Pixiq

Good photographic technique is just as important with a digital camera as with a film camera. The digital M is no different in this respect, and just like the M7 and the MP, it demands good photographic skills and knowledge to get the very best from it. These skills and knowledge also need to include a reasonable understanding of what the digital controls can do to help you get the high-quality images for which the M cameras are so well known.

The basic requirements are very straightforward. Technically, what you want from a camera are sharp, accurately focused, and correctly exposed images. It sounds simple and many modern auto-everything cameras do a good job in these departments. But the M will do more than a good job; it will do an outstanding job. However, it does require input from the user. Not only does this input enable higher technical quality to be achieved but also the control that the photographer imposes provides the opportunity for a creative element that combines the aesthetic with the technical.

Focusing

There is no autofocus option with the Leica M8 models, but for the range of lenses up to 90mm, the camera rangefinder provides a super-accurate method of placing the point of focus exactly where it needs to be. With wide-angle lenses in particular, there is nothing to compare with a Leica M simply because the rangefinder system is just as precise with a 16mm lens as it is with a 90mm lens.

It is important to ensure that the rangefinder image can be seen clearly. The range/viewfinder virtual distance is set at 0.5 diopter, so if you need spectacles for this distance, you will need to wear them or fit a correction lens to the viewfinder. Leica can supply screw-in correction lenses, so if your normal prescription calls for +1 diopter, you will need to order a +1.5 correction lens. Although it is not possible with spectacles to see the whole of the viewfinder comfortably, I still prefer to wear mine because I need them anyway to see the shutter speed dial and the image and menu information on the rear viewing screen clearly.

For critical focusing and a more easily framed image with the longer focal length lenses, the 1.25x or 1.4x viewfinder magnifier is helpful, especially when working at the closest distances with the Macro-Elmar, and even more so with the Macro-adapter. Depth of field is minimal at this range and the focus needs to be placed in the optimum position to maximize what little is available. The same is also true when working with fast lenses at their widest apertures. Remember, however, that with the magnifier fitted, you cannot see the brightline frames for anything other than the 75 and 90mm lenses.

Depth of Field

Look through the viewfinder of a Leica M camera and everything appears beautifully sharp; do the same with a single lens reflex camera and only a very narrow plane on which the lens is focused looks sharp, especially with longer focal length lenses. Neither view is accurate, certainly not in the case of the M and only so with the SLR if you are taking your picture at the lens’ maximum aperture. With the M, a full understanding of how the focus point together with lens aperture and focal length control the practical zone of sharpness (otherwise known as depth of field) is essential. With an SLR camera, by stopping down the lens, it is possible to preview the depth of field in the viewfinder. Nevertheless, the level of magnification is relatively low and this can make it difficult to relate the apparent sharpness on the focusing screen to what will be actually achieved on an enlarged image. With an M you do not even have this option, but you can check the image on the viewing screen of the digital camera immediately after taking it, and it may be possible to reshoot the subject.

In theory, the only part of a subject that is sharp is the plane on which the lens has been focused. In practice, there is a zone in front of and behind the point of focus that the human eye still accepts as sharp. This is because its ability to distinguish detail is limited. The accepted convention is that the normal viewing distance for a print of around 8.5 x 11 inches (22 x 28 cm) is 10 inches (25 cm). At this distance, the finest point detail that the eye can resolve is generally accepted as being around 0.25 millimeters. Allowing for the degree of enlargement required, this translates to 0.030 millimeters on the sensor. This point size (or circle of confusion, as it is commonly known) is the normal basis for the calculation of depth of field tables and the depth of field scale markings on lenses. It is an arbitrary standard, and for high quality results, many photographers like to work to a more demanding basis. In my own case, I try to use an aperture setting at least one-stop smaller than the tables or depth of field scales suggest. For example, if the scale indicates that f/5.6 will provide adequate depth of field, I will use f/8.

Some lenses, particularly older ones, may appear to have greater depth of field than others. In some cases uncorrected curvature of field may be the reason. For instance, the old Leica 400mm f/6.8 and 560mm f/6.8 Telyt lenses were relatively simple two-element designs that had small degrees of uncorrected curvature of field, which resulted in the plane of focus curving slightly towards the camera at the edges of the image area, causing the plane of apparent focus to appear deeper. With the type of subjects for which these lenses were primarily intended—wildlife, sports, and journalism— this was hardly ever a problem, and sometimes could even be an advantage. Conversely, the extreme sharpness of modern Leica lenses in the focused plane compared with other parts of the image can emphasize the difference in sharpness between the plane of focus and other areas, and may appear to diminish the nominal depth of field.

Depth of field is dependent on image size, which in turn is dependent on the distance of the subject from the camera. Thus, a subject photographed with a 28mm lens from the same camera position as a 90mm lens and with the same aperture setting will show much greater depth of field simply because the subject is so much smaller. However, if part of the image from the 28mm lens is enlarged to the same size as that from the 90mm, the depth of field will be the same, although due to the degree of enlargement and consequent loss of resolution, the overall quality will of course be reduced. Moving in closer with the 28mm lens so that the size of the main subject is the same will result, in theory, in the same depth of field. The theory works in the close range but at greater distances, you effectively gain more depth of field with the wide angle than the telephoto. Although the main subject is the same size, the perspective change means that the background elements of the image are relatively smaller with the wide angle. A quick check of the depth of field scales on the two lenses or Leica’s official depth of field tables for each lens (http://us.leica-camera.com/photography/m_system/lenses/) will confirm how this works. This information can help you more precisely control how sharp the background appears in relation to the main subject by choosing the right lens for the job.

Hyperfocal Distance

The hyperfocal distance is the lens focus setting, which gives the maximum depth of field for a given aperture setting. This assumes that the farthest distance to be included is infinity. It sounds very complicated but it’s actually quite simple—at least if the lens has a depth of field scale. Instead of focusing the lens at infinity, all you do is set the infinity mark on the focusing scale against the marking on the depth of field scale for the aperture that you are using. This maximizes the depth of field available when the subject has to include elements in the far distance as well those closer to the camera position.

This procedure has particular advantages when working with wide-angle lenses. With the M8, it is necessary to use a separate viewfinder with lenses wider than 24mm and when working quickly, in street photography for instance, it is easy to forget to set the rangefinder focus in the main viewfinder. For many subjects at normal distances, presetting these wide-angle lenses to the hyperfocal distance can save time and avoid focusing errors in these situations. As an example, the 21mm on the M with infinity set at the f/5.6 mark provides depth of field from around 4.6 feet (1.4 m) to infinity. In practice, I would set the aperture to f/8 in order to work to a one stop tighter sharpness tolerance than the standard scales allow.

Always remember that depth of field indications and the related hyperfocal distance settings rely on an arbitrary standard of perceived sharpness in the image. In effect, they rely on what is considered to be an acceptable degree of unsharpness. Only the actual plane of focus is truly sharp and delivering the lens’ best performance. Truly critical requirements (Leica quality!) will always need an aperture setting one or two stops smaller than tables or lens markings may suggest.

Part 2 of this article can be found here.