#1262. Are camera sensors getting better?

By pascaljappy | Opinion

Jan 14

It depends on your functional highlights, I guess.

Tiny CMOS pixels in an ancient phone (Samsung Galaxy S9), at night.
 

On the one hand, it would be arrogant – not to mention, wrong – to claim that Sony’s (or Tower Jazz or …) reseach and production lines have been stagnant for the past decade.

On the other, it’s equally hard to deny that many artists – photographers not bound to productivity but to quality – still prefer film, and that many amateurs still get a warm fuzzy at the idea of CCD.

Let’s try to analyse why.

Red sky in the morning, highlight warning
 

CCD vs CMOS (vs film)

The superiority of CMOS over CCD is a common misconception. A CMOS sensor is a digital chip which converts the charge produced by electrons (created by photons falling on the light sensitive surface of the chip) into voltage, on the spot, via electronics present in every pixel. This is then shipped to an number of on-chip analog-to-digital converters, via circuits also present in each pixel.

A CCD sensor is an analog chip in which a pixel merely collects photos and converts them into charges. Those get pulled out, off-chip to an external A/D converter, then processed as an image in the same way as what comes off a CMOS sensor. A much larger proportion of every pixel is devoted to light collecting in a CCD, and no electronic noise from the other activities contaminates the images. Besides, off chip converters can be of higher quality. While much of that head start has been compensated by over a decade of R&D, CMOS (in its various BSI and stacked variations) still hasn’t quite caught up to CCD in terms of quality.

However, having processing on each pixel and a greater number of converters and amplifiers on-chip makes CMOS sensors a lot faster, a lot more frugal (CCD chips can use as much as 100x more energy as CMOS sensors do) and they are also a lot cheaper. So, pratical aspects (eg video), not quality, are the reason why CMOS has kicked CCD out of the arena. It’s understandable in an efficient market, but it still feels like a great shame that no outlier company is offering the choice of CCD to the nostalgic among us.

Pixelated hawk
 

Film is another topic altogether. Being a chemical process, it comes with a limited set of advantages and a boatload of hinderances: cost, pollution, limited availability, technical limitations … It’s appeal is undeniable for many reasons, though.

For one thing, it sill looks immensely better in the highlights than anything digital can offer. And, film’s tone curve, to objective eyes, make it more natural and lifelike, in spite of all the other technical shortcomings. Then, there’s the fact that it comes in a very limited number of options. The digital market wants us to believe that more is better, but more is in fact harder, a lot harder. When you hone your technique on 3 filmstocks, you eventually get in tune with them and very proficient. Good luck with 200 presets or the absolute blank slate that is a RAW file in Lightroom. Finally, for some reason, chemical grain looks nicer to the eye-brain than digital noise. It feels like an aesthetic choice rather than a defect.

Of course, analog purists will tell you that the process is also a major part of the joy of film. No chimping, the surprise of results and other romantic concepts. And while I never chimp and do whatever I can to maintain flow during a session, the idea of feedback soon after that session appeals to me a lot more than heading to the post office to offload my films. But to each their own. If your life is constantly dictated by the rhythms of a phone, cooleagues who never unplug, social media, instant gratification and digital overdose, the process of slowing down to the beat of a faraway chemical lab must indeed be quite soothing.

Barcode sky
 

Old sensors vs new sensors

But what about progress in CMOS sensors? Is a camera from 10 years ago as good as a camera from 10 days ago? Generally speaking, no. The first CMOS sensors were noisy, and not in a good way. And the technology has made big strides, until recently. Until resolution got in the way.

Photosites (the light sensitive area in pixels) convert photons to electricity with a certain quantum efficiency. CCDs are about 30% efficient in green light. Recent BSI CMOS sensors hike that up to 80%. This means that 80% of photons hitting the sensor get converted into electric charge, instead of 1 in 3 (or 1 in 4) with CCDs. It also means that the best improvement we can realistically hope for – ever – is a few unnoticeable percent, as no cheap sensor will likely breach the 90% anytime soon. And it’s been that way for a number of years. In spite of this, we have seen ISO ratings go throught the roof (using sensors that aren’t more sensitive to light than the previous generations).

Enter noise. Several sources of noise can degrade the quality of the signal. Dark noise, which happens as the exposure goes on, amplification noise, readout noise, conversion noise … If you have 20 000 electrons in your pixel and your cumulated noise is 8 electrons, your signal to noise ratio is 20 000 / 8, or 1250 to one, or just over 10 bits (2^10 = 1024). If you have 8 electrons in your pixel and a noise of 8, your S/N ratio becomes … ghastly. So, to improve on this, you can expose longer to capture more electons (which was the rationale behind Expose To The Right, a good idea in the bad old days, not so much today) or you can lower noise (by using a CCD, or by cooling the chip or by other means, including better on-chip circuits).

The white hole
 

The best image quality comes from the chip that produces the highest signal to noise ratio. External cicruits that handle that signal also matter a lot (paying big money for such very high quality circuits is part of what got Pixii their record DxO rating, for example, as well as their post-Covid supply chain agony). But let’s just focus on sensors for now.

All things being equal, a larger pixel can collect more photons than a smaller one. Double the lateral size of a pixel and you quadruple its surface. That’s why cameras such as the Nikon D700 still have their followers today. Look at that sunset from the same article. Good luck taming those highlights with a high res sensor today.

Higher resolution essentially slices the sensor in smaller pixels. While the noise of each pixel remains the same, the amout of electrons each can hold gets sliced as well, as does the S/N ratio. Add to this the pixels added to control AF and other possible stuff I may not even be aware of, which all contribute to the diminution of captured photos, and you see a trend towards lower image quality and higher functionality. And yet, sensors keep getting measurably better. How?

Soothing Mandler love
 

For one thing, sensor technology is improving. While smaller photosites hitting a quantum efficiency glass ceiling can never capture more photons, noise can and does get improved over generations, keeping the S/N ratio ballpark, or attempting to. Then there’s the optimisation of circuits (Sony is legendary for its packaging and Pixii uses higher grade components than the rest of the industry, to name just two). Then, there’s image processing.

Sony’s astrophoto community fallout, a few years ago, was due to the company’s in-camera “cooking” of the noise books in order to simulate higher ISO than the electronics could actually muster. And there’s nothing wrong with that. Computational photography is the way ahead for our hobby. Phones are getting brilliant at it, and some camera brands are waking up to it.

But there’s something else at play: the market. You, me, selfie addicts, influencers, journalists, social platforms … Sony’s main persona is the content creator, not the photographer. As Susan Sontag brilliantly described decades ago, capitalism cannot thrive without intense flows of imagery. This skews the manufacturers not just towards functionality (AF, IBIS, frame rates) but towards almighty versatility (ISO, resolution) and measured performance, over pure aesthetics.

See if I care
 

But it’s written neither in The Bible, nor in the canon of quantum mechanics that a sensor can’t be designed with photographers in mind. And it’s written in every eye doctor book and in cine history that it would be a great idea to do so.

When’s the last time you were in complete blackness, with areas of your surroundings you could make out no detail from? Quite frequently, if you ever walk at night. It feels entirely natural, though potentially scary. But when’s the last time you saw clipping? Take you time. Not ever, is the answer.

It’s no accident that 9-figure budget movies will gladly use $200 30 year-old photo-lenses to shoot important scenes (aberrations do not harm suspension of disbelief) but will go to any – repeat any – length to avoid clipping (which can instantly bumps the viewer out of the story). Lighting is a huge budget in those productions. And it’s no accident either that the leader in cine cameras, Arri, uses a sensor with a highlight bias, and that RED’s legendary RAW compression treats highlights with the utmost prudence and respect.

Highlights rule
 

Compare that to the white chalk treatment of even expensive digital cameras, and you wonder why photo camera manufacturers don’t bother. Film does it well (and is enjoying a comeback), CCDs did it well (longing sigh), Phones are doing it (somewhat) better, and recent rumour suggests Hassy may be improving in the X2D (yaaaaay). Pixii, again, favoured highlights in its Monochrome mode tone curve, which probably measures worse for it, but looks beyond gorgeous. It isn’t a matter of fashion, or trend, but of human vision …

My analog-photo man-crush Jason, from the Grainydays channel, has embarked on a daily chugging of some ungodly type of Mountain Dew drink to pester Kodak into bringing back Aerochrome, a special filmstock he much loves. This post is my plea to the digital photo industry to produce more sensors and more cameras for … you know … photographers?

Enough with the resolution madness, enough with the ISO craze, enough with the framerates and quantifiable everything. Yes, sensors have gotten better. Now, could we please, please, please, in 2023, 50+ years after film nailed it, get proper highlight management in digital cameras???

 

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  • Gerard Hearne says:

    I used to photograph weddings … on film, colour film (Kodak or Fuji 120 & 220 on Hasselblads). Although it was normal then to shoot blind with no visible certainty as to what you were getting, you had to know in your head, the thought of doing that now seems quite frightening. That is I think one big advantage of digital, you know that you are getting SOMETHING as you go along. In the early days I would post the films and get negatives and prints back nearly a week later. As time went on I processed my own films immediately after photographing a wedding (in a Fletcher C-41 handline) for peace of mind, the theory being that if there was a problem you could dash back and take more photos. Fortunately I never had to do that.

    • pascaljappy says:

      Hi Gerard, I can’t begin to imagine the stress that must have flooded you and other professionals when a roll of film looked damaged or when you suspected an error such as the wrong ASA setting. That’s the main difference between professionals and amateurs. You *have* to get the shot, we are only disappointed when we don’t. Digital must have been a huge relief. But I also read multiple testimonials from pros shooting digital describing the burn out that comes with sorting and processing those hundreds, or thousands of images, at every shoot. Imagen will probably do the same to those pro’s peace of mind as that Fletcher C-41 handline did for yours 🙂

      I’m certainly not dissing digital. Having considered a move back to film multiple times, the realities of living with film always kept me in the digital camp. I just wish we could get that one thing film still does so much better, highlights 😉 Cheers.

  • jean pierre guaron says:

    What a wonderful idea. Get the industry to listen to its customers, and what THEY want! Are you some kind of radical bolshevist?

    Best response I’ve seen from the industry is to encourage photographers to do what you’re suggesting by delving into exposure bracketing – taking three shots instead of just one – and amalgamating them in a special post processing HDR software.

    I’m envious of your solution – getting a Hassy! – famously, they produce far better highlights (and lowlights, too, for that matter). Unfortunately I wouldn’t have the same range of lenses, based on bulk – weight – cost – and availability. So I would be unhappy for other reasons.s

    • pascaljappy says:

      Just a dreamer, remembering the days when pleasing the customer was good strategy and the C-suite wasn’t populated by people who think they know better.

      HDR often looks unnatural, sadly. None of this is rocket science. If RED can produce perfect results from an APS-C sensor, surely Canisony can as well …

      • Ian Varkevisser says:

        Hi Pascal,

        Even the humble little Fuji prosumer cameras have an HDR mode which shoots 3 images , 2 ( or more ) stops apart, and combines them into an in camera RAW HDR image – of the same quality and as natural looking as a normal RAW image. And it will convert it to jpeg based on your favourite recipe.

        Sure its not as high dynamic range as 5 images , 2 stops apart combined in external software – but with the already passable dynamic range of the sensor it is a big time saver and produces quality images for pretty much most conditions right in camera.

      • jean pierre guaron says:

        I’ve never tried HDR – done hundreds of “focus stacking macro shots, and they all work fine. I’m happy to take your word for it, with HDR

  • Pascal Ravach says:

    Bam! Straight to the point 🙂
    And *the* main reason I could not push myself to buy a new camera for so many years now, sticking to my old E-M1 and A7R2…
    After waiting more than 30 years (!), I finally accepted that I was dreaming when I expected Olympus (or someone else later) to release a « totally manual » small size FF body for my beloved legacy lenses and wonderful complete macro sets, with large pixels, zero gimmick and a decent S-curve… so I often pull my old bodies (OM-4 Titanium) from the storage and hesitate to come back to film…
    And yes too, I am surrounded by « new generation » lovable, nice people… who shoot 10 version of their latte with their phones :)… the « soothing » you mention sometimes looks more like mental survival!
    We keep pretending we can just use digital the same way… dunno, but it simply never worked for me… film just « imposes » that « slow mode »… in 1995, I took 15 rolls with me to a 3 months travel in China and Tibet… 450 slides; came back to home, got… 3 blurred and all the rest quite nice, with a lot of keepers!
    Today I would come back with minimum 4000 photos from the same trip, and what? 50 keepers? I don’t have your talent, and something else might be at play, but for me the whole digital adventure has been more of a gradual « disconnecting » one…
    In the 80’s I shot exclusively Fujichrome 50 to 100, mostly Velvia; checked 10 years ago, the slides were impeccable, and once scanned with my Nikon V ED, the results are so « real »… sight 🙁
    If ever *one* manufacturer could hear your rant and « see the light » (pun intended :D)…

  • Adam Bonn says:

    I really enjoyed this one Pascal,

    The maths stuff about light was very insightful, (you need to stop pretending you don’t understand when I bang on about the colour management of the adobe dcp pipeline)

    Dare we say that CCD is the betamax to CMOS’s VHS or the CD to the (original format lossy) mp3?

    As a proud owner of a CCD camera (it’s an M9) and also a CMOS camera (it’s an M10-R) I get to compare the same shots with the same lenses and the same sensor size (obviously one is 18mpx and the other is 40 though)

    Sometimes I wonder if the CCD look is all in my mind… a perpetual pleasant hangover of the excitement of that first Leica and all the memorable shots I made with it of pre-completely-gentrified Porto and my kid growing up, ie is the magic simply that those shots can’t be captured any longer (kid is preteen and ruined buildings are now air BnBs)

    Certainly ‘everyone’ can agree that CCD is magic, but no one can really define it… (M9 is variously labelled as filmic or kodachrome-a-like )

    For my two drops of opinion thrown into the seething cauldron of emotive description, you’re right about the highlights… BUT, the M9 (which I appreciate isn’t the only CCD camera in the world it’s just the one I’ve been shooting with for 5 years whilst various newer CMOS cameras have come and gone) is a low DR camera, when it clips highlights it really does….

    ….but it has a relationship between dark-mid-light tones that I don’t see in CMOS cameras… (I suspect the word is tonality), in a thumbnail view the M9 image looks sharp and at 100% view it’s often not, meanwhile the CMOS cameras look muddy as a thumbnail but are actually tack sharp at 100%

    This seems to give a depth to the pictures that CMOS doesn’t easily replicate… I suspect the same MIGHT be true of film too… I haven’t shot film in 20 years (and back then my preference was TMAX 3200, low light and grainy) so I’m not well qualified there

    Of the post M9 Leicas I think the M10-R (I’ve never had the M11) comes closest to the CCD look of the M9… the latitude is comparative and all those tiny pixels give a slightly similar graininess to the pictures.

    I was never going to type this much and not mention adobe!! It’s worth noting that adobe has very much changed how their image pipeline works in the past 8 years or so (super briefly, same components using different ways of delivering gamut compression), which makes comparison harder… I suspect there’s some truth to that with film too… the film part’s the same but back in the day folks weren’t getting 4k neg scans and presenting them digitally.

    Anyway far too long of a comment!!!

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