The new OM-1 Stacked BSI with Quad Pixel AF...

Last updated:- 22nd January 2023

Introduction.

We see the main areas improving when we study the image sensor and how scientists spend R&D dollars. That said, it's good to focus on all these components:-

• Speed (new generation sensors are faster)
• Resolution (the trend is to have more megapixels)
• Sensitivity (Optical & Quantum efficiency - very important)
• Firmware (Sensor and camera CPUs - Image Processors are crucial)
• Sensor Noise Floor (a smaller noise floor with each new generation)

The video discusses the new OM-1 image sensor and why it's a critical development for Micro Four Thirds. We see how Olympus photographers benefited from the OM-1 sensor improvements. We also take a closer look at the new Stacked BSI Image Sensor and why the step to BSI technology.

Camera reviewers never discuss the losses associated with more pixels. For example, any improvements in sensor sensitivity, firmware, or image processing are used to offset the losses from adding more and smaller pixels. OMDS did the opposite and kept the OM-1 resolution the same at 20MP. This pixel count and the new BSI sensor technology made it possible to improve the OM-1 noise performance with up to +2EV and the DR with +1EV. The BSI sensitivity also improved the OM-1's ability to capture detail. These are the benefits of moving from a MOV CMOS to a BSI CMOS sensor.

As seen in the video, it's technically possible to explain why the BSI sensor is better. Looking for similar examples, study the Sony A7 II and A7 III. Like the EM1 and the OM-1, the A7 II / III have the same sensor size and resolution. Like OMDS, Sony also achieved the "standard" BSI noise improvements of +1.5EV and the DR increase of +1EV with the A7 III. 

Olympus EM1 III with 12-200mm lens and Pro Capture function.

In the following example, Sony used the improvements to the new A7 IV image sensor to offset the losses of adding 40% more megapixels. No matter how you view it, pixels come at a price. In other words, except for the additional pixels, the A7 IV image quality stayed similar to the A7 III. This is an example of how much sensors improve from one generation to the next...

It is crucial to challenge those saying stacked BSI sensors have no benefits. Ask for the same detailed information as in this short article and video. It became so easy to randomly drop incorrect statements on social media.

The R&D on the new image sensor started below the surface. Pixels capture Photons, and pixels are the link to Sensor Sensitivity. For example, scientists will target the noise floor of the sensor, and they will focus on Optical and Quantum Efficiency. The stacked configuration improves the operation and speed of both pixels and the image sensor.

Olympus EM1 III with the 12-200mm lens and the Pro Capture function.

Stacked BSI Live MOS sensor with Quad Pixel AF

A big thank you to the forum poster who posted positive feedback on my OM-1 video. Another forum poster asked for information on the "Quad Bayer AF" solution. The information in my video is enough to help photographers understand the Stacked BSI sensor. Obviously, some photographers like to have more, and that is good.

The source is OMDS                   

It is always better to rely on information from manufacturers. For example, see the OM-1 press release further down. You will see OMDS talking about their Cross Quad Pixel AF solution. This is something we can research. Having done that, we see the first Quad Pixel AF solution came from Canon. The Quad Pixel AF is the next level up to the older Canon Dual Pixel AF solution. Dual Pixel AF is similar to the Standard CMOS technology Canon has been using for years.

It could be that OMDS decided to select a new sensor manufacturer to take this new Stacked BSI - Quad Pixel AF sensor with the more powerful Truepic X CPU to the next level. The main benefits of the Cross Quad Pixel AF sensor are speed, accuracy, and a 4D-type AF capability. This improves the Uni-Directional Dual Pixel AF solution from Canon with all its limitations.

3 aspects of the new OM-1 sensor should be discussed more:-

1. Pixels capture Photons, and it is possible to improve image sensors...
2. There is so much more to discover about this amazing new image sensor
3. We are also seeing more excellent images and feedback from OM-1 users

The official OM-1 news release...

Interesting additional reading:-

- Quad Bayer Sensors - what are they and what are they not - link

- Bringing Backside Illumination to high-speed applications - link

- Interesting explanation of the Quad Bayer section and sensors - link

- Also see this info on Wikipedia (Fuji, Bayer, Quad Bayer, and more) - link

- Comparison between front, and back-illuminated sensors - link

- One more site with detail on the sensor - link

- See this discussion on image quality on DPReview - link

- Interesting book if you like to study more - link

- See the Sony A7 III description of the BSI improvements - link

- Here are some OM-1 test images for download from Image Resource - link

- Another article discussing OMDS introducing the Quad Pixel AF solution - link

- Peta Pixel discussing the Quad Pixel AF tech with a typical Canon video - link

- One of the OM-Systems  OM-1 launch videos - one of the better ones - link

- OM-1 Review, a great overview from an existing Olympus photographer - link

- "Size and capture" theory & counter-marketing. Do you trust undisclosed promotions? - link

Is the "Size and Capture" theory too basic?

Last updated:- 29th February 2024

Introduction.

I support traditional science and marketing values. That means accurate and mathematically correct data has priority over commercial preferences. I studied electrical engineering, worked as a project engineer, and held several marketing positions in my working career. My marketing training started at a global manufacturer of industrial automation solutions and electrical equipment, and my interest in consumer behavior developed with product launches, the first digital calculator, the original XT PC, automation solutions, large project sales, and the photography segment.

Please study my ISO Low, ISO100, and ISO64 series. My focus in this discussion is luminance (reflected light). We will review the image signal path from the subject to the sensor because our ability to optimally capture reflected light (image signal) depends on the sensitivity (efficiency) of the image sensor and our ability to manage the digital image-taking process. This article illustrates why many photographers question those promoting the oversimplified "size and capture" theory...

Study this article discussing the 7 points each photographer should know...

What are the main technical differences between sensors? We know sensor sensitivity is the sum of the optical and quantum efficiencies of the image sensor. Pixel area (size) influences these optical and quantum efficiencies. The visible impact that pixel area has on quantum and optical efficiency is a good question? For example, the Canon 6D and Olympus Pen-F are 20MP cameras. The pixel area on the 6D is 248% larger than the Pen F. How much does this benefit the Canon's image quality, and what should one look for? One option is the DxOMark IQ database, and the practical option is shadow details. We also know each image sensor has a native noise floor that influences our IQ. The pixel's effective photon-sensitive area also changes for BSI, Live MOS, and Standard CMOS sensors...

The technical characteristics of image sensors are, therefore, unique. The design specs of each image sensor determine its technical characteristics and NOT its physical size. These characteristics include the saturation level, dynamic range, noise floor, and sensitivity of each sensor.

What is the "size and capture" theory? The best place to learn more about this theory is the well-known "size and capture" authority DPReview. Their camera reviews repeatedly explain the benefits of large sensors capturing more light than crop sensors. The "size and capture" theory predominantly applies to sensors smaller than full-frame sensors. It does not equally apply to FF and MF cameras. These are the benefits you should expect from your new FF (large sensor) camera:

• They capture more light...
• Have better image quality...
• Almost no image noise...
• Much better low-light IQ...
• DR with No highlight clipping...
• Better Auto-focus & video...
• The magical FF look...
• Better background blur...
• More and bigger bokeh...
• The joy of perfect IQ...

Interestingly, "Size and capture" theorists never mention the benefits of saturating the image sensor or having a higher SNR. They only discuss "Shot Noise" and never the sensor's Noise Floor. For example, instead of explaining the benefits of saturating the sensor, they use "ISO Invariance" to discuss the benefits of using a higher SNR. ISO Invariance and sensor size are regarded as magical treats...

This article discusses the 4 essentials that will improve your image quality in 2024...

Do you think the "size and capture" theory is oversimplified..?

Sony improved the Quantum and Optical efficiencies (BSI architecture), lowered the noise floor (fewer pixels), and upped the readout speed.

Here are the points we are reviewing in this article:-

1. A better way of doing photography
2. Testing the Pen F and the A7S III
3. A quick review of the test results?
4. A few additional thoughts
5. Conclusion

1. A better way of doing digital photography

The following hearsay theories/trends are associated with the "Size and capture" fanboys:

• Your ISO function adjusts the sensor's sensitivity
• Never use ETTR at higher ISOs because the DR is less
• You don't need a flash because FF cameras have no noise
• They never use a tripod because new cameras have IBIS
• They need high-resolution cameras because they CROP
• They always argue while using the analog exposure triangle
• They depend 110% on FF sensors, AI, and the perfect AF
• Crop sensor lenses suffer from high levels of diffraction...
• They always hope for something new to have more IQ

Take a moment and study the exposure formula...

Everything starts by mastering the image sensor (Fig 1) and exposure. We control 4 of the variables in the Exposure Formula. They are:

• N - The aperture or f-stop
• t - The Shutter speed
• S - ISO setting (image brightness)
• L - Avg. scene luminance (illumination or a flash)

Digital photographers use these 4 variables to expose (saturate) the image sensor or to create optical effects like background blur or bokeh. This is why experienced photographers have a flash or tripod. Some of the most creative photography is done with artificial lighting like LED panels or a flash.

Reliable information digital photographers can trust. It all starts by walking away from "size and capture" fanboys. For example, focus on the following to master your image sensor:

• Sensor pixel diameter influences sensitivity - fewer pixels are more sensitive
• Higher pixel sensitivity improves the sensor's ability to capture shadow details
• Each image sensor has a unique noise floor (noise floor size and types - Fig 1)
• More megapixels means adding noise to the Noise Floor. (pixel control circuits)
• There are two forms of noise. Shot noise and the sensor's Noise floor (Fig 1)
• When calibrating the sensor, the sensor's sensitivity is fixed/set at the factory
• High-sensitivity sensors mean less high ISO noise (low calibration multiplier)
• High-sensitivity sensors typically have a higher saturation point plus DR
• The old analog exposure triangle is not the best choice for digital cameras

Those saying we don't need knowledge or a flash, see this video on flash photography - link.

Olympus E-P7, w the FL300 flash, w 17mm f1.8 lens - ISO200, f4.0, 1/50th.

A quick way of improving your family photos is to consider the subject, illumination (flash), and the luminance reaching the sensor. The secret is more luminance on the sensor and a flash to illuminate and freeze the subject. In fact, keep an Olympus FL-300R flash or the standard OMD flash in your bag. Try the following camera settings for your next family event. Use Manual Exposure Mode with a shutter speed of 1/125th and an aperture of F4.0. Use ISO500 and set the exposure compensation for your flash between 0 and -0.7EV. Your flash is an exposure variable to illuminate the subject. You don't need the best flash/tripod. A bean bag with the clip-on flash or FL300R is enough.

The focus on Reflected Light is a different way of planning and doing digital photography? This is how photographers used to capture photos before the days of AI and Photoshop. Thinking about it, the only new thing is digital photography and learning how to optimize your image sensor.

See this article discussing the 7 points each digital photographer should know...

Figure 1. This is the most critical illustration photographers should study to master image sensors.

2. Why test extremes like the Sony A7 III and Olympus Pen F?

Because the difference between these 2 sensors is BIG? What happens when we underexpose the shadows while correctly exposing the mid-tones to highlights? Will "size and capture" fanboys claim it's all about DR, sensor size, and smaller sensors capturing less light, or are there technical reasons why scientists investing their time and energy to design more sensitive sensors? Are image sensors as basic as "size," or is there a technical explanation for sensor performance?

My challenge was to underexpose part of the subject and manage the performance of the Image Sensor.

I had the opportunity to test my own advice. My son was so kind as to lend me his A7S III for one day. What simple test could I do to push these two image sensors in one day? I decided to use my Pen F with the A7S III. I wanted to see if the SNR of each sensor changes when part of the subject is in the shadows. Will this prove that all image sensors have a noise floor and the SNR is lower in the shadows? The next step was to create a semi-controlled space to record these images.

A quick reminder:- Your ISO setting does not create noise. The ISO setting amplifies the image signal and the existing noise floor of the image sensor. The sensitivity of your image sensor and the SNR at each exposure will determine how much visible noise you see in your final image.

That said, I wanted to test if my thinking process is correct, or should I repent and forever accept the "Size and Capture" theory and focus on that ONE variable, SIZE..?

3. Can we explain these results?

I have no doubt that the Sony A7S III is a fantastic camera. My son uses the Sony A7S III, his Sony A1, and RED video cameras professionally. His customers are happy with his work. My own experience with the A7S III is only positive. The Sony A7S III is a unique camera aimed at videographers.

The same is true for the Olympus Pen F. Against all odds, it has a loyal following, and many new creative enthusiasts are discovering this unique camera in 2023/24. Does it mean we should compete with the newest and most popular cameras? I really do not see any value in that..?

The reason for this test is NOT which is better, or my M43 sensor is super awesome. Each image was taken in a semi-controlled space. I upped the brightness so you can study the shadows. Olympus said the differences between M43 and FF cameras are tiny. Will we see that in this test? 

The change in shadow detail between 0EV and +1EV demonstrates the changing sensor performance (saturation) between the two exposures. This level of control is only possible if you know your digital camera and how the performance of the camera/sensor works. (It is not only ETTR.)

This exercise was exciting. The SNR response is different for each camera, and the saturated and unsaturated parts of the sensor determine the final image look. "Size and capture" fanboys cannot explain these performance differences between the shadows and well-exposed areas. 

Normally (0EV) Exposed Images

The +1EV (Exposure) Images

4. A few more thoughts on the above test images

The two images below are the fully edited raw versions of the above +1EV images. The Sony A7S III has more shadow details, and it took more effort to recover the Pen F shadow details. The reason for this is the sensitivity differences between the A7S III BSI sensor and the Live MOS sensor of the Pen F. Another reason is my Pen F recorded less tonal data in the shadows (See the histogram). I purposely left these final images slightly "flat" so you can study the "recovered" shadow details. 

Here are a few final thoughts about these images:-

• Sensor technologies - LiveMOS versus BSI (Both CMOS but different architectures)
• Technical differences - 2016 to 2020 (Much development happened in these 4 years)
• Sensor Sensitivity - Sensor evolution focuses on Quantum and Optical Efficiencies...
• Sensor sensitivity - Sony selected a super high-sensitivity BSI sensor for the A7S III.
• Pixel Size - It makes a difference + the delta pixel area is the highest for this example
• Sensor Noise Floor - The A7S III sensor benefits from having a smaller noise floor
• Sensor Noise Floor - The BSI sensor + four years of R&D improved the noise & eff.

See the video I did for the OM-1 - link.

I asked the following question in a previous article. Does the sensor backplate record photons? We see the size of the backplate stayed the same while the pixel count increased with each new camera. Doesn't that mean the "size and capture" theory is hopelessly oversimplified? 

Have you ever wondered if pixel diameter is one of many variables impacting IQ?

Then what are the other variables, and shouldn't we consider them?

The image below is best viewed on an iMac or large PC screen.

Don't you think the 17mm f1.8 three-dimensional "M43 look" from my Pen F is awesome? 😉

Conclusion

Why do I think "size and capture" promoters are not serious? Simply study their articles, reviews, and comments. For example, why use Pixel Pitch when referring to the Pixel Area. Pixel pitch is generally used with LED monitors. Why call BSI sensors "stacked CMOS sensors?" Why let people think Standard CMOS sensors have a stacked or layered design? Why not call it a Stacked BSI..? 

Why argue and focus on the placement of components like A/D converters or ISO "sensitivity" when photographers benefit more from learning the correct function of these components? Why do fanboys and promoters always focus on unnecessary or fake theories like oversimplification..?

Best Regards

Siegfried

ISO Low, L100, L64, and Flash Photography - Part 1

Last update:- 16th January 2023

While working on Part 2 of this article on ISO and Image Quality, I thought it was a good idea to set the stage with a few random thoughts and a basic challenge. Thinking about it, every photographer should develop the ability to analyze digital images. A good understanding of the digital camera and the ability to apply this knowledge benefits all digital photographers...

Taken at a constant luminance perspective and a variable image signal amplification

Taken at a constant image signal amplification (ISO3200)

You are welcome to try the following challenge. Place an A4-sized white paper against the wall and your camera on a tripod. The challenge is to recreate the above 2 illustrations. The info needed to create a basic plan, take the images, and build the final illustrations, is all in this article.

Olympus Pen F with 25mm f1.4 Leica, ISO80(Low), f3.5, 1/1600 - Edited in DxO PL-4 (See more info further down...)

Here are a few general questions for you:-

• Prep a short explanation of what happens inside the camera for each illustration
• Think of a few examples and list the benefits of knowing your digital camera...
• Why do you think it's safe, or not safe to use the ISO Low, L100, or L64 options?
• Most social media experts tell us it's not OK to use ISO Low, L100, or L64, why?
• Which of the 5 images in each of the above illustrations are 18% gray samples?
• What is the link between the Zone system, 18% gray exposure, and the ISO setting?
• Study the photons/electrons graph below. Does it apply to all or only some sensors?

For more on how to plan your own strategy, study these articles:

• Start from basics and learn how to record more image data - link
• A better way to control the camera is the 2 Step Exposure Technique
• Why is sensor sensitivity so important? - article (Important info)

A few general thoughts...

The reason photographers should distrust any sensor size references is it's normal for digital cameras to have image noise. What determines this image noise? Most photographers are never told that all sensors come with a native noise floor. Should we trust those reviewers who promote sensor size or write biased camera reviews? This is likely the main reason we don't see discussions about advanced digital photography techniques, like how to use ISO amplification correctly, or how to manage the performance of the Image Sensor. (See this link)

For example, why was the old-school Exposure Triangle never improved? Especially while it's used to train photographers on digital photography? How will they ever master advanced digital camera skills like SNR, sensor saturation, or image signal amplification with an outdated triangle? 

Is size a reasonable measure for IQ? We know pixel area (size) is one of many variables to impact the Optical Efficiency of the image sensor. So why focus on only one of many variables? Well, looking for answers is like finding a needle in a haystack. A more reliable way of rating image sensors seems to be Sensor Sensitivity (Optical and Quantum Efficiency).

To illustrate the oversimplicity of the "size and capture" theory, study the illustration below. This illustration offers more information about the image sensor, the noise elements in the sensor noise floor, and the effective dynamic range of the sensor. Other than the "size and capture" theory, which cannot explain shadow noise, those who master the principles illustrated below will have a strong theoretical foundation. They will improve their analyzing and sensor performance skills.

For example, take a moment and consider the graph below. The horizontal axis is the reflected light or photons hitting the sensor. The vertical axis represents the converted electrons. The sensor's full saturation capacity is reached with a fully exposed sensor. Plot the saturation for shadows or low-light scenes. How does this impact the performance of the image sensor? What happens to the SNR in the shadows? What does the histogram look like for an under-exposed sensor? These are simple questions every digital photographer should be able to answer...

Does the size of the sensor backplate "capture" photons? The answer is NO! We know pixels capture photons and pixels (photocells) convert photons into electrons. This is the main reason why scientists improve pixel (photocell) sensitivity and why they don't design bigger sensors. That said, the size of the sensor does play a role. Any idea what? Think of image effects like background blur.

 

Olympus photographers are familiar with 12MP or 20MP (MFT) sensors. The pixel diameter of 12MP sensors is almost double that of 20MP sensors. We know the EM1 III has one of the most sensitive M43 sensors and delivers far superior IQ to any of the older 12MP MFT sensors. Ever wondered why? Could one of the reasons be, that sensors with lower Temporal Noise have cleaner images? 

Study DxO Mark results for the EM1 II sensor.

The more we learn, the more we see what happens with image quality...

Another illustration with info on how to manage the sensor at ISO3200.

Let's talk about the physical size of mirrorless cameras? The size of the image sensor influences the physical size of the camera? The reason is the lens image circle needs to cover the full sensor. This impacts the size of the lenses, the camera energy needs, heat management, and the effectiveness of features like IBIS. Digital cameras are basically built around the image sensor. The penalty for cutting corners is overheating, lower efficiencies, and less reliable cameras and lenses. 

Separately from any fixed mechanical design criteria, scientists focus on materials and the electrical design aspects of creating more sensitive image sensors. This represents a better way of designing new cameras and improving Sensor Sensitivity. For example, typical improvements in image sensors include replacing older wired functions with modern software or AI solutions... 

As you know, Olympus and Panasonic were the first to introduce mirrorless cameras. Did they also establish the mechanical design benchmark for mirrorless cameras? For example, what is the built-in safety margin on M43 cameras? When you see similarly sized APC or FF cameras, does it mean the M43 camera is over-designed, or are these APC and FF cameras under-designed?

How much image noise is added to the noise floor for each 1-degree increase in temperature..?

Try this quick experiment and point a light source to your PC. Which of these sensors is receiving more light?

If someone says one sensor captures more light than the other, then I cannot help to think, is this statement theoretically correct? I was searching for information when I saw this review. I could not help asking, is this just another Undisclosed Promotion? What if the "more light" benefit was only 0.0002% while those bigger sensors were 10% less efficient? One would like to think, it's all about the efficiency of the sensor when converting photons into electrons, right?

See this discussion. It's a great example of why photographers should push manufacturers for better information. Also, do a quick search on the implications of "Undisclosed Promotions"...

Final comments on the two images in this article

Take a look at the 1st image in this article. I have set the exposure for the bright areas (sky). I wanted the sky with darker shadows. At home, I did a quick test to study the visible shadow noise when I increased the shadow brightness. Editing the raw file in PhotoLab 4, it was possible to extract cleaner image details from those same shadows. Does that mean the image had enough available information in the shadows or is it only PhotoLab doing a great job?

The above example shows the jpeg on the left and the edited raw version on the right. The image was exposed for the shadows, which over-saturated the sensor in the bright areas. It did not clip the highlights while pushing them hard. I tried different editing techniques to get the most from this "data-rich" raw file. The most pleasing result was editing the raw file with Aurora into an HDR image. Did I push the image sensor too hard, or is it OK when we push the image sensor?

The selected images demonstrate the different technical aspects discussed in this article plus it shows it's safe to work with ISO Low on your Olympus Pen F. The same is true for ALL cameras. Don't we benefit more from working with a fully saturated sensor and resetting our final image "brightness" in Workspace? Why is there a link between the camera (Live View) and Workspace? Why sensor size and then push restrictions like don't use the extended ISOs on your M43 camera..?

More about Managing your Image Sensor and ISO Amplification in Part 2...

Finally, what's better, exposing creatively, or saturating the sensor?