Last update:- 23rd July 2024
Introduction.
Several social media presenters started 2024 listing new photography essentials. While having good intentions, it's always sad to see popular influencers making information mistakes.
This inspired me to discuss a new ISO technique plus the following Essentials:
- "Focus" on the subject, and don't let the background or DR distract you.
- Exposure Triangle - Replace "ISO Sensitivity" with "Image Brightness."
- Ignore all "size and capture" theorists explaining image sensors/cameras.
- Knowledge and experience are critical aspects of digital photography.
Imagine you are photographing blue hour or nighttime scenes, and it was possible to lower your image brightness just enough to reveal more detail in highlight areas like street lights, lamps, shop windows, and restaurants without affecting your image quality. How did I capture the images below? I used a new technique that controls the sensor separately from the ISO. That means I independently manage my sensor's performance (saturation level) from the ISO (image brightness).
1. Focus on the subject, and don't let the background distract you
2. Remove ISO Sensitivity from the Exposure Triangle
The best way to think of the ISO function is to view it as an in-camera brightness slider. The image sensor and ISO amplifier are separate components. The sensor's sensitivity is measured and set at the factory. This is a once-off and permanent adjustment that prepares the image sensor for use with digital cameras. The ISO function simply amplifies the image signal from the sensor or pixel...
See this article for more information.
Why should the "Digital Exposure Triangle" be different? Because it should reflect what's happening inside the camera. This knowledge helps us to manage the sensor's performance separately from the ISO (image brightness). The full-frame "size and capture" theory plus "ISO sensitivity" limits us from focussing on the sensor's performance. For example, the "size and capture" theory and a lower DR at higher ISOs are incorrectly used to discourage photographers from using ETTR.
This article reviews the benefits of knowing it's possible to separately manage the sensor's saturation from the ISO. This knowledge makes a huge difference in how we apply our digital cameras...
The information below applies to all digital cameras:
- The Shutter and Aperture are responsible for exposing the sensor.
- The ISO function only amplifies the image signal from the sensor.
- Keep in mind the ISO is part of the camera's exposure calculation.
An example of incorrect information...
Consider this when you use the Digital Exposure Triangle:
- Reflected light (Shutter Speed and Aperture) controls the sensor's saturation level.
- More reflected light saturates the sensor. This improves the SNR, which decreases noise.
- Less reflected light decreases Saturation/SNR. A smaller SNR means more visible noise.
- Study the Photons to Electrons conversion graph in one of my previous articles - link.
3. Avoid any "size and capture" theorists explaining digital cameras
Please study the 2 images in Figure 1. The image on the left is a JPEG from my EM5 II, and the one on the right is a converted raw file. These images are an expression of understanding the digital camera and Workspace. They were not created with AI, computational photography, a LUT, or advanced image editing. Photographers in Group A will typically say the EM5 II's dynamic range is too small, and those in Group B will seek new information to improve their knowledge and technique?
What did we learn from "size and capture" promoters? They sell the "fact" that digital photography is better with bigger sensors. Some of the deliverables are dynamic range, background blur, image quality, image noise, and details. These "size and capture" theorists never differentiate between the photographer's experience or the camera's optical and technical characteristics...
4. Knowledge and experience are critical aspects of digital photography
What information is necessary to discuss the photos in Figure 1? Image quality is proportional to the sensor's saturation and image brightness is adjusted with the ISO, Gamma Curve, and Exposure Compensation in the Camera and WS. The EM5 II is known for its good IQ and the sensor's small noise floor. The DxOMark Low-Light ISO rating defines acceptable and good image quality.
- This technique benefits from the Enhanced Raw Format and Workspace.
- The Enhanced Raw Format is the link between the ISO and Workspace.
- Evaluate the quality of the reflected light and set the ISO to 400 or 800.
- Use the histogram to expose the sensor (Aperture & shutter speed).
- The histogram follows the sensor's saturation level with a fixed ISO.
- Lower the ISO" in 1/3EV intervals to manage" any clipping highlights.
- Finalize your image brightness in WS (EC) and export a 16-bit Tiff file.
- The final step is to tweak the exported 16-bit Tiff file in Photoshop.
Is there another way of creating Photo B? Yes, I used the above method to illustrate the relationship between the camera's sensor and ISO function. Some will say the EM5 II is ISO Invariant. Folks, the "size and capture" and "ISO Invariance" theories are marketing programs. Those pushing them cannot explain why we have image noise, a noise floor, and why all sensors are not "ISO Invariant."
It's possible to manage the sensor's performance when we know that clipping highlights are not always linked to a smaller dynamic range. For example, the sensor might be perfectly exposed (saturated), while the ISO setting (image brightness) is responsible for clipping the highlights...
The following steps explain how I created Image B:
- I used Image A to create a ref auto exposure of ISO200, f4.0, 1/25 for the EM5 II.
- The DxOMark "Low Light" Sports rating showed I could vary the ISO with 2-stops.
- That means I could adjust the "highlights" when I start with ISO800, f4, and 1/100.
- I used ISO200, f4, and 1/80th in M-Mode. (No clipping & sensor @ 20% ETTR).
- I corrected the image brightness (Image B) in WS with Exposure Comp & Tonal adj.
It takes time to visualize and create new techniques. It improves our ability to problem-solve Olympus Cameras and Workspace. For example, the concept that ALL sensors have a noise floor underlines this new ISO technique. It's possible to control clipping highlights with an optimally exposed sensor. The Enhanced Raw Format enables us to finalize our ISO value in the camera and/or WS.
Here is another method to create Photo B (Fig. 1). Olympus cameras automatically vary the sensor's saturation level with AE Bracketing. That means the camera doesn't change the ISO in AE bracketing mode. Use ISO800 and the "2f 1.0EV" bracketing option to take 2 photos. Manually take another image at ISO200 (-2EV) and the 20% ETTR aperture and shutter values. Do the final image brightness and Gamma Curve adjustments in Workspace and export the image in a 16-bit Tiff format.
Conclusion
Most digital cameras from 2012 onwards have acceptable to good IQ. Modern marketing and collective dynamics continue to push for more image quality. Be aware of the dumbing-down effect of everyday marketing and reject any "bigger is better" theories. Study and master your digital camera.
4 comments:
INtwresting article but I think I'm only part way to understanding.
Could you explain more around " I could safely vary the ISO with +/- 2EV.
That meant the camera's "highlight" exposure settings should be f4 and 1/100 at ISO800."
Iam assuming this is to create an image that captures the highlights for an HDR image?
For +2EV from f4 and 1/25s shouldnt it be a 4 times longer shutter speed with ISO setting remaining at 200?
Thanks
The DxOMark low-light rating says we can safely use ISO800. That is 2EV image brightness. That means my shutter speed will be 1/100 when I up my ISO to 800. This is not a HDR technique...
The ISO setting is part of the exposure formula. It's also important to remember that the camera's aperture and shutter expose the sensor and the ISO only adjusts image brightness.
That makes the question simple. Did the highlights clip because I over-exposed the sensor or increased the image brightness too much?
I updated the article. pls study it again and let me know if it reads better :-)
Thank you for your question.
Siegfried
Very interesting article. I have only recently come across your site, and find it very informative. Despite all the full frame gainsayers I invested heavily in Olympus equipment some years ago, and for the photography I do I have found it to work really well for me. No plans to upgrade to FF.
A question on this article, please. I have always used ISO 200 when I can on my Olympus cameras, as this is the level Olympus recommend for optimum results. Of course I do use other settings when circumstances require it, with generally good results if I don’t push it too far. You seem to be suggesting that a base of 800 ISO should be used, shutter speed and aperture selected to give a correct ETTR exposure, and any highlights clipping controlled by reducing the ISO value. I appreciate that reducing ISO to avoid clipping will reduce the actual ISO value somewhat, but it will probably still be higher than the recommended 200. I imagine that you have found the advantages of your new approach compensate for moving away from the recommended ISO? I will give it a go and see how I get on.
I would also like to check that I have understood correctly what you mean by a saturated sensor. I have known about the benefits of ETTR for a long time, and try to use this in practice as much as I can, without clipping important highlights (not always easy to identify in the field sometimes). I ran some tests on my Olympus cameras, and found that the red highlight warnings are pretty accurate compared to what I am seeing in Lightroom - there is perhaps1/3 stop difference. This knowledge is very useful. I have assumed that when you refer to a saturated sensor, you mean a that the sensor has received the maximum exposure possible for the subject, without clipping highlights. Am,I right, please?
Thanks very much for doing the research and publishing these interesting articles for us Olympus fans.
Hello Brian
Thank you for your kind feedback. The key to understanding my ISO800 comments is to study the exposure formula and how cameras function. Also, see my Dramatic Clouds and Exposure Techniques article.
What happens is that the shutter & aperture expose the sensor, and the ISO is simply a brightness amplifier. That means the sensor might be perfectly exposed while the ISO setting is responsible for the clipping. They are all part of the exposure formula...
That does not mean I suggest to use ISO800. I want people to understand the role of each setting. For example, how does one see what happens on the sensor? Simply fix the ISO, and you will see any shutter/aperture changes on the histogram (this means as the sensor's exposure levels change)
The default ISO (ISO200) means the sensor performs at its best (max saturation & SNR levels). Study my photon to electron graph... Study the above article about dramatic skies and the photons to electrons graph. It takes a while to fully appreciate the value of working with theoretical information. Please ask again if sensor saturation is still not clear to you. Yes, the sensor is fully saturated (max DR, IQ, and less noise) when properly exposed...
Have a look in Workspace. It's possible to set the warning levels of the histogram in the camera. These are shown with different colors in Workspace. These pre-warning colors help us when we convert raw files and edit them in Photoshop.
I hope this helped Brian.
Best
Siegfried
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