pixel questions

The actual resolution of an imager (image chip) is most often measured in linepairs. This is the logical thing to do as the MTF Graphs that are published (in calculated and measured format) relate contrast to the number of linepairs over the image area. Common knowledge assumed that two pixels are enough to record one linepair (one black and one white pixel). A Leica imager in the M line would have approximately 4000 pixels in the vertical direction of 24 mm height. The theoretical resolution would be 83 lp/mm (1/24/2000). Now the classical studies by Zeiss among others claim that the sensible limit (for silver-halide emulsions and 35 mm film size) is 40 lp/mm. The Leica sensor would be able to double this number and resolve more than 80 lp/mm at the limit. My own comparisons with film and imagers indicate that both perform in the same league (when one compensates for the much higher ISO values of the imager compared to film emulsions). It is not the case that the limiting resolution of 40 lp/mm implies that the optical system is not able to resolve more lp. It is the case however that at this value of lp/mm the contrast drops to a low value of contrast and the fine details cannot be distinguished from each other. A study by Zeiss in 2013 shows that one needs at least four pixels to resolve two linepairs. The Nyquist rule explains why: one needs to double the sampling rate to get a clean record of the frequency. So if the frequency is two lp, one needs a sampling rate of 4 pixels to get a clean record of the signal.
If this is true, then we can say that the current Leica M imagers are capable of resolving just 40 lp/mm. The current Leica lenses are capable of resolving 80 lp/mm with sufficient contrast and are clearly overkill for the actual imagers (but they reduce the moire effects).
A possible future increase of the amount of pixels to let us say 36 million pixels would give 5000 pixels per image height of 24mm and a resolution of 1/24/5000/4) or 50 lp/mm. A hardly impressive increase in performance.

Why do we take photographs with a Leica

The species of the dinosaurs became extinct about 61 million years ago in a sudden stop and not slowly dying off. There is still much mystery round the cause and the period of disappearance. Something comparable happened to the species of the Leica photography of the 20th C. This is the style of photography that can be described as the ‘snapshot aesthetic’ (1970) and the ‘decisive moment’ (1950). It was also the period that the world of photography was divided by the amateur snapshot and the art photography. This discussion concerned the content and style of a photograph. The technical discussion of the photographic endeavour focused on the characteristics of the precision manufactured 35 mm camera and the specifications of the emulsions and their developers. The Leica rangefinder camera played an important part as a reference and a yardstick to which other manufactures were compared.
The disappearance of this special world of photography can be traced very easily to the emergence and rapid adoption of the digital image technology since 2000. When the Leica company introduced the Leica M9 in 2009 the classical style of the 35 mm miniature camera vanished from the scene. Many Leica users switched from a silver-halide-based photography to a silicon-based technology and tried at the same time to preserve the old world by continuing to take pictures as if nothing had changed. This is a kind of nostalgia that is firmly rooted in the picture style of the 1950s.
There is another kind of nostalgia that can be described with the title of a book, published in 2016: The Revenge of Analog. Superficially considered one may conclude that this movement falls into the category of the old crafts school: some (quite successful) photographers return to the early photographic techniques of collodion wet plate processes. It is rather intriguing that some of the most popular contemporary filters on social-picture media belong to this category of this retro-style.
Old crafts have a few characteristics that are lacking in modern technology, dominated by the computer and its algorithms. Using tools, thinking about materiality and the development of skills are all part of that mythical practice that defines artists and craftsmen. Photography in general and Leica photography in particular have since the announcement of the technical process in the early 1840s and the introduction of the Leica I in 1925 heavily relied on the crafts and arts to evolve into what has become known as the ‘witness of our time’.
The vernacular (popular) discussion about the difference between analog and digital focuses on the coding technique for signals in communication systems. This difference is often described as continuous versus discrete. This approach is certainly correct, but does not cover all aspects. The analog mentality, the tendency to see and interpret the world with associations, models, and analogies is different from the digital mentality that interprets the world as a virtual space that can be computed with numbers and can be mastered with calculations. When you know that this beautiful figure can be corrected and changed at will, there is no reason to want to preserve it exactly as it is. The image file is a matrix of calculated numbers and every cell stands for a single pixel that can be addressed and programmed.
A more interesting analysis of the concept of analog refers to the the related idea of proportion. A certain level of light energy reflecting from some material surface area sends a number of photons to a light sensitive device. In the silver-halide technique this stream of photons produces a chemical reaction that is proportional to the level of energy.
In the digital technique the semiconductor architecture transfers this light energy into a voltage level that can be measured and given a discrete numerical value.
The digital technology is without doubt more efficient, easier to use and produces improved imagery. It is also completely integrated in the techniques of signal processing and the current information/communication technologies (ICT). The modern digital camera (the digital Leica M not excluded!) is only one of the many artefacts that together constitute the contemporary infosphere.
Photography as a distinct social and technical process has changed fundamentally since the period when the amateur photographer had a special status and followed an identifiable cultural ritual, aptly described by Calvino in his short story titled “Adventures of a Photographer”. One could even assert that photography as a separate craft with its special techniques, materials, tools and expertise has vanished and has been absorbed into the general information and communication procedures of today. Theorists have given this whole process of technical and cultural change the name of a ‘digital turn’. In addition to this digital turn we can also observe a ‘visual turn’: the fact that our culture has been transformed into a visual environment where the image plays an important part. Most products and events we see are drawn or photographed or computer generated and most knowledge we have is derived from such images. We live in a vision culture and social media are primarily visual media: obvious examples are YouTube and Instagram. Photography as a process has been incorporated into the general ICT environment. Photographs as products of this process are integrated into the visual culture and even cameras as technical artefacts are increasingly incorporated into other devices and are combined with other devices: even the Leica M10 has a WiFi module and the Huawei smart phone presents itself as a camera.
The photographic camera has vanished as a special tool for producing pictures and the photographic process is also in danger of disappearing from the list of visual crafts. As an art form however photography has never been more important. The postmodernist movement in the arts has secured a place for photography as one of many tools that artist have at their disposal. Photography is part of the practices of artists who use performance installations and other activities to produce the message and the format. Most photographers are not and do not aspire to be artists and stay firmly on the amateur path, initiated by Eastman around 1900 and described by Baudelaire already around 1860.
The Leica camera was the first precision manufactured camera, designed for the amateur (the wealthy amateur to be more accurate). The draft of the original Leica I was conceived by Barnack and his team as a compact camera that could be handled almost intuitively. It was called by Leitz an automatic camera. The whole construction was made of metal, the only material at that time that could be manufactured with the required accuracy that was needed for the enlargement of the tiny negatives. Leitz had, as microscope and instrument manufacturer, enough experience with this material.
For a long period, from 1930 to 1990, the Leica rangefinder camera represented the species of the precision miniature camera and became the reference for this type of mechanical camera. In his book “The Nikon System” of 1965, Crawley could note that the Leica camera stood head and shoulders above all others in its engineering. In the 1969 edition this remark has been deleted, probably because by then the Japanese camera manufacturers had closed the gap in engineering quality. With the introduction of the Canon F-1 in 1970, they forged ahead.
Today, this assessment would hardly be different. The modern camera has evolved from a (mechanical) opto-mechanical instrument into a (digital) opto-mechatronic instrument. Many important components are no longer manufactured by the Leica Company itself and are outsourced to other companies or purchased from other companies. There is a change from vertical manufacture to design specifications, as can be seen in the construction of the Leica SL. The rather romantic idea that highly experienced workers manually adjust and assemble the camera with great care is no longer appropriate if it ever was. It is evident that the manufacturing technology, based on CNC machinery has increased the accuracy of components. Computer assisted assembly has replaced the manual adjustments. When Leica discusses the superiority of their manufacturing quality, they most often refer to the optical design and manufacture of optical elements. Optical quality is now influenced by the power of the signal processing algorithms inside the camera and on the computer and no longer the isolated part in the classical imaging chain.
The Leica user in the 21
st C is confronted with a number of choices that was absent in the period of silver-halide films and mechanical cameras. Confronted with the dual tendencies that photography has been integrated into the visual culture and absorbed by the IC technologies and is therefore disappearing as a distinct social and technological process, the main question would be: “why do we photograph?” This question is even more relevant because of the billions of images that are being made every day of everything. The next question would be to ask if we do take pictures why use a Leica camera? And the final question, after having answered both previous questions in the affirmative, would be: “What and how do we photograph?” These questions are not new, but need a new answer.

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From there and back again

14/04/18 15:20

This is the title of a song by the Beach Boys and the subtitle of The Hobbit. It is also a reminder of the trend to the revenge of the analog (the recent book by the journalist Sax). As soon as the dichotomy "analog(ue) - digital” is mentioned you seem to touch a sore point in contemporary photographic community. The person who does not bow to the digital superiority and efficiency is a Luddite, a dinosaur and a nostalgic old fashioned idiot who does not understand the signs of the times. There is no doubt that the digital transformation of many parts of the modern technological spectre and the current society and culture has and will have unforeseen consequences. Never say that something is not possible. Sax in his book refers to a post digital era. It seems not possible, given the rapid and successful pace of the digital transformation. And do not mention this possibility to the Leica management: they will swoon and deny it, because they have set all their cards on the digital photography. There is still a small corner (not visible for visitors) in the factory in Portugal, where the old machinery is working and producing old-fashioned M-cameras (M7,MP, M-A). This is all that is left from the proud Wetzlar days when cartridge loading cameras where the ne plus ultra, the alpha and omega of the goal and raison d’être of the company.
There is currently a feeble new spring of chemical photography (often but erroneously referred to as analogue photography). The advocates of the film photography are enthusiastic, but it should be mentioned that Kodak now produces 1% of what it did in its heyday. The prediction of the disappearance of the film is also a bit overhyped. A new technology may disrupt a previous one, but is hardly ever the cause of its extinction. One point should be made at the start: the digital technology (computer based image and signal processing) is more efficient and more productive than its film cousin and the performance of the calculated image is in most cases better than the chemically processed version. At least it is much easier to produce a good image (defined as a sharp picture with full tonality). The content of the image however has not changed since the days of the Daguerreotype.
I use both technologies and select the one that is best for my purpose. It is as with classical cars: for normal traffic and holidays you are well advised to select a modern car with an efficient engine and lost of electronic assistants that make life on the road when driving much easier and safer (presumably!). When you wish to experience the road and the enthusiasm of driving nothing is better than a classic British two-seat tourer. Motorcyclists would prefer a two-cylinder Norton or BSA.
To experience the ‘good old days’ and the immerse myself in the golden age of the precision engineered mechanical camera I am going to use a 50 year old Leica M3, a 50 year old Weston Master exposure meter, a 50 year old film (the ‘new’ Ferrania P30) and a modern Apo-Summicron-M 50 ASPH FLE and the APO-Summicron-M 90 mm ASPH. The P30 will be developed in Kodak D96 (Also an age old chemical). Remember that the Kodak D76 was announced in 1926 and the Agfa Rodinal was mixed around 1900. It is indeed astonishing that such old technology can challenge, but not surpass the current digital imagery. Speed wise there is no competition. The P30 can be exposed as EI 50 and the same quality is easily attained with an SL at EI 5000.
The picture below shows my nostalgic set: included is a Lamy fountain pen and a Moleskin notebook. There is no EXIF to be assigned to the negatives and a notebook is the inevitable choice. The advantage is that I can also note all things I thought and experienced when taking the picture. The EXIF data do not show the mental musings.


The image files in the camera are processed by unknown algorithms. It teas a long study to explore what is happening and this study extends to the computer programs to. Here we have a real black box when using Photoshop. You know the input and the output, but what exactly is happening inside the program is a guess. There are many receipts in books and on the internet in the style of "Do A and B and C and you get D.” But no-one explains to you: the layer you are applying or the slider you are moving functions as follows: it adds a value of +10 to every pixel with original value below 100, unless there is a neighbouring pixel with a value of 36. Only specialised programs show you the exact values of every pixel in the image file.
Compare this to the negative where every small area can be measured with a microdensitometer and its value determined. Chemical developers are explained in detail in the composition of the chemical elements and the working of every element is described. Analogue is in effect proportional and where the calculations are exact (it is 125 and not 126), the chemical process is proportional (the density increases by 20% when the development time is lengthened by 50%.)
This is the nice thing about the chemical process: with experience you get better and you can predict the effects with confidence. The digital photographer would counter: I am not interested: everything can be changed in a later stage.
The difference is emotional and not technical: the classic car has a manual gear box and you shift up and down while paying attention to the amount of revolutions, the vibrations and the sound. The modern car driver sees a blinking number on his dashboard and shifts because the programmer thinks this is the best way. Experiencing the real thing is no longer possible with a digital camera: the whole process is virtual, efficient but not very inspiring. That may be the reason why users of digital cameras are so focused on technical details and technical functions: this is the only way to experience some reality. The digital process is rather fluid: take a picture or a series of pictures, upload a selected few via wifi to the cloud, apply a handful of filters and distribute the file to a range of social media where it will be commented.
Compare this process with the chemical trajectory: Take a picture, wait a week to develop and study the 36 negatives. To develop you have to put the film in a developing tank, prepare the chemicals and proceed, looking at time, temperature and movement. Then do the same in the darkroom: select a negative, project it in an enlarger, determine time and gradation and so on. What a waste of time would exclaim the digital photographer and see the grain and the dust specks. Nice to experience the real thing, says the film adept. Why not do both when you have the choice. That is why I go for the 50year old procedure.

digital and analogue natives

Today I visited in Amsterdam the exhibition about the Dutch photographer Maria Austria (1915 -1975), one of the most admired female photographers in the Netherlands. She was well-known for her portraits, theatre photography and everyday life in the Netherlands. Her work is also famous for the outstanding black and white quality of her prints. She worked mainly with a Rolleiflex, printed with a Leitx Focamat IIc, the famous one!,on Kodak paper and used a Weston Master V for exact exposure settings. All classic products and now part of history and sometimes nostalgia.
See picture below.


Recent sociological studies assume that the current adult population can be divided in digital natives, analog natives, digital migrants and digital curious. It is evident that these groups are connected to age cohorts. The first group comprises people after 1980, the other groups are people born before 1960, people born between 1960 and 1980 and people aged between 54 and 62. This typology implies that there are countries where different people live and work. The analog and digital divide is well known and the two intermediate groups are persons who migrate from one country to another or who visit, as tourists so to speak, strange countries.
It is evident that most Leica users fall in the groups of analogue natives and the digital migrants and digital curious. As is often the case with migrants, they adopt the culture of the new country. It is also evident that the digital migrants are prone to defend their choices and look at the analogue natives as a dying group.

The current revival of silver-halide emulsions seems to invigorate the analogue natives. It is strange that there is much hype about new or re-introduced emulsions, like Ferrania P30 or Bergger 400. There are no better emulsions than the classical ones, Ilford Delta or FP4+ and Kodak T-Max 400 and T-Max 100. I am now sorting my Kodachrome slides and I must confess that the image quality of these slides is at least the equal of the computational images made with the M10 or Monochrome II.

I am tempted to return to te group of analogue natives after having spent much time as a digital migrant and more recently as a digital curious. For the moment I would prefer to be in both categories (analogue native and digital curious). There is so much to loose when crossing the bridge over the river that divides both countries.

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