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.

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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...

Leica lenses on Olympus PEN

Leica Cruise gave me an opportunity to test some Leica-M Lenses I had not tried before. These were Summilux-M 21mm f/1.4 Asph, Summarit-M 90mm f/2.5 and Apo-Telyt-M 135mm f/3.4 Asph. I shot some images with both M9 and Olympus E-P2.

Some observations

All these lenses are superbly made. Both focusing and aperture rings move firmly but smoothly and aperture clicks are easy to count and set. Intermediate values can be used. These lenses are smallish but heavier than many others because they have no cheap lightweight materials.

On Leica M9 21mm Summilux lens protrudes a long way into viewfinder image and makes composing less than intuitive.  At least I needed to turn the camera all the time to the right to check where lower right hand corner might be and which objects fall into picture and which ones are cut out. Focusing is superbly easy. With 21mm lens you need lots of practise to learn to ”see” compostion already before you look into M9 viewfinder. As you can see from image above, 90mm Summarit is small and compact with M9. Also viewfinder image is still usable. But with 135mm Telyt viewfinder crop is way too small for me. If you are fancying a Leica M9, it should not be because of any subjects needing a 135mm focal length.

On Olympus E-P2 I had a Novoflex Leica-M to MFT adapter. With it I can use any Leica-M lens. Because of E-P2´s smaller sensor, focal lengths are effectively doubled. So, 21mm on E-P2 corresponds to a 42mm lens on M9 (or any FF DSLR), 90mm corresponds to 180mm and 135mm to 270mm. With E-P2 there are no viewfinder worries because electronic viewfinder VF-2 gives an unobstructed 100% view with every lens. I used aperture priority mode all the time with these lenses and manual focusing is quite easy with Summilux and Apo-Telyt. Summarit 90mm does not give an equally contrasty viewfinder image wide open and I had some problems with focusing correctly. One of E-P2 benefits with Leica-M lenses is that you see the real depth of field all the time. The other benefit is ease of setting correct exposure because you can see also that all the time.

Image quality

To put it shortly, 135mm Apo-Telyt on M9 is an outstanding lens in this respect. Summarit is softer wide open but gets it´s act together from f/4 on. Summilux is very good except for corners. This I must say is kind of relative because M9´s resolution is so brilliant. You can see the difference between center and corners easier than with AA-filtered DSLRs. Even offset microlenses can´t fully compensate here for oblique light. Also a super wide-angle lens like 21mm tends to give images that have lots of small details. There was some moiré, which I find correctable in post processing.

On E-P2 Summilux 21mm becomes a mediocre 42mm lens. It proves again the maxim: 35mm is the widest M-lens you can use on MFT cameras. Their sensors are not designed for these lenses. Center is good but corners suffer big time. Summarit 90mm is on the soft side on MFT cameras. If it is not a top notch lens wide open on M9, it becomes an awkward lens on MFT. I had focusing problems because of soft image (2x crop!), and larger apertures give you all kinds of halos and high light fringing on E-P2. Halos can be even nice for some subjects, fringing... NOT. Which leaves us Apo-Telyt. It was a total enjoyment. A very, very handy 270mm (corresponding to FF) f/3.4 lens. Great quality in pictures, I simply loved using it. Too bad there was so little time.  

-p-  

E-P2 / Apo-Telyt-M 135mm. Rocking and moving platform and subject. Still quite nice sharpness. Crop is 100%.

E-P2 / Summarit-M 90mm. Halos can be beautiful. Crop is 100%.

Leica M9 / Summilux-M 21mm. Nice panoramic effect but slight softness creeps into edges and some moiré. Crop is 100%.

Olympus E-P2 plus VF-2

Here they are, the Olympus Twins. Without lenses and detachable viewfinders (and the shiny new black finish, of course) the new E-P2 would be hard to tell apart from it´s brother, the E-P1.

EP-2 has some refinements over EP-1 but the biggest new thing is it´s electronic viewfinder VF-2. E-P2 has a slightly higher hot shoe and a new accessory connector behind it. VF-2 is simply slid into hot shoe and new connector. Push the VF selector switch under the eyepiece and you have a whole new way to look at the world with a PEN. 

I had a pre production EP-2 (firmware 0.9) for a few days and was able to try it and VF-2 in practise. My E-P1 has seen quite a lot of use since late June. Sadly the new EVF is not compatible with E-P1. As a body E-P2 is operated exactly in same fashion as it´s predecessor. So, It felt like a brother should and took just  a couple of minutes to configure menus and map buttons to suit my way of shooting. The only change I made later was to map Fn button for depth-of-field check. This feature is just one of the benefits of EVF over E-P1´s plain brightline optical VF.

Viewfinder VF-2

People at Olympus did not confirm this but obviously VF-2 has Epson´s new TFT panel. Anyway, it has 1.44 megapixels, it´s big and it´s bright. I compared VF-2 to Canon´s EOS 5D MkII and Nikon D3x. Not fair of course, but this new EVF really has a big image. With my glasses I can see the whole image and it´s, well, big. In bright daylight it is no match to these full format 35mm viewfinders. They are smooth, continuous tone, true color; VF-2 on the other hand is still artificial, has paler colors and shows it´s pixel nature in comparison. But when you come to a dimly lit or even an average room the relation changes. VF-2 is brighter and nicer. And when you go somewhere really dark you can´t actually see anything through these fancy optical viewfinders - and 5D MkII stops focusing at all. VF-2 on the other hand turns quite grainy but I can still compose, and the E-P2 focuses at a press of a button just fine.

I had used Lumix 20mm/1.7 lens plus optical VF-1 combination for so long that it was kind of a shock to shoot the first shot through VF-2. It went black for a second... Well, that´s because of a mechanical shutter. When you shoot in continuos mode there is no blackout between shots. After half a day I actually kind of forgot about EVF, it was so nice to work with because you can evaluate very quickly exposure and DOF when you get used to it. It´s a keeper for me.

But isn´t it kind of a funny looking gadget on EP-2! If E-P1 with VF-1 has actually a stylish retro look, then this is what - huh, commie retro style? I can´t help comparing it to a DDR-era Pentacon Six and it´s Soviet Kiev 6 or 60 descendants or what about a brand new (still being made in Ukraine) Arax/Kiev 88 with TTL prism! Oh brothers, Olympus!

The considerable height of VF-2 comes from several issues: add-on construction, articulated construction where eyepiece can be tilted up stepless up to 90 degrees, big screen, high quality no-distortion eyepiece with diopter correction, and finally the hot shoe of E-P2 is higher because of the needed extra connector. Actually the height from base plate to eyepiece is practically the same as with EOS 5D MkII. In practise I did not feel that VF-2 compromised E-P2´s compactness in any way. Which was emphasised by the fact that I had to keep the camera´s identity and design un-noticed all the time. Olympus did here the right thing and did not make a small but crappy EVF like Panasonic for GF-1. What I was missing was some kind of locking for VF-2 to secure it better, now it is possible knock it off the hot shoe.

VF-2 shows of course all the same information as camera´s back LCD. With E-P2 there´s a lot to choose with new finer grids, level indicators, live histograms, exposure information etc - or just a clean, unobstructed view. VF-2 can be also used for  play back and you can switch between VF-2 and LCD at any time. VF-2 is simply the best electronic viewfinder for still cameras I have ever seen. 

 

Other new features

The new connector behind hot shoe can also be used for other accessories, like stereo microphone adapter (EMA-1) and stereo microphone (ME-51S). This adapter slids also into hot shoe - but only one accessory fits in at a time, same goeswith external flash. This has not bothered me so far but I can understand those who disagree.

AF-follow lock is better than with E-P1 according to specs but I did not notice any great difference. At least it´s still not in the league of EOS 5D MkII which is kind of low level for usability for me. 

HD-video is still 720p but now also manual controls work. There are two new art filters: Diorama and Cross Process. Diorama makes people and buildings toylike by blurring up and down and Cross Process gives you fancy color effects. I´m not thrilled, although I actually have used E-P1´s ART 6 for a jerky video project. Last and least there is some more image automatics (i-Enhance) and play back control option via HDMI.

One accessory I would really like to see is an extension cord between body and VF-2. It would give many new possibilities for remote control.

All in all, for me E-P2 is the very same camera as E-P1, just a connector for VF-2. Otherwise same hardware with mentioned accessory and software updates. I´m lucky Olympus brought E-P1 like it did because I have had fun and shot so much with it. Too  bad Epson product development was half a year late for E-P1. Speaking of product development, I feel that Olympus and Panasonic are fighting too much against each other and not together for micro 4/3 system. One more stupid decision is that EVF connectors for Olympus and Panasonic are different!

Availability and price

E-P2 is still being readied for full scale production. Although this pre production sample felt already well finished and I didn´t find any problems with EVF operation, which is the new part of package. EP-2 with VF-2 will be available during January 2010. Olympus is still struggling with E-P1 back orders which they can´t make fast enough. Lets see how they manage then with E-P2. Price for body with  VF-2 is given at 899 euros, which is not bad and in reality shops will sell under that anyway. 

New Lenses 2010

I wished Olympus would introduce fast wide angle and tele primes. In reality those are marginal wishes and Olympus is introducing two consumer series zoom lenses. They are 9-18mm/4.0-5.6 and 14-150mm/4.0-5.6, really compact zooms with ED glass, and available during the first part of 2010. With EP-2´s good stabilizer they are more usable than numbers say, but still...

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Image quality that can be brought out when working with E-P2 (or similarly E-P1) RAW files is outright outstanding when compared to it´s 12MP image size, small physical size and carry around ability. Even so when conditions are far from optimal. The image above is shot hand held with Lumix 20mm/1,7 lens @ 1/40s, f/2.0 and ISO 1000. Doesn´t that tell how dim it was! Images on this page are tweaked my style and don´t represent camera´s quality as such. I´m a photographer not a copy machine... ;-)  This crop is 100%. I did not produce any comparison pair but feel free to compare with your rainy night ISO 1000, f2.0 shots.