Focus
Shot with a Leica M6 and a Carl Zeiss Biogon 2.0/35mm
When I try to make meaningful photographs I want to be able to concentrate on my subject and on the way that I want to capture that subject. I don’t want technical issues to distract me from that process.
I have been working on that for some 40 years now and strange enough I discovered that the more technique was added to a camera design the more complicated it became to use, getting more and more of an obstacle between me and my photograph.
In my world there are two main technical problems to overcome, the exposure of the film or sensor (covered in getting it right the first time) and the focussing distance of the lens used. I will try to discuss this focussing challenge here.
With the term focussing I mean getting your subject ‘in focus’, setting the distance between lens and subject in such a way that the subject’s image appears sharp on the final photograph.
History
Let’s have a look at a small part of professional photography history and specifically the focussing options.
Some historical perspective usually helps to understand today’s choices and options.
Nikon F
When Nikon released the Nikon F in 1959 Single Lens Reflex (SLR) 35mm cameras became usable for a broader group of professional photographers. It was the first reflex camera with a decent reflex view finder and a good mirror mechanism, among other important properties. The F was actually a very good camera. With such a camera the photographer get’s a direct impression about the focussing of the lens, among other important things. One sees immediately if the subject is in focus or not.
Before the Nikon F most serious 35mm photography was created with rangefinder cameras like the Leica or Contax. Not because they where that good but because there was no serious alternative. Focussing with a rangefinder camera requires much more skill and experience then when using a reflex type of comparable quality. Other format camera where used as wel, especially the Twin Lens reflex Rolleiflex.
It is a myth that documentary photographers used Leica ‘because it was the best camera’. The Zeiss Contax was considered to be better and was used by a lot of famous photographers like Robert Capa. Many of his photographs are claimed to be made with a Leica but where actually shot using a Contax or Rolleiflex.
During the Korean war photographers like Douglas Duncan discovered Nikkor lenses while in Japan and fitted these to their German rangefinder cameras. These optics where superior to the German glass and paved the way for an acceptance of Japanese cameras in the west.
With the SLR photographers started to discover the advantages of a reflex camera, especially when using longer lenses then ca. 90mm or short wide angle lenses, which are very difficult to handle when using a rangefinder (see Visoflex for the longer lenses). A lot of the photographs that where fashionable in the ’60s would not have been possible without the reflex type cameras like the Hasselblad and Nikon.
Universal
The SLR cameras like Nikon, Pentax and later Canon etc. became popular because they are very versatile.
They may not be the best choice for some types of photography, especially the documentary type of work, but they are a jack of all trades and that is good enough for most photographers. Hence it’s popularity and the reason why the (D)SLR is by far the most used type today, to such extent that many people don’t even know that other types exist.
For the purpose of discussing viewfinders I include mirrorless cameras as part of the single lens camera type because they use the camera lens to view the subject like an SLR camera.
Viewfinder
An SL(R) camera looks at the subject through a single lens mounted on the camera. Please view this link to understand the principle. A mirrorless camera does not use a mirror (obviously) and is therefore not a reflex but does follow the single lens principle.
Other types of camera are, among others, the single lens View Camera (for example the Cambo or the Sinar), the Twin Lens Reflex or TLR (for example the Rolleiflex) and the Range Finder or RF (like the Leica), although not all these ‘rf’ cameras actually use a rangefinder. They do use a separate viewfinder to see the subject, though.
The viewfinder defines the type of camera, giving us an indication of the importance of how we view the subject in relation to the way we operate the camera.
Advantages of the Single Lens (Reflex) camera
Looking through the same lens for viewing and focussing has some advantages:
Eye parallax
Most importantly, there is no difference in viewing angle. The RF and TLR viewfinders look at the subject at a slightly different angle then the actual lens that will take the picture and that can be a problem, especially when working close to the subject. We call this difference in viewing angle ‘eye parallax’ or simply parallax.
WYSIWYG
Second advantage is that you see exactly the same image as the lens sees, no guessing or having to use separate frames or add-on lenses, think i.e. close up photography. That seems normal now but photographers have been struggling with that for decades and the only real solution before the SLR would be to use a View Camera.
Disadvantages of the SLR
There are also some disadvantages to a single lens viewfinder.
Dark viewfinder with some lenses
If your lens has a small aperture, like a 6.3/400mm, the image in the viewfinder is rather dark, the lens will not allow a lot of light through. The viewfinder will only see the amount of light that the lens can pass through.
Focusing
For the majority of your photographs you use the viewfinder to focus, meaning that you will need a mechanism in the viewfinder, like a focusing screen, to quickly see if the image is in-focus or not. This mechanism can not be optimised for all apertures, focal lengths and lens angles, it will always be a compromise and it can be a challenge to focus 100% accurate, especially in low light.
Time parallax
Using an SLR, after pushing the shutter release the aperture in the lens wil close to the aperture setting that was selected for the picture and the mirror has to move out of the way, or the electronics have to switch between viewfinder and picture taking and set the correct focus distance on the lens in case of some mirrorless cameras.
All this takes time. As a result the image will not be created in the same instance that you push the shutter release.
This time difference can be as big as a few milliseconds, very noticeable when photographing.
We call this ‘time parallax’ or shutter delay and it can be an issue when trying to catch a specific moment in your photograph.
A true range finder camera (or a TLR) does not have this time parallax and is therefore more suited for the type of photography where catching the exact right moment is important. This is one of the reasons why documentary photographers might use both SLR and RF cameras and select the one best suited for the actual photograph they intend to make.
Some mirrorless cameras have a considerable time parallax and are not suited for decisive moment types of photography.
Subject relation
With an SLR or mirrorless camera, only the in-focus part of the image is clearly visible, everything else is more or less out of focus depending on the focal length and aperture of the lens used.
This means that you may have no optimal information about what is happening in the foreground and background.
This can be very important when you want to make a photograph that shows a relation between different objects because you may not see all those objects clearly, if at all. This is where a camera with a separate viewfinder like the range finder type excels and it is an important reason why you would want to use a camera like a Leica today.
Zone focusing
Zone focusing is not very practical with an SLR. We will get back to that very important issue later in this artikel.
Auto focus
As described, exact 100% accurate focusing could be a problem with the classic viewfinders.
The image could be to dark, the focusing mechanism could be difficult to use and this mechanism would be in the centre of the viewed image where the action often takes place, obstructing important subject information. Professional SLR cameras offered different focusing screens to remedy this issue a little.
All this changed with the invention of the auto focus.
History
During the 1970’s era Leitz, now Leica, invented the auto focus technique and in 1976 created a prototype called the Correfot, based on their SLR model.
Being the conventional Leitz of the day they where not convinced that the focusing quality was up to their standards, they sold the idea to their then partner Minolta and the rest is history.
Most photographers today never even used a real manual focus camera. Auto focus rules and is a very useful addition to the arsenal of photographic techniques.
The first systems used only one focusing point at the center of the viewfinder. You would point the focusing point at the subject, focus, maybe re-compose the image and take the photograph. Exactly the same procedure as used with manual focusing, it worked very well and allowed for a lot of control on what would be in-focus.
Even better, there where hardly any disadvantages with the early auto focus cameras. Focusing was fast enough for average use and worked almost 100% accurate, much better then the previous manual focusing using an SLR viewfinder.
My first auto focus camera was the Nikon F4, in my opinion one of the best cameras ever build. I wish they would make an exact replica with a digital sensor, it would be sensational.
Progress
Unfortunately, the Japanese manufacturers could not help themselves and added a lot of options to the auto focus mechanism, spoiling the lot in the process.
Auto focus has become another mechanism that has to be checked and cannot be relied on unconditionally. That is a bad thing.
Reliable focus is a basic requirement for a camera. A lot of added technology is invented and added with every new model, as usual, but that introduces more choices to make and more functions to check and new problems with the new technology that have to be remedied in new versions. I do see a business model here.
It takes a lot of effort to understand and remember all the AF modes and to know what setting to use for what type of photography. And you have to set that mode somehow before making a picture, either using one of the many buttons on the outside of the camera or, even worse, somewhere in a menu.
Somehow very simple things got very complicated and one could ask how that happened. How did yesterdays simple cameras become todays menu driven computers? Even more important, what can we do to get our camera back and make it work for us and not against us?
Simply taking a photograph is not possible anymore, you have to program your camera first.
Photography used to be simple, but it is soiled by todays cameras.
Remedy
What can you do about it?
Get a simple camera
You could forget about all those option packed computerised monsters and get yourself a simple camera with only basic options.
Unfortunately those are not easy to find, the best known is the Leica digital camera. It seems expensive although throughout it’s history a Leitz camera has never been cheap. Price wise it does compare reasonably wel with other high-end cameras from other manufacturers. Only now you have to pay more to have less.
Single focus point
Another possible option could be to forget about all these auto focus modes and only use one focus point in the center of the viewfinder. This is a tried method that has worked for centuries with manual focusing and early auto focusing. It will work fine for almost all subjects, provided that the auto focus module itself is reliable which is not always the case.
Point the focusing spot on the subject that needs to be in-focus > focus > re-compose and shoot. This can work, depending on the ability of the camera to actually focus on the point you directed it to.
Manual focus
Yes, this still works. Not that good with auto focus lenses, very good with lenses and focussing screens designed for manual focus, like the Zeiss ZE and ZF range of reflex camera optics and all pre-AF camera body’s.
For most people it will be a new technique to master, but it works remarkably wel, photographers used nothing else for decades.
Most subjects don’t move. Do you really need auto focus to focus on a landscape or a building?
Even people usually don’t move that much, manual focus might work really good.
Depth of field
The depth of field scale on a 35 mm lens
The aperture is set to f 8. The depth of field shows everything sharp between ± 5 m and infinity
You do know about depth of field, don’t you? If not, you might want to learn about it. All photographs show some depth of field, it is a vital ingredient of a picture.
Use that technique to increase the field of focus. Now you can afford to be a little off focus, it will be absorbed by the depth of field.
Most modern lenses have no depth of field table on the lens barrel, which would be a problem.
Depth of field is essential to photography. A photograph tells a story, objects relate to each other. You should be able to distinguish those objects to understand or guess their relation to each other. Even when the photographer chooses to picture only a single subject the viewer wants to be able to build a relation with that subject. The right amount of depth of field is essential for such an understanding.
Pre focus
Very simple and easy to use.
Imagine a runner on a track. You know that this person will be at a certain spot after a certain amount of time because the track is fixed. Focus on that spot, click when the runner has reached the spot, or just before that moment if you have to consider time parallax. Add a little depth of field for variation in technique, done.
Zone focusing
This is the most important technique of them all, closely related to the depth of field and the pre-focus technique, but unfortunately very difficult to obtain with a camera that views through the lens like a (D)SLR or a mirrorless camera.
In documentary photography a saying goes “f8 and be there”.
This zone focussing technique was used for most of the historic photographs that you know, it was the way to catch a decisive moment because the photographer does not have to spend any time focusing.
All photographs in this article were made using this technique combined with rangefinder focusing. For the top photograph I also used pre focusing.
If your lens does not have a depth of field scale you can not comfortably use zone focusing.
Explained
How does it work?
Use at least a medium wide angle or normal lens, like a 35mm or 50mm or wider on a 24cm x 36cm sensor or film format.
Set your aperture to a value that offers a good depth of field, like f8.
Look at your depth of field scale. If your subject is somewhere between ca. 1.5 and 2.5 meters, almost all generic pictures will be in that range.
Set the distance to ca. 1.6 meter. Now everything between ca. 1.2 and 2.5 meters will be in focus when using a 35mm lens.
No need to focus, just shoot, everything between ca. 1.2 and 2.5 meters is sharp!
That is to say, sharp enough. Depth of field is a relative value and with the current digital ‘perfection’ and high MB sensors ‘sharp’ is a very subjective sensation.
We might ask ourselves why we need this extra definition from these sensors but that is another discussion.
The purpose of photography is to create a photo and to look at that photo. The whole photo. If the objects we want to be sharp appear to be sharp all is wel. No need for a closer look or a detailed observation. If the complete photograph looks good it is good.
Zone focusing works in real life. Set a usable aperture, set the approximate distance to your subject and let the depth of field do the rest.
Your photographs will be sharp. You do not have to use any focusing mechanism. If you combine this zone focusing technique with a pre-set aperture and shutter speed (see getting it right the first time) you wil beat any electronics driven camera in operating speed. Just point, compose and click. The technique is as old as documentary photography.
Digital cameras
With modern digital cameras zone focussing is almost impossible. Most modern lenses have no depth of field scale. But there are ways to work around such problems. Some cameras have a depth of field scale in the viewfinder, if you activate that option. Some cameras have a separate viewfinder. Most cameras have the option to attach older lenses that do have a depth of field scale. Some new lenses do have a depth of field scale.
You can focus manually with most mirrorless cameras. The viewfinder systems are not designed for this manual focussing but it is possible and doable. You can practice manual focussing, as with everything, the more you practice the easier something becomes. Play with your camera, try focussing options, try exposure settings. A digital camera gices you instant feedback if you want, it is a perfect tool for learning.