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...
- A better way of doing photography
- Testing the Pen F and the A7S III
- A quick review of the test results?
- A few additional thoughts
- Conclusion
1. A better way of doing digital photography
- 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
- N - The aperture or f-stop
- t - The Shutter speed
- S - ISO setting (image brightness)
- L - Avg. scene luminance (illumination or a flash)
- 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
See this article discussing the 7 points each digital photographer should know...
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?
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.
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.