater or smaller than the electronic or thermal noise ?
In other terms, do we really have to care with the random nature of photons with today sensors ?

"You forget to say that increasing the diameter of the "tubes" is like waiting longer under the rain : this will increase and make more equal the number of raindrops caught by each tube, thus reducing the "signal-to-noise" ratio."

I think you mean increasing the signal-to-noise ratio?

"This is why, given the same resolution, a big sensor with big pixels will ALWAYS be better in (extremely ?) low light than a small sensor, even though there were no electronic (or thermal) noise at all..."

But there are more of the smaller pixels, so they can be combined, thus negating the big pixel advantage as long as the noise is scaled adequately. Smaller pixels just give you more detailed data to work with.

"Is this "noise" greater or smaller than the electronic or thermal noise ? In other terms, do we really have to care with the random nature of photons with today sensors ?"

In modern sensors, yes, in all but the lowest of light levels shot noise is the dominant factor.

Link | Posted on Apr 28, 2015 at 19:28 UTC
In reply to:

junk1: Have manufacturers confirmed that signal levels (pixel size) are so low that randomness in the number of photons is noticeable?

I've always thought of larger sensors as capturing a larger signal, therefore hiding the electronic noise (and any other sources of noise), but how do we prove where the noise comes from (shot versus electronic).

Well, there's still some room for improvement in both areas. And the color filter makes for a pretty big performance hit, though there has not yet been a viable alternative. But even with a perfect sensor, shot noise is going to be a major factor at low light levels.

Link | Posted on Apr 27, 2015 at 18:50 UTC
In reply to:

junk1: Have manufacturers confirmed that signal levels (pixel size) are so low that randomness in the number of photons is noticeable?

I've always thought of larger sensors as capturing a larger signal, therefore hiding the electronic noise (and any other sources of noise), but how do we prove where the noise comes from (shot versus electronic).

Pixel size does not really matter in regards to shot noise, the total amount of light does.

Manufacturers don't always give the details of their sensors, but there are people (many on this site) who do thorough testing to determine the electronic noise. In modern sensors, it's extremely low, and so shot noise is the dominant factor of noise in most circumstances.

Link | Posted on Apr 27, 2015 at 16:57 UTC
In reply to:

ihv: Weird, CCD for aerials? Aren't shutter speeds more critical i.e. higher ISOs are more desired? CCD goes barely ISO400-800.

CCD does not mean a global shutter, nor does CMOS mean no global shutter.

Link | Posted on Apr 2, 2015 at 13:26 UTC
In reply to:

ihv: Weird, CCD for aerials? Aren't shutter speeds more critical i.e. higher ISOs are more desired? CCD goes barely ISO400-800.

Why not?

Link | Posted on Apr 1, 2015 at 12:42 UTC
On article CP+ 2015: Canon shows off prototype 120MP CMOS sensor (250 comments in total)
In reply to:

xoio: "Canon is claiming it has a pixel count equivalent to the number of photoreceptors in a human eye."

A BS publicity comment...
But it has already been widely calculated that for an image sensor to be equivalent to a human eye, it will have to be around 576 Mega pixels.
Granted not all is used at the same time though.

What does "widely calculated" mean?
And the human eye doesn't really work like a camera, so it's hard to compare; that 576MP number assumes equal detail from all portions of our vision, which isn't right. I've even seen estimates that the detailed portion of our vision is comparable to about 7MP.

Link | Posted on Feb 13, 2015 at 14:44 UTC
On article Canon announces five PowerShot compacts (146 comments in total)
In reply to:

WT21: I don't care at all about these, but it caught my eye that the ELPH160 and 170 are using CCD sensors?? What is that getting Canon? I'd almost think they were old sensors lying around, but at 20MP, they sound like new development. Of course, the limitation is immediately evident with movie mode of only 720 (maybe it's an avi file type?) Is there much upside to using CCD this day and age?

That caught my eye, too. 20MP CCD's doing 720p are at least two years old, so it wouldn't surprise me if Canon bought up some leftover sensors from some other manufacturer.

Link | Posted on Jan 5, 2015 at 16:53 UTC
In reply to:

Albino_BlacMan: How long of an exposure do you need at 0.005 lux. Isn't that an imperative piece of information?

I assume some of the better sensors out there can capture some kind of image at that level if you leave the shutter open long enough.

f/1.4 at 30fps.

Link | Posted on Oct 21, 2014 at 01:32 UTC
In reply to:

Photato: I'd be more than happy with a Smartphone having this sensor and the proper IR filter. Ok maybe 1/1.7" type with 2MP. Really interesting, I wonder how big are the pixels. Maybe equal to a FF sensor? Is that stated somewhere?

I've seen elsewhere that the pixels are 3.75um.

Link | Posted on Oct 21, 2014 at 01:16 UTC
On article What is equivalence and why should I care? (2469 comments in total)

Good article, and your work is appreciated. One correction, however: diffraction does depend on the f-number (f/16 will have the "same" diffraction softening at any focal length), but also on sensor size (diffraction softening is magnified on smaller sensors, since they must be magnified more than larger sensors). Small pixels are not "more prone" to diffraction. Pixel size has no bearing on diffraction whatsoever.

Link | Posted on Jul 7, 2014 at 15:30 UTC as 470th comment
In reply to:

vadims: I think it's about time for ISO to introduce another, logarithmic scale for measuring sensor sensitivity. The fact that the numbers look crazy does not mean that the sensitivity per se is "crazy" -- it's still far cry from the capabilities of the human eye.

BTW, "who needs more than ISO 6,400" sounds to me suspiciously similar to "640 kilobytes should be enough for everyone".

ISO DOES have a logarithmic scale (based on the DIN scale), it's just usually left out. Perhaps it'd be a good time to start using it.

Link | Posted on Jun 23, 2014 at 13:37 UTC
On article Hands on with the Pentax 645Z (705 comments in total)
In reply to:

Simon97: What are the advantages of the larger sensor? Some I can think of:

Larger Pixels for low noise. The old 645D wasn't that impressive at high ISOs, but this new sensor sounds very interesting.

Smaller DOF for artistic effects. Hopefully Pentax designed the new lenses carefully concerning Bokeh quality.

Smaller apertures before diffraction blurring is noticeable.

Probably others I'm not thinking of.

Pixel size tells you little about a sensor's performance. Sensor size and how the pixels are designed matter more. After all, what good is a big pixel if its noise is proportionately more than a smaller pixel?

And if you check out comparable 35mm lens apertures, the medium format lenses don't really offer any shallow DOF advantage.

But in addition to the diffraction advantage, you also get better performance overall from lenses, as defects aren't "magnified" so much.

Link | Posted on Apr 15, 2014 at 15:09 UTC
In reply to:

plevyadophy: This is a stupid move for a medium format cam maker. Whilst CMOS sensors offer higher ISO settings, CCD sensors are BY FAR superior in image quality at low to moderate ISO settings and medium format should be about quality and NOT bragging rights on a spec sheet.

Hassy would have been better employed commissioning Sony to use their talents to design an improved CCD sensor.

First Hassy buy discontinued Sony cams and pimp them up and sell them at silly prices and now this CMOS thing. It's really sad to see what Hassy is becoming .................. a shadow of its former self.

I hope Phase One ignore this spec sheet CMOS bragging rights nonsense and stick to CCD sensors

Medium format technology has never been THE best. Their large size has been able to mask their shortcomings, but their technology has always been lagging behind the smaller formats. And any advantage CCD used to have over CMOS is no longer valid; whether a sensor is CCD or CMOS tells you nothing about its quality.

Link | Posted on Jan 22, 2014 at 13:47 UTC
On GalleryItem:2680985 (1 comment in total)

Demonstration from the applet at:
http://webphysics.davidson.edu/applets/optics/intro.html

Posted on Sep 3, 2013 at 20:20 UTC as 1st comment
In reply to:

fibonacci1618: This is frankly almost too good to be true, in that it offers ultra wide angle at one end, and ultra tele at the other end. Really wonder if the lens ends up making too much of a compromise at the wide end, or at the long end.. Will have to wait & see the sample results.

16mp on a 1/2.3" really is pushing it. If the sensor has been further optimized so that the photosites more effectively capture light, & it ends up achieving the same quality results as an existing 12mp sensor, then fine. But I'm already sensing (pun intended) that 12mp is already pushing it in current sensors & ideally it should be 10mp for this small sensor size. Oh well.

I'm hoping that 16mp is an indication that Panny has designed the 1200mm end of the zoom to have high enough resolving power & quality... That would be an amazing feat in itself. And at f/5.9 to boot. Really not bad...

I wouldn't say 16mp is pushing it. With current technology, they've been able to get great results with pixel sizes under 2 microns, and sensor designers seem optimistic that technology will continue to improve.

Link | Posted on Jul 18, 2013 at 13:09 UTC
In reply to:

JJ Rodin: Sadly, I do not even consider a 1/2.3" sensor camera if it has more than 12mp.

Strange that 'need more cam sells' companies do not realize that their 'magic processing' really does not make up for itty-bitty photosites, 12mp is more than enough for these camera types, R U listening ???

Untill a new 'physics' is created, cell sites need 'rooom' to suck in those photons, no magic DSP makes up for physics!!

Not sure why all the complaining about the megapixel count. Cameras with smaller pixel counts DO NOT provide better images. It's been shown again and again.
And do you really think the difference between the pixel sizes pf 12MP and 16MP are that extreme?

Link | Posted on Jul 18, 2013 at 12:55 UTC
In reply to:

Roland Karlsson: So simple, yet so ingenious, The Bayer CFA pattern. No matter how you think, you cannot find a more economic pattern. Many people have tried. There are variants, like the ones Fuji dreams up now and then. But, its only variants, in some way better, bit overall less efficient.

Not many people have made an invention that have had such an impact.

Now, we really want a real three layer RGB sensor. But ... its very hard to make one. The Foveon is a good try. It works. And it has some merits. But, it still dont beat the Bayer CFA in economy. Eventually someone will make a three layer sensor that do beat the Bayer CFA solution. But, it will take several years from now.

My thoughts go to Bruce Bayer´s family and friends. May they find some comfort in that Bruce Bayer was one of the more influential persons on this planet.

I don't see a three-layer sensor outperforming a Bayer sensor. It's less sensitive by design (among other issues). I think the fact that Bayer's design is still the top-performing one 36 years later says a lot about the brilliance in his solution.

Link | Posted on Nov 22, 2012 at 00:50 UTC

Even if the hype were all true, I think the samples show pretty well how pointless this technology except in the case of missed focus, which is the exception, not the rule.

Link | Posted on Aug 19, 2011 at 12:50 UTC as 34th comment | 1 reply
Total: 60, showing: 41 – 60
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