Olympus E-M5: Exposing (to the right) and Lightroom 4.1

I posted previously an article on "Exposing to the Right" (ETTR) with Olympus E-P3 RAW images. You can read it here. This blog is based on the same fundamental idea. My previous article was both praised and scorned. The latter came mostly from people who believe in a method to do ETTR known as UniWB. UniWB is a clever method of addressing limitations you encounter with practically every digital camera if you want to expose to the right. With it you have to endure either a green or a black and white live view viewfinder, and I am not too happy with either. Also it is based on using histogram which I´m not happy with either. This method I am using is based on using highlight warning blinkies as exposure meter: they are both easy to see, very graphical, and show what´s actually happening in your image, spot by spot if you want to. This method applies for Olympus PEN cameras since E-P3 (plus E-PL3 and E-PM1) and OM-D E-M5.

Since I got Olympus E-M5 I have practiced it quite happily with the same settings as with E-P3. Lots of people have written to me to write about ETTR with E-M5. I wanted to wait until Lightroom is ready for it because this method is set to be used with Lightroom. Of course you can tweak it for other RAW converters by varying camera configuration settings. At first Lightroom 4.0 was a pile of bugs. There were two Release Candidates for Lightroom 4.1, and now we have a quite satisfactory final version of Lightroom 4.1. It still has some instability issues left (and a few shortcomings with Photoshop integration if you have not updated to Photoshop CS6) but they are no more important here. What´s more important is that Lightroom 4.1 gives you more control on your image relative to its final use.

E-M5 configuration

Lets start with Olympus E-M5 configured like this:

Shooting Menu 1 > Picture Mode > 4 Muted > Contrast -2, Saturation, -2, gradation: Normal

Custom Menu D > Info Settings > LV-info > Highlight&Shadow:On, Histogram: Off

Custom Menu D > Histogram Settings > Highlight: 245

Custom Menu D > Live View Boost: Off

Custom Menu G > Color Space: Adobe RGB

Auto white balance, if used, must be set to neutral: Custom Menu G > Auto WB, Keep Warm Color: Off

Exposure

I adjust my exposure until the red warning color just appears on my chosen critical tone area. By critical tone I mean the brightest area in my image where I want to have definition of tones if the image is printed. In principle, this allows a 1/6-stop accuracy at best, but in practice, the reference tone is very close to the value of 96% almost always when the image opens in Lightroom Develop module. Same critical area will be at RGB value 245 (Adobe RGB or sRGB) in the final image with very little need to adjust as seen below. I do not need to use histogram while shooting, I do not need to check captured images, at least not because of the exposure. 

I exposed this target (right half of Spyder Checkr) with E-M5 so that red highlight warning color started to blink on the lightest area, which is the white patch, up left. This how it looks like imported in Lightroom 4.1 with Lightroom default settings. The only thing I have changed is that I chose Custom WB according to patch shown by cursor. I shot the target outside in sunlight using Daylight WB. You can use Auto-WB for general subjects but it is better to choose a preset WB or make in-camera Custom WB if your image has one or two dominant colors. 

(Note: What you see above is a sRGB image. That´s the only practical option to show in the internet. If you download it and measure patches, they have sRGB values and differ from what I show as measured from converted RAW file below.)

The image above shows the lightest and darkest patch measured (Custom WB, other LR settings at default). The lightest patch is very close to my aim, 96%. The image looks mostly fine but you may need to make some adjustments to darker tones if your subject had low or extremely high contrast.

In general photography subjects many times have brighter spots or areas than my critical value. They are mostly light fixtures and specular reflections where tonal definition is not needed. They may and must go purely white otherwise the image will look flat. I´m interested in where I want tones to end.   

Basically this was it. I am done with telling how I expose with E-M5 when images are opened in Lightroom 4.1. But I go on and write some more background information which might be useful to some people.

Quick-checking Color Channels

If you need to be more precise about colors everything is not done yet. Namely, some highly saturated colors may have a blocked channel as seen in Lightroom RGB preview. In this target all the other patches have definition but yellow patch shows red channel as over saturated and blue patch shows the same channel as zero with LR default settings.

Note: If shooting casual images to be seen just on monitor, I could expose even more to the right. There is some headroom left. By setting Custom Menu D > Histogram Settings > Highlight: 255 I would expose lighter by 1/3 of a stop. And even from there you could expose still a full stop more before the lightest patch would become hopelessly over saturated and blocked. I have tried it but the risk of saturating color channels beyond repair becomes too big AND the time needed to tweak the image colors grows too long. That´s why I have chosen my approach with Lightroom 4.1 as shown here. You may find Histogram Setting 255 worth trying. 

Here I have corrected those two patches to have definition in every channel by slightly lowering yellow and blue saturation in HSL panel.

Note: Actually I can use Spyder Checkr to calibrate my camera to show the colors in target correctly, but that would be a subject for another blog.

RGB Profiles and Soft Proofing

This image shows the same situation seen as Adobe RGB Soft Proof in Lightroom 4.1. Soft Proofing is a new feature in Lightroom 4. It gives you a tool to check that your image has sound values for a needed use. If your image will be printed in a magazine (or offset printing), the general workflow is to prepare and send it in AdobeRGB color space before color separation (conversion into the right flavor of CMYK). With my exposure the lightest patch goes just where the tonal definition end generally in offset printing, at RGB values of 245. Depending on paper the darkest tonal definition would fall between RGB values 16 to 30, with 16 meaning high quality glossy magazine cover and RGB 30 meaning a cheap matte cataloque paper. Instead of Histogram it says now Soft Proofing and the histogram has been changed to show values according to Adobe RGB profile. Below histogram you can see now RGB values, these here are for the lightest patch. I have copied the corresponding RGB values on each four color pick window. Gamut warning is on, as shown by the little square in the upper right hand corner of histogram. Blue patch has still some traces of warning color showing that it is just barely inside Adobe RGB gamut. RGB numbers all show definition in every RGB channel (maybe just barely but still) and they would print out nicely enough with CMYK colors. There´s more to this (Intent etc.), but what´s important, you can see how easily this method of exposing with E-M5 gives you technically very good images. 

Here we are soft proofing the same RAW file with sRGB profile (LR at default settings, same custom WB). The lightest patch has the same values (244) as with AdobeRGB profile but the darkest patch is darker. The main difference, however, is the smaller color gamut of sRGB. Five patches are covered by red gamut warning color. 

Here I have tweaked those five patches into inside sRGB gamut by using saturation sliders in HSL panel. Again: Exposure is fine but RAW image makes a lot more colors possible than can be had inside sRGB color space. This kind of mapping is also what happens if you shoot JPEG and choose sRGB as color space in your camera. Your camera maps colors inside sRGB color space. The method may be different from what I have shown here by simple means but the idea is the same.

Note: For casual images shown on your monitor there is no need to force all colors inside sRGB (or AdobeRGB, if your monitor is capable of it). You are free to have over saturated colors if you like them, but for many professional purposes colors need to be inside gamut. Also all cameras do not behave right and map colors inside chosen color space for JPEG images. Bleak inside gamut colors are not pretty enough, it is commercially better to leave colors saturated, strong and beautiful.

The last example comes back to my reasons to do things my way. My favorite printing paper for my pigment ink printers is Canson Infinity Platine Fibre Rag. Here we have again the same target shot with Lightroom at default values (same custom WB). All the colors are beautifully inside Platine Fibre Rag gamut with this profile for Epson 9900 printer. What coud be better? Perfect exposure for the lightest tones and even strong colors have full definition out of the box. I only need to tweak dark tones as needed. Most of the time I do a lot more with my images but that´s not out of necessity. 

-p- 

Update on June 22, 2012 at 15:35 by Pekka Potka

Two examples of lots of gain with no pain

This morning, while walking the dog, I shot a couple of comparisons to show the difference in details and noise between images that are exposed "normally" with E-M5 and "my" images. "My" meaning of course using settings and blinkies as said earlier in this blog.

Example one:

Same view shot first at camera´s (E-M5) autoexposure and secondly so that red blinkies just lit the trailer´s bright side. Both shots opened here into Lightroom 4.1 with Lightroom´s default settings. Readings under histogram are from trailer´s white side.

Next I clicked Auto Tone for both images. As you can see, Lightroom gives almost exactly one stop difference between needed adjustments. Again readings from the same spot from white area. I could have gone further here with tweaking both images but doing so has no real relevance here. Like you also can see white area is not really white but has details like over painted markings. These highlight details would be quite similar after any reasonable tweaks in both images. Looking at other things in these images, you notice that I have applied an overly strong but equal combination of sharpening and no noise reduction for both images. This to illustrate how ETTR image is clearly superior in blue sky and in yellow and green surfaces. It has a lot more headroom for tweaking. These are 100% crops.

Crops from upper right hand corner show how darker but still medium blue sky behaves. Same overly strong sharpening to better show the differencies. ETTR image keeps wisps of cloud much better intact.

Example two:

Again the other picture shot with camera´s autoexposure but this time the other on was exposed to the right up to the last setting where red blinkies did not light up the lightes part of sky. Both images here opened into Lightroom 4.1 with Lightroom´s default settings. This example is to show the behaviour of darker tones.

And again, I just clicked Auto Tone to normalize images. These details from the back of chair are 2:1 screen captures from Lightroom. All noise reduction (color and luminance) is again off (at 0) and strong sharpening applied. As you can see ETTR image shows much more detail and less especially color noise. What you would get is even more detail with similar noise reduction in every image. The more you tweak the greater the gain from ETTR would be. Also note how much more details with smoother tones the background (easiest seen on the right) shows.

-p-  

Expose to the right, ETTR - with E-P3

This blog is really about my experience with the Olympus E-P3 camera (and to some extent E-P2 before it). This is also about the advantage, that is obtained when shooting in RAW format, and always exposing as much as possible. The expression "as much as possible" does not mean here overexposing. What, then, is overexposure?

Gamma

Because of this issue of exposure I´m not going directly to the E-P3, but we need to discuss a few things. First a look at the the crucial difference between the RAW file and the film. Ignoring this difference leads into blurred concept of overexposure or correct exposure. The difference is gamma curve.

In practice, in almost all digital cameras, AE follows the old film era definition. It is based on the average reflectivity of the object. The camera may be set to expose by either 12% or 18% reflectivity. Film has a gamma curve, which is kind of a ski hill-shaped curve. On the top it is bright and curve is gentle, the middle is steep, even slide and down hill evens out into shadows. Most pictures appear to be good, when its central tones have a good contrast. Dark colors must not suddenly change into black and light shades must not go into white all of a sudden. Such sharp edges do not seem natural. Therefore, tonal changes are slowed down at each end with gentle arc. For film photographers it is most important to use the contrasty middle tonal range as completely as possible. According to this need for visual naturality different types of film require somewhat different exposure. Slide films need less exposure to prevent highlights from becoming white (to be overexposed), and negative films must not be exposed too thin and prints appearing too dark in shadow areas (would be underexposure).

For the majority of subjects, all goes well, if it is exposed according to the camera's meter. Only experience tells when, in what direction and how much it is necessary to deviate from the camera´s value.

RAW

RAW file is different from the film in that it does not have the same gamma curve, it is linear. From white to black, there goes a straight line with no curving at either ends. The requirement of naturalness (to the human eye) in the image, is carried out in the RAW conversion when RAW file is converted into pixel file and saved for example as TIFF or JPG format. Then the final image gets a gamma curve, and this curve is adjustable by the user in every good converter. However, this curve is not always visible as itself in most converters, only the effect in the image is visible.

Now, one could ask where's the difference. The subject is just exposed at the middle (or somewhere there) of that straight line, gamma curve is included in converter and all is well. Actually that is just what most photographers are doing - and at the same time they are wasting a significant part of tones from their images.

Tonal values in a RAW-file

In the case of RAW file we need to discuss bits in images. Bits tell us into how many tiny levels our direct line is divided. And it must be divided, otherwise we would not have a digital file. The overall impression is still a straight line, because there are so many levels. Typically, a modern digital camera has a 12-bit (per channel) converter, which converts the sensor's analog (linear) signal into digital (small steps in straight line). The best cameras can have a 14- or 16-bit converter. This does not change the issue at all, the same scale from white to black is only divided into larger number of smaller steps.

A 12-bit image consists of 2 ^12 = 4096 possile steps or tonal values from white to black. At this point, we unfortunately must say goodbye to the linearity of tonal distribution: tone values are not evenly distributed into bits. Starting from white towards black, half of the ALL tonal values are inside the first bit. For simplicity, we can speak in photographic terms, ie steps in aperture or shutter speed scale: One full step in opening the aperture (eg, F5.6 -> F4) or an equivalent increase in exposure time (eg, 1/60s -> 1/30s) increases the amount of light to double. Then the first step starting from pure white includes half of all possible tones in a RAW file! In a 12-bit digital camera, the first step starting from white has thus 2048 possible tonal values (per channel), the next step has 1024 possible tonal values, again the next step has 512 possible tonal values, and so on.

Now you may (hopefully) no longer think that it is indifferent to where on this scale of tonal distribution your RAW file is exposed, if you want the best possible tonality in your image!!!

Above we have two RAW images as they are opened in Lightroom 3. The upper one is exposed according to what camera meter (AE) says and the second is exposed to the right. The change in exposure is +2 steps. Below images we have their histograms in Lightroom with default settings, left camera AE and right my ETTR version.

 Next pair of images has the same images normalized. Mainly I clicked Auto plus changed slighty sliders. Again above is camera´s version and below ETTR version. Histograms also in the same order as above. The most obvious differencies are 1,8 steps more exposure in camera´s version and  more blacks for ETTR version. There was no need for any change in exposure for ETTR image. A quick glance reveals not much difference in images, but they have. The real clou is seen in the next pair of images.

The clou is the amount of detail and noise. These 100% crops are in the same order as above, and neither has any luminance noise reduction. ETTR is one of the most efficient ways of minimizing noise in shadows and elsewhere. Note also how two stops more exposure did not diminish detail in light ares, it only gives more detail as s/n ratio gets better.  

Histogram and exposure

The histogram reflects the distribution of tones in the image. The histogram has white on the right side and black on the left. Therefore, we can say that in the histogram the first step from the RIGHT has half of the possible tonal values of the picture.

What does a histogram in a digital camera show? It does not show the tones of a RAW image, but tones of a JPG preview calculated from a RAW image. These tonal values are dependent on the camera's contrast and saturation settings. The histogram might show over- or underexposure (or both), even though the sensor itself would have plenty of exposure latitude left. In addition, the histogram is affected by the selected color space. In particular, the sRGB color space is narrower than the sensor color space. When it is selected, the RGB histogram displays too often saturated colors that do not actually exist in the RAW file.

Worse still, the histogram is not even a good ETTR-exposure meter, because it reflects the image globally and not its individual tone areas. It does not directly tell what is the exact area in the image, which is now going blocked. ETTR-exposure requires the use of each pixel in the image area as a separate light meter and display.

Finally, the worst of all: a traditional reflex camera´s exposure metering (prior to taking a photo) is even more problematic in terms of shooting in RAW. It does not understand anything about the behavior of the sensor. They are two completely different things.

Expose To The Right, ETTR

As much as three quarters of possible tonal values of a RAW file are in the first two steps from the right. This should be a sufficient reason for every RAW photographer, to expose as to the right as possible, without burning the light tones of the image, of course. This method deviates from the traditional concept of "correct" exposure. ETTR RAW file can appeear be too light when opened into a converter. The converter is used to extend the tonal range into dark direction until the tonal range is as desired. In most cases, successful exposure means that the brightest tones of the image do not need to be adjusted at all. The resulting  image has richer tones and is even significantly cleaner regarding noise.

ETTR has been also criticized or denigrated in online blogs. The problem is not the idea itself, but the cameras. Only few of the cameras provide photographers with a good tools for reliable control of ETTR. Without control, there is danger of overexposing the sensor, and the image is beyond repair. ETTR does not always mean more generous exposure than the camera's exposure meter indicates. Exposure may be also less when the subject has lots of contrast, but even then the exposure goes for the lightest tones.

ETTR means that you should set the ”weakest" settings that can be found in your camera: lowest contrast and saturation as well as a widest color space. With Live View cameras exposure control with sensor feedback is possible before exposure. With reflex cameras exposure can be seen only after the exposure. The quality of information received depends on how well or poorly the camera settings in imitate RAW files. In addition, all the automatic adjustments (Highlight, Shadow ...) which shape the gamma curve must be switched off.

The second ETTR example is again exposed for the lightest area in image and that is the lightest details of relief. We have now almost a one step increase over camera´s meter. Histogram and sliders are here at Lightroom´s default. Lightroom´s warning colors show ares where at least one RGB channel is blocked at Lightroom´s default gamma (2.2). 

This before/after pair shows details from the lightest are in the image. On the left are default settings and on the right you can see how two tiny moves in sliders fix the toe and shoulder of gamma curve so that nothing is blocked. ETTR does not lead into more work at post, vice versa

Shooting JPGs

As a clarification: ETTR is not applicable when shooting JPGs. It is not possible to ETTR a JPG file and darken afterwards unless subject contrast is so limited that it can be included in the straight part of gamma curve. Even then, most likely, light tones show banding

ETTR for me is always observing the lightest non-specular tones in image. Specular highlights and reflections may and should go white to give the image the right tonality and contrast. In this example ETTR has led into one step "over exposure" compared to camera AE. In reality this exposure is correct and the engineer who designed my camera´s AE has it wrong. It is a matter of taste where is the limit or start of specularity. It can be tweaked with a tiny change in Lightroom, if needed. Otherwise the image is OK.

Olympus E-P3 and ETTR

So, using ETTR might lead into struggle with inferior equipment. I learned ETTR however during my profession as advertising photographer in the late 90's. The tools then were Leaf three shot digital backs and Leaf software. With them and studio flash equipment it was possible to set the exposure at 1/20-stop precision exactly where it was supposed to. Later PhaseOne CaptureOne allowed the same in other cameras. But doing so demands shooting tethered.

Beyond these devices only the Olympus VF-2 viewfinder gave me a new hope toward guaranteed ETTR shooting anywhere, anytime. With E-P2 I learned to observe the viewfinder image and see when exposure at highlights was as wanted. It demanded these camera settings:

Shooting Menu 1 > Picture Mode > 4 Muted > Contrast -2, Saturation, -2, gradation: Normal

Custom G > Live View Boost: Off, Color Space: Adobe RGB

Setup Menu > VF-2 Brightness: Experimenting until I learned the appropriate setting. After that Custom D > Info Settings > Histogram: Off

This was just a start, because human eye is really not a good instrument, it is affected by the overall brightness of the scene. I had yet to check the captured image in the VF-2.

The Olympus E-P3 finally fixed these deficiencies, because it has an adjustable highlight and shadow warning by colors in viewfinder image, that is, before the exposure. This control is set at:

Custom D > Histogram Settings > Highlight: 245

Auto white balance must be set to neutral:

Custom G > Auto WB, Keep Warm Color: Off

Now, I adjust the exposure until the red warning color just disappears from the critical tone area. In principle, this allows a 1/6-stop accuracy at best, but in practice, the reference tone is very close to the value of 96% when the image opens in Lightroom. Same area will be at RGB value 245 in the final image with very little need to adjust as seen above. I do not need to use histogram, I do not need to check captured images, at least not because of the exposure.

I do not know of any other camera body, which gives me such a perfect exposure control with the same precision and certainty. E-P3 is my ETTR King!

-p-

My New Rig

I have used Olympus PEN-system since summer of 2009. With E-P3 and new Olympus 12 and 45mm lenses it has grown into a matured level for me. Image on the left has everything I need for over 90% of my images. 

I have travelled a road from 35mm film system cameras to medium and large format cameras, from there  to best digital backs and 35mm size digital system cameras. As smaller cameras I have tried all kinds of point and shoot cameras (both film and digital) and APS-C size digital system cameras. This does not mean constantly leaping from camera or system to another but owning tools according to needs.

Every camera is a compromise. You get something and lose something. During my professional career sheer quality with the best workflow was the prime qoal. Issues like portability, weight or size were not very important for most of time. 

Now I do photography to express other things and need a tool to suit my way of doing it. I want to be able to print with no compromises in quality in A3 and A2 sizes and high quality up to A1 or A0. But I want also portability. I always want to use a viewfinder, keep looking through it without any need to chimp or because of camera. I need a camera that can be controlled without looking at buttons.

I was very interested in Olympus PEN -system since the beginning in 2009, used it and learned to get every drop of quality out of it. E-P1 and E-P2 felt like my system even though lack of prime lenses and restricted software support (LR2 conversion was horrible) plus slow autofocus have been frustrating at times. But now the pieces have fallen into their places. Olympus E-P3 with high quality, fast prime lenses fills my needs, finally. Now, after a month´s usage I have really grown together with E-P3 and it is now configured just the way I want. E-P3 is the ultimate ETTR (expose to the right) machine. With it and in body stabilisation I can shoot perfectly exposed, sharp RAW images in most available light conditions. Lightroom 3.5 seems to do a very good RAW conversion from E-P3 files.

I have other lenses and equipment for this system of course, actually a lot - and I have full frame 35mm and medium format digital back systems alsoas well as P&S. But the big ones are for specific planned needs. For those 10% of situations.

Of course I am not claiming that my new rig is perfect and final. It never has been. I am happy to get all the improvements that future will bring. But I could just as well keep shooting with this body, viewfinder and those three lenses if this was the final level of optics and engineering.

-p-

A full frame 35mm DSLR is an overkill in size and weight unless there is a specific use where it gives noticeably better final in-use image quality or other benefits compared to E-P3. These uses seem to arise less and less. My two D3xes live mostly a very relaxed life. In contrast my 5D2s with lots of lenses do mostly music videos - by my son. 

I have always used black cameras since metal OM-1s. For a change I wanted to go back to that style. They only call these silver now...