High-sensitivity sensors for cameras like the OM-3

Last update: 29th August 2025

I have been observing YouTube channels focusing on the OM System OM-3. What sparked a discussion with ChatGPT were those explaining their preference for M43 cameras like the E-M1 III or the EP-7. It also seems like YouTubers feel compelled to justify positive reviews of the OM-3 or the OM-5 II. Does this indicate a trend or an accurate reflection of the M43 segment, or should we rather focus on the overwhelming positive feedback from those opting for smaller camera solutions?

My discussion with ChatGPT highlighted the technical weaknesses in the commercial layer's definition of digital camera efficiency. We reviewed the reasons why the OM-1 II or the OM-3 stacked BSI sensor is most likely a high-sensitivity sensor. It's rare to experience this amazing sensor with cameras like the OM-3, as one expects this level of refinement from pro cameras like the OM-1 II.

I decided to use ChatGPT to analyze the Olympus E-M1 III and the Sony A7 IV in an effort to find a more reliable measure for sensor efficiency than physical size. The E-M1 III has a Live MOS sensor, and the Sony A7 IV has a BSI sensor. The EM-1 III is the most capable pro-level camera from the E-M1 series. What differentiates the E-M1 III from the E-M1 II is the TruePic IX image processor. The latest OM-1/OM-3 TruePic X processor and the stacked 20MP Quad BSI sensor offer significant advantages. This commitment to photography cameras became a rarity during the past 5 years.

My discussion with ChatGPT included the 2-stop sensitivity gain of the new BSI sensor in OM System OM-1 and OM-3 cameras. We reviewed a more reliable measure for sensor sensitivity, which included the ISO-to-SNR benefits of the 2-stop extended M43 in-focus (depth of field) range. Everything changes as we learn there is more to digital cameras than the physical size of the sensor.

Did you know that the OM-1, OM-1 II, and the OM-3 have the same sensor?

Olympus EP-7 enhanced raw file converted and edited in Workspace.

A brief summary of my discussion with ChatGPT.

We started with basic knowledge and how to measure the efficiency of complex electronic parts. This know-how benefits all digital photographers, not only M43 photographers, as a good understanding of these basics will improve your ability to evaluate and select new camera equipment. 

I cropped ChatGPT's replies so that they can be viewed as pictures.

The following ChatGPT reply discusses the above feedback and how it applies to image sensors. For instance, is physical size a reliable measure for sensor efficiency, or do we need more?

The chances of finding a truly equivalent sensor size comparison are almost impossible. Equivalence means all the optical plus technical aspects need to be similar. Focusing only on optical aspects will result in inaccurate comparisons. See this fun example of rating the bigger one better.

The next question reviewed camera and sensor differences. Searching for a better way of expressing sensor efficiency, the aim was to quantify the differences in exposure stops. A more practical way is to say the difference between pro-level (more sensitive) and budget sensors is 2 to 3 stops? 

This could encourage a more meaningful discussion than repeating "bigger is better."

The next conversation examines the E-M1 III and the Sony A7 IV. The aim is not to compare them but to highlight technical differences. AI questioning and probing techniques are crucial when searching for specific and theoretically accurate information. Poor questioning techniques generally lead to pleasing replies from most AI platforms. All information from AI needs to be verified and challenged. Use the AI replies in this article to start your own search for accurate information.

Please let me know if you have any questions.

ChatGPT reply: Part 1:

                        CFA = Color Filter Aray

Part 2:

Part 3:

I included the following replies, as they share relevant information for those wanting to improve their digital know-how. Much of what I cover in my articles is reflected in these AI replies. There is much more to digital photography than what is presented in the commercial information layer. The secret is to focus on those aspects making a real difference for all digital photographers.

This link discusses the commercial versus factual information layers.

The next question discussed the 2-stop M43 depth-of-field advantage. For example, how do we apply this benefit to optimize our ISO-to-SNR ratio? This knowledge is only crucial if you want top results from digital cameras. Typical applications are landscape, low light, or product photography. Study my articles discussing the digital photography flow diagram for digital cameras.

The final question considers the 4th exposure variable in the exposure formula. Yes, it is possible to manage shadow and highlight clipping. The sensor's dynamic range is only another variable.

Folks, there is no need to apologize for the M43 segment or when recognizing that there are almost no visible image quality differences between most cameras. The OM-3's shadow details did benefit from the new BSI sensor. What surely made a difference in application is the TruePic X image processor and BSI sensor combination. That said, I get great results from both my E-M1 III and the OM-3.

If physical sensor size is not a reliable indicator, what criteria should we use to rate digital cameras? As said, budget sensors are 1 to 2 stops less sensitive than professional sensors. The key difference between digital cameras is advanced features and autofocusing options that enable us to repeatedly capture great results in diverse conditions. Some of these differences are not associated with casual or hobby photography but are more relevant to professional photography applications.

Olympus EP-7 enhanced raw file converted and edited in Workspace.

The camera's image processor governs critical image quality markers, such as the gamma curve, white balance calculations, image sharpening, image color priorities, and fine detail processing. This makes it factually incorrect to say that larger sensors capture and produce "more" image quality. It is better to highlight the roles and definitions of the sensor and image processor more accurately.

I appreciate that AI is an ongoing project and not a mature and reliable service. My intention is not to suggest AI has reliable information. Nothing beats an inquisitive mindset, experience, and knowledge. My recommendation is to learn and to question everything you see, read, and hear.

See this interesting image quality test I did with 15 cameras - link.

Best

Siegfried