Jun 22, 2020

Photowalk and Advanced Exposure Techniques

Last Update:- 27th May 2024

My wife and I were driving past the old town of Rapperswil at the far end of Lake Zürich. Returning from our appointment, we decided to stop at Rapperswil and spend an hour or two in this lovely old town. My wife with her EM10 III and myself with my Pen F and 12-50mm f3.5-6.3 EZ lens.

I also wanted to try my Gossen light meter. The idea was to try the Gossen with more demanding exposure techniques like ETTR for street/city photography. (Walimex is a Gossen)


Olympus EM1 II w 30mm Macro, 2x FL600, mini studio, RC Mode.


Regular visitors to my blog know I've been on a journey studying the camera's image sensor, types of image sensors, the size and capture theory, and different exposure and focusing techniques.

While searching for information for my new Gossen, one thing led to another, and I came across the Sekonic YouTube presenter, Joe Brady. In his videos, Joe demonstrated the benefits of using external light meters with modern cameras. Joe convinced me to add the Gossen to my exposure toolbox. The Gossen was tucked away in my photography "to-do" list until I saw Joe's videos.




It's now 3 years since I started studying image sensors. In that time, I read different articles on DPReview and participated in heated forum discussions. I always compared the information I received to theoretical and technical articles published by engineering schools, image sensor manufacturers, the European Machine and Vision Association, and other enthusiast websites. 

As in most situations, finding that one thing that matters needs unpacking much fluff and talking. Without getting too much into the sensor size debate, those who did change from one format to another know it's way more than the size of the sensor or pixel area. The 3 factors we should consider are buying/selling costs, the size and weight of camera equipment, and the available lens offer.

Focussing on one thing, I discovered the key to optimum image quality is having the image sensor at its optimum SNR and saturation level. (Figure 1) It became clear that the digital camera is not a digital paintbrush. The ideal SNR is specific and available in a small operating window. This motivated me to shift the creative part of my digital photography to the post-processing phase.

The image recording phase is simply a data-collecting phase and nothing more. The goal is to select the "best" exposure mix to push the sensor to its ideal performance window. This "ideal" performance window happens when the sensor reaches optimum SNR or Saturation levels. (See Figure 1) The sensor records more tonal data with the lowest visible noise at full saturation.


Figure 1.


It took my wife and me 2 hours to complete our photo walk in Rapperswil. I selected an ISO of 200. The cloudy conditions would benefit from the higher DR at ISO200. I started with an aperture of f5.6 and aperture mode. That meant I had to carefully select my focus point and monitor the histogram when using ETTR or upping the exposure. This process of monitoring and adjusting the exposure is quick and takes seconds. The photographer's experience in advanced exposure technique guides the decision to use an ND or Polarizer filter, stacking or bracketing, or the camera's HDR function.


Olympus Pen F with 12-50mm ISO200, f5, 1/500 - Raw file converted in Photoshop (only basic settings).

I adjusted the exposure of the above scene with the Gossen. Study the histogram. The Gossen's exposure reading was the equivalent of the camera exposure at +0,3EV. The dynamic range of the scene was influenced by the clouds. For example, one has more or less clouds in the exposure frame when pointing the camera up or down. With the camera's exposure reading pointed toward the clouds, the street-level exposure and SNR decrease, and the visible shadow noise increases. 

Not that shadows generate image noise. Less reflected light on the sensor means a smaller SNR, less tonal data, and more visible noise. Interestingly, the Gossen exposure meter is less affected by clouds because its FOV is 180 degrees. The camera's FOV is linked to the focal length of the lens...


This is the same image edited in Luminar 4 - One can see how the camera handled the DR well.


The above image is an edited version of the RAW file. While editing the RAW file in Photoshop, I knew the RAW file had enough tonal data, which enabled me to push the RAW file a little more. 

I upped the camera's exposure with the aperture "gain" option (image below). The histogram shifted to the right, and the street-level image brightness improved with the higher exposure level. My final exposure benefitted from an ETTR gain of +1EV. Moving the histogram to the right means the darker street level benefits from more tonal data and less noise. An increase in tonal data benefits the complete tonal range. Exposure techniques like HDR increase the tonal data even more. I also used the camera's over and underexpose indicators to monitor highlight and shadow clipping. The Olympus histogram is flexible enough to help us find the best possible exposure mix with ETTR. 




I rarely go for clipping-free exposures. The brighter clouds did clip a little in the above example. I was OK with that because most people wouldn't recognize any clipping. I apply the same rule for darker shadow areas. I learned it's better to clip (turn black) some darker areas and prevent non-critical areas from showing noise. This is similar to what Panasonic does for filming. For example, Panasonic allows us to work with a smaller tonal range of 15 to 256. Study the OOC jpeg below. 


This is what the camera's jpeg looks like when one applies an ETTR of +1EV.


The image below is the edited Raw conversion of the above jpeg. I pushed the sensor to its optimum saturation and SNR with my exposure mix. This allowed me to "push" the conversion of my raw file a little more. Study my articles about Workspace and the Enhanced Raw Format for more.

Those preferring out-of-camera "ready" JPEGS should read the following. The secret is to treat your Raw and JPEG files differently. The RAW file can be pushed to have more tonal data with less visible noise and can be re-adjusted to mimic the scene in post-editing. Jpegs are different and benefit from more accurate exposures. For example, we can tweak the gamma curve of Olympus cameras. This is done with exposure compensation and the Gradation and highlights/shadows functions.

The following settings allow us to create JPEG profiles in the cameras. For example, use the mid-tone slider to correct ETTR adjustments and the i-Enhance Picture Mode to activate the Olympus image quality features. The gradation function improves shadow details and limits clipping, and the highlight and shadow sliders are used to add contrast or manage the shadows and highlights.


Olympus Pen F with 12-50mm lens - ISO200, f5.7, 1/250 (+1EV ETTR) - Raw file converted and edited in PS and Luminar 4.


Final thoughts on saturating the image sensor and ETTR

Study this article to learn more about ETTR or what it means to "flood" the sensor. Study this article for more on how to read the DxOMark image quality database, and read this article discussing the 4 things that will improve your image quality. The image creation process for the above image starts by reviewing any depth-of-field (DOF) or movement requirements linked to the aperture and shutter mix. The next step is to optimize the sensor. I used the following camera setting for the above image:
  • ISO200 (Manual setting - see intro text))
  • Shutter speed of 1/400 (Aperture-Mode - shutter speed was selected by the camera)
  • An aperture of f5,6 (The photographer's choice in Aperture Mode - f5,6 creates a large DOF)
  • I used my Gossen exposure meter reading with an ETTR of +0,5EV to up the SNR.
  • The histogram confirmed that I could shift the histogram to the right with +0,5EV.
  • I used the histogram's under/overexposure warnings to find the final exposure mix.

The final step focuses on the reflected light reaching the image sensor. The aim is to expose the sensor optimally with techniques like ETTR or stacking. Which of the above exposure settings would you change if you had to increase the shutter speed? I manually selected ISO200. We also know that the ISO does not control the reflected light to the sensor like the aperture/shutter mix. 


Something we haven't discussed much is to 
think of the aperture as gain.


The target is exposure and not DOF when using the aperture gain effect. That means doubling the reflected light to the sensor for every 1EV aperture increase. This exposes (floods) the sensor with information. The question is, how does this affect the DOF? Something that should be talked about more is the 2-stop DOF (Depth-of-field) advantage of M43 cameras.


The "starting" depth of field was set for the city scene. It's, therefore, safe 
to slightly increase the aperture (gain) to control the image sensor. 


This M43 (DOF) advantage varies from application to application, like macro, landscapes, or city scenes. Always experiment and use your photography experience to select the best exposure mix. Photographers migrating to M43 cameras tend to prefer higher apertures. For example, they will use f8 to f11 for landscapes, whereas f5.6 to f7.1 is enough for landscapes on M43 cameras.


Pen F with 12-50mm, ISO200, f5.1, 1/200 and +0.3EV (ETTR)


Full-frame cameras have more background blur but a smaller DOF. Full-frame photographers disagree on forums, while it's nothing new to find serious full-frame photographers using techniques like focus stacking in more critical DOF applications like cityscapes or landscape photography.

One needs to break free from the commercial "background blur" hype to learn why the M43 aperture is one of the M43 segment's most exciting features. The key to unlocking this strength is re-thinking how we apply the aperture with crop sensor cameras. A depth of field aperture of f5,6 is good for city and landscape photography. The key is having the correct focus point. See this article.

It was safe to add +0.5EV reflected light to the sensor for the first image of Rapperswil. The brighter street level and 50% more reflected light onto the sensor didn't affect the original DOF much.

Consider how marketers distract M43 photographers by shifting the focus to equivalence and background blur. They effectively confuse and prevent crop-sensor Photographers from benefiting from the DOF or the unique sensor saturation or "gain" advantage of M43 cameras. Instead, M43 photographers focused on diffraction, noise, and keeping the ISO below 500.

If you want to experience the full benefit of aperture gain and how it impacts sensor performance, apply this technique to older M43 or smaller sensor cameras like the Olympus X-Z2.




The takeaway is the aperture changes the reflected light (gain) or DOF. Exposing to the right (ETTR) means more aperture gain, especially in poor light conditions with slower shutter speeds and higher ISOs. One needs as little as +0.5EV to improve the sensor's saturation. A full stop will seriously flood the sensor. More reflected light means a better SNR, more tonal data, and less Visible Noise.

It helps to practice with older 12 and 16MP mirrorless or compact cameras. The benefits are more visible with older image sensors, and it also helps to master the DOF versus gain principle. 

Does later 16MP and 20MP sensors also benefit from this technique? Absolutely, but the differences are less visible for newer versus older sensors. The camera's auto-exposure algorithm saturates the sensor more with newer Olympus cameras. See this article about Olympus' safety headroom.


Olympus Pen F with 12-50mm f3.5-6.3 EZ lens, ISO200, f5.0, 1/350, +0.3EV (ETTR) - Raw file converted in Photoshop.

May 22, 2020

ETTR summary plus a real example

Last Update:- 24th May 2024.

Much has been written and said about ETTR. Enough for most photographers to see the value in having this technique. Unfortunately, this is not the case because YouTube and forum experts continue to make wild claims about sensor size. This resulted in a powerful exposure technique being lost in a cloud of "size and capture" confusion. This article gives a brief overview of marketing.

This article discusses the 7 points photographers should know about digital cameras.


Olympus EM1 II with Leica 25mm f1.4 lens - ISO6400 f7.1 1/13Sec with ETTR - Enhanced Raw file converted in WorkSpace and edited in Photoshop.

What is ETTR or Exposing to the Right?


ETTR means the best possible aperture, shutter speed, luminance, and ISO mix. The goal is a higher SNR and a saturated image sensor. The ISO function does not control the reflected light exposing the sensor, whereas the shutter and aperture physically control the reflected light. Enough reflected light means a saturated sensor, higher SNR, more tonal data, and better image quality. This article discusses luminance, illumination, reflected light, and the direction and types of light.

What is the role of the ISO function?


We manage 4 of the variables in the exposure formula. These are the aperture, shutter speed, ISO, and luminance. The ISO does not change sensor sensitivity. It amplifies the image signal and the noise coming from the sensor. See my other articles for more about the sensor's noise floor.




I use a fixed ISO to match the ambient light in buildings while adjusting my aperture, shutter speed, and luminance (flash) mix to find an optimum exposure to saturate the sensor. Study this article for more about the ISO, aperture, shutter speed, and illumination. This article reviews the ISO as an image signal amplifier or brightness adjustment. One can also use the ISO strategically...


The most critical variable impacting image quality is understanding the ISO. 
Avoid Auto ISO settings and learn how to manually set the ISO.


What are the benefits of ETTR?


The many senseless "discussions" about photons, bigger pixels, and sensor size mean nothing if it doesn't improve your existing camera. The only variable we manage is sensor saturation. The average consumer camera records more tonal data (image quality) with a saturated sensor. Digital cameras typically double the tonal data for every 1EV of ETTR. That means the histogram moves to the right, the sensor's Saturation and SNR improve, and the camera processes more tonal data.


The under-exposed version has approximately 75% less total data.

How does one apply ETTR?


I only use ETTR for challenging situations. A fixed Exposure Shift of up to 1EV is often enough. I also prefer Aperture or Shutter Mode with a fixed ISO. For example, an ISO of 64 or 100 is perfectly OK in most daylight conditions. I also use my ISO function strategically because we know it adjusts image brightness and is part of the exposure formula. A fixed ISO lets us use exposure compensation for ETTR while monitoring the sensor's saturation and SNR levels with the histogram...


A copy of the Olympus EM1 II display when the camera selected the exposure.

Olympus cameras use a built-in safety Headroom to prevent the sensor from clipping. For example, the camera's exposure meter shows a correct exposure while the sensor is not saturated. It's possible to manage this safety headroom with ETTR. For example, one can increase the exposure by up to 2EV with the blue sky as the background. Another scene might limit the possible ETTR compensation to 0.5EV steps. The camera's exposure meter will show an overexposure reading with ETTR. We correct this in Workspace with the exposure compensation (ISO) function.

Study the image below. I used an ETTR of 1EV. There was enough available dynamic range to increase the exposure with another 1EV. This is how much the camera meter undersaturated the sensor. The processed tonal data in the shadows suffer most in these conditions...


A copy of the Olympus EM1 II display with an ETTR of 1EV.


General comments


Photographers are told that ETTR only works at the camera's base ISO. I disagree because digital cameras are designed to capture more tonal data with the histogram to the right, irrespective of the ISO value. Social media "experts" argue the dynamic range is too little at higher ISOs. The dynamic range does reduce at higher ISOs. Does this mean we shouldn't use ETTR, or should we simply manage the situation? A workable solution is to ignore these paid experts (promoters) and improve your know-how while having more experience from photographing regularly...

Tip:- The ISO effectively adjusts image brightness and not the exposure.

In terms of exposure, the following basics are critical:-
  • The aperture and shutter are the only variables controlling the light to the sensor
  • The ISO function only amplifies the image signal coming from the image sensor





Do this quick ETTR experiment:-

  • Find a scene with deep shadows and not overly bright areas.
  • Set the camera to A, S, or P Mode with Auto ISO and take an image.
  • Use the above camera settings (fixed ISO) for a 2nd image in Manual Mode.
  • Use your aperture or shutter speed to increase the exposure in 0.5EV steps.
  • The histogram shows what's happening on the sensor with a fixed ISO.
  • Download the images to your PC and study the shadow areas for noise.




Conclusion


The camera's histogram tells us when the image sensor is desaturated at base ISO or when the camera uses its DR safety area. This "safety headroom" is one of the main reasons for M43 cameras having visible shadow noise. Knowledge and experience taught me it's safe to overexpose Olympus cameras with up to 1EV (ETTR) and correct it in Workspace. The secret is a fixed ISO and watching the histogram for highlight clipping while applying ETTR (adjusting the aperture/shutter).




The most important aspect I learned from my M43 journey studying sensors, testing Olympus cameras, and writing articles is image noise has become an effective counter-marketing strategy to discredit the M43 photographers. I recently tested the impact pixel area has on 15 different cameras. The shadow image quality differences were surprisingly small. You will find the article here.

Do I often use ETTR? I have many Olympus cameras in my collection. I photograph almost every day with one of them. I regularly try something new and use these cameras while preparing my articles. I am confident the Olympus engineers selected excellent 16MP and 20MP sensors. This means these sensors perform well in a wide range of applications. I occasionally apply ETTR but found that my understanding of Olympus cameras is more valuable than focusing on noise and ETTR...


Sony A7 III with 50mm, f1.8 lens - ISO25600, f7.1, 1/30sec, and ETTR - The Raw file was edited in PhotoLab 3 plus PhotoLab 3 noise reduction.

Apr 25, 2020

Photoshop, PhotoLab, Luminar & WorkSpace

Last Update: 28th Nov 2020

Most photographers are familiar with Photoshop, PhotoLab 3, Luminar 4, and WorkSpace. Others use image editors like Lightroom, ON1, Capture One, or Topaz. In 2005, when I bought my first digital camera, I learned all about image editing with Photoshop Elements 2 and Paint Shop Pro.

With this article, we will take a quick look at Photoshop CC, PhotoLab 3, WorkSpace, and Luminar 4. We discuss some of the strengths and weaknesses of these editors and how they complement each other when used together in post-processing.


Olympus XZ-1 - edited with PhotoLab 3 and Luminar 4 (Sky was replaced with Luminar)


When evaluating different cameras, it is always important to rate them on how edit-friendly each camera's images are. You probably think, why do that? Some brands are just more flexible during post-processing. For example, Panasonic is known for its sharp images. That said, older Panasonics had color issues like skin tones, greens, and blue skies. It was difficult to correct these faulty colors. More recent models like the GH4, GH5, and the G9 improved significantly.

In terms of color and editing, my favorite brands were Olympus and Canon. The editing flexibility of these brands is excellent. When Olympus launched the EM5 MKI, it felt like the dynamic range was infinite, especially when compared to the older EP3 or the Canon 700D, which I also used at the time.

Paging through my EM5 image collection and studying them, I was glad that I always used the JPEG + RAW option. If you ever considered using raw files, my advice is to start as soon as you can. The reason simply is, that raw editors continue to improve every year...

Olympus EM5 w 12mm f2 Jpeg file,  ISO200, f5.6, 1/1000 (No editing - as-is from the camera)


The above image is not really great but interesting in terms of post-processing. The reason is the sky was not clear and the position of the sun was not good. My camera's default profile settings were set to neutral. The best would have been to take the image in the early morning or late afternoon. The reason for selecting this image was, that I wanted to push it a little and study how it reacts with the different image editors. See the descriptions below each image for more information on how I edited them.


The raw file - edited with WorkSpace


Raw file - edited with DXO PhotoLab 3


Raw file - edited with Photoshop CC


Raw file - edited with Luminar 4


The above images were all taken in Lucerne, Switzerland. As you have seen in the descriptions I edited the same raw file with different image editors. If you spend enough time editing the different images, it is possible to get them to look the same. The approach will be different for each editor, but with a little patience, you will see the results you looking for.

Having said that, working with the different image editors, you also learn the strengths and weaknesses of each of these image/raw editors. If you prefer more creative freedom I think Luminar is currently the most exciting option. On the other hand, PhotoLab 3 is very true and capable, especially when combined with DXO filters like FilmPack 5 or the Nik Pro collection.

Raw file - edited with PS then opened in Luminar as a filter - EM5 w 12mm f2.0 - ISO200, F6.7, 1/1000


That said, you should not underestimate Photoshop. It does everything these different editors specialize in. The main plus something like PhotoLab 3 or Luminar 4 offer, is the low cost, ease of use, and the fun factor. I also like how DXO does its lab tests, to measure camera and lens data. They then use this data to improve the results from PhotoLab and Filmpack. This is especially interesting for Olympus.

Olympus XZ-1, ISO100, f2.8, 1/800 (jpeg)


The above image was taken in 2012 when my wife and I visited Paris. You will see this is again not a great image because I made all the mistakes one should avoid making. For example, I pointed the camera to the sky, and the camera then focussed (exposed) on the clouds. The street level was underexposed with more shadow noise. The little Olympus XZ-1 is way more capable when exposed correctly. 

You will see from the other examples, and how I applied different editing styles. Some I edited like I did with the above examples and the final image, I opened the raw file in PhotoLab and then transferred the result to Photoshop. From Photoshop I used Luminar as a filter to replace the sky. This enabled me to apply and combine the unique strengths of each editor in one editing session.

Olympus XZ-1 - raw file edited in PhotoLab 3


Below you see the different image editors I used and the order in which I spent time with each:-

  1. Photoshop CC (My main creative and complete image editor plus raw converter)
  2. DxO PhotoLab 3 (Probably the best raw editor, especially for Olympus)
  3. Olympus WorkSpace (Excellent raw and basic jpeg editor, free for Olympus owners)
  4. Luminar 4 (The AI functions are truly amazing plus layers make it a more complete editor)

I also use Aurora and DxO FilmPack 5. Years back I started with Adobe Photoshop Elements and through the years I kept an updated copy of Elements. If Adobe added curves to Elements, I would cancel my subscription and only use Elements.

Olympus XZ-1 - raw file edited in WorkSpace


When you click on the above image it will open in the web viewer. Scrolling through the different images you will see the image cropping and keystone results are different for each editor. No real reason other than I should have done a little more effort with each.

My typical raw file editing sequence looks something like this:-

  1. In some cases, I open and edit in WorkSpace, then export to PS
  2. I edit in DXO PhotoLab 3 and export to PS for difficult scenes with noise 
  3. In most cases, I start with the raw file in PS and also complete it in PS

I prefer to have Luminar 4 and FilmPack 5 as Photoshop filters. I seldom work with Luminar 4 in standalone mode. The reason is the included image organizer. This is also the reason I do not use Lightroom... It would be so much better if Luminar and Adobe gave us the option to stop/cancel the organizer. I have a great system that works well for me and never saw the benefits of changing.

XZ-1 - edited in PhotoLab, Photoshop & Luminar 4


Different editing styles will apply to different applications. When editing for prints I am much more conservative and I will focus on colors and details aimed at printing. Editing for the web is different and more fun or experimental.

Taken with the Olympus EM5 with 14-150mm lens - ISO200, f9, 1/400 (Edited and prepared in Photoshop)


Photoshop is by far the best tool to prepare and edit panoramas. The above image consisted of 6 raw files. Photoshop compiled the final panorama in raw and I was able to do my normal raw routine with Photoshop. Interesting about Photoshop is the Content-Aware tool and how it fills in the edges in the final panorama.

The above image was edited in Luminar as a Photoshop filter, changed the sky, and changed various AI settings


The above panorama and the next 3 images were all taken in Miami. Using Luminar, I replaced the sky in the panorama. The sky replacement was not perfect because the replacement sky was sized for a single image and not a 6 part panorama. The raw post-processing with the next 3 images started in PhotoLab 3 and then exported to PS. From PS I used Luminar 4 as a filter to edit my special effects.

Olympus EM5 w 14-50mm, ISO200, f7.2, 1/640 (PhotoLab 3 plus Photoshop plus Luminar - no sky replacement)


Olympus EM5 w 14-150mm, ISO200, f6.3, 1/800 (PhotoLab 3 plus Photoshop plus Luminar - no sky replacement)


Taken with the EM5, raw file edited - I let you guess what was done with this image...


The next two images were taken in Germany in a lovely village close to Frankfurt. You can literally spend weeks in this village and create many masterpieces...

Olympus EM5 with 14mm f2.5 - ISO800, f3.5, 1/60 (Raw edited in PhotoLab 3 and completed in Photoshop)


The same image was edited in Luminar - sky replacement, added glow, and a few other AI adjustments


The next two images were taken in 2007 when I visited Nürnberg. The images were taken with the G7 and the E410. The E410 was in raw format and the G7 was in jpeg format. When comparing these results with those I edited in 2007, the difference is day and night. One can literally spend hours going back a few years and re-process raw files...

Olympus E410 with 14-42mm Kit Lens, ISO100 - Edited with PhotoLab 3 and Photoshop


Canon Powershot G7 - ISO80, f4.0, 1/500 - Edited with PhotoLab 3, Photoshop, and Luminar 4


The time I spent editing the different images in this article was less than 5 minutes each. Normally I spend more time per image. The fun factor of working with these different editors is huge. One of my next projects will be to take more exciting skies for Luminar 4. This is probably the most fun aspect of Luminar 4.

Do you need to have all these different editing tools? Any of the editors discussed in this article is great and more than enough. If I had to recommend an editor or filter option, my choice would be Luminar 4. WorkSpace combined with Luminar 4 is more than enough and really powerful.

Olympus EM5 with 12mm f2.0 - ISO200, f9.5, 1/500 - (Raw file edited in PhotoLab 3)


Edited in PhotoLab 3, then transferred to Photoshop and sky replacement in Luminar 4


When you study the above image you will see I replaced the sky. Can you see the mistake? This is an important question because the final result should always look realistic... See my Instagram account for more examples. (TIP:- look at the sun)

The images below were all taken in different locations like South Africa, Switzerland, and Sardinian. I used different editing combinations with different editors...

Panasonic LX100 - ISO640, f5.6, 1/60 - Raw file edited with PhotoLab 3


Olympus EM5 II with 14-150mm MKII - f5.6, 1/640 - Raw file edited with PhotoLab 3


Olympus EM5 II with 12-50mm - ISO200, f5, 1/200 - Raw edited with Photoshop and refined in Luminar 4


Olympus EM5 II with 17mm f1.8 - ISO200, f4.5, 1/1000 (ETTR +0.7EV) - Raw edited with PS and Luminar 4


Oly E-620 with 18-180mm - ISO100, f11, 1/100 - Raw edited with PS, then edited in Luminar 4 (no sky replacement)

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