Emily Therese in Yonkers

Starting with focal length:

A lens with a focal length approximately equal to the diagonal size of the film or sensor format is known as a normal lens; its angle of view is similar to the angle subtended by a large-enough print viewed at a typical viewing distance of the print diagonal, which therefore yields a normal perspective when viewing the print. If the frame size is 24mm x 36mm, the diagonal is 43.267mm.

Most manufacturers market the 50mm lens as the normal lens (despite being a few mm larger) as it is the optimum focal length that has zero distortion. The problem is that a 50mm lens only affords a 46-degree field of view that is significantly less than the human field of vision – which would be closer to a 24mm lens. However, if we were to use such a wide-angle lens our images would suffer significant distortion that does not appear when using a normal lens. Our brains have the ability to compensate for this distortion – however the camera does not. Therefore the 50mm lens is considered to be optimal, due to lack of distortion.

Aperture:

Computing the f-number of the human eye involves computing the physical aperture and focal length of the eye. The pupil can be as large as 6-7mm wide open, which translates into the maximum physical aperture. However, the entrance pupil is typically about 4 mm in diameter, although it can range from 2 mm ( f/ 8.3) in a brightly lit place to 8 mm ( f/ 2.1) in the dark.

There are many 50mm lenses that are f/2.1 or faster. The race for the optimum optic started in Japan in 1953 with the introduction of the Zunow 1.1/50mm lens, followed in 1954 with the Fujinon 1.2/50mm. These lenses were offered in both Canon and Leica screw thread mounts. Comparably, the 1.1 and 1.2 were a significant difference from a previous standad of 1.5. Canon and Nikon responded in 1956 with a 1.2/50mm lens with seven elements (canon) and a 1.1/50mm lens with nine elements (Nikon). Though Nikon and Canon were focusing on SLR development, Canon did introduce the .95/50mm lens for the Canon 7 in 1961.

Canon then introduced a 1.2/58mm lens that utilized aspherical surfaces in 1971. The first series used aspherical surfaces that were grinded by machines that were manually operated. Only later (but long before Leica) did Canon switch to a fully automatic grinding process.

An aspheric lens or asphere is a lens whose surfaces have a profile that is neither a portion of a sphere nor of a circular cylinder. The asphere’s more complex surface profile can reduce or eliminate spherical aberration and also reduce other optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design. Aspheric elements are used in the design of multi-element wide-angle and fast normal lenses to reduce aberrations.

According to Canon’s original advertisement for the .95 lens “holds razor sharpness even at full aperture” In fact the Canon lens wide open is a good practical example of the working of spherical aberration. Spherical aberration is an optical effect in lenses that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike nearer the centre. It signifies a deviation of the device from the norm, and results in an imperfection of the produced image.

Spherical aberration should not be confused with barrel distortion; whereas barrel distortion affects the shape of the image, spherical aberration affects its sharpness.

A high-speed lens with optimum optical sharpness is the desired pinnacle for any camera system. The marketing argument has been focused on the use in low ambient/natural light or even the absence of illumination where the just hand-holdable shutter speed could be the dividing line between a good and a lost picture.

Almost every design relied on spherical lens surfaces and the designer needed additional lens elements and more exotic properties and/or daring shapes to get a decent quality at the widest apertures. The pictures that could be made with these lenses could be described as acceptable only with a benevolent approach. Canon went over the top with its 0.95/50mm lens for its rangefinder camera.

Around 1965, several manufacturers abandoned the rangefinder format, leaving Leitz as the sole survivor. Leitz took this opportunity to produce a lens to rival the Canon .95 lens – the last viable lens of that type on the market.

Their research into the design options indicated that the only solution for a lens that combined a compact mount with good performance was to use aspherical surfaces. The aperture of the original Noctilux was set to f/1.2. A wider aperture required a bigger mount and it might also be assumed that the size of the lens elements was too large for the aspherical grinding process.

The successor of the original Noctilux widened the maximum aperture to f/1 and used only spherical surfaces. The performance wide open was better than what the Canon .95 offered., perhaps due to the new glass types available to the Leica Designers.

The Noctilux 1/50mm stayed in production from 1976 until 2008 when a new version was produced. The designers opted for the .95 aperture – an 11% increase in pupil diameter – providing significant need for chromatic correction. The new Noctilux .95 has a more rigorous correction of aberrations over the entire field. Wide open the differences are less pronounced with the previous version, but interesting enough to analyze. The design of the lens is state of the art with a floating element, aspherical surfaces and a selection of new glass types specifically selected for this design.

Wide open the lens shows a certain softness of major subject outlines. The lower contrast of the high frequencies (fine textural details) softens the edges of the low frequencies (outlines of major subject shapes). Stopping down to 1.2 does improve the overall contrast; even more so at 1.4. Though, contrast is also modified in post processing.

At F/.95, it should be clear that this lens outperforms the human eye in terms of allowing more light to expose our frame. However, the Noctilux is special for two other reasons beyond its speed. The first is its freedom from flare. Even with light shining almost directly into the lens, flare is minimal. Considering the conditions for usage of such a lens – this is a remarkable quality.

Secondly, is the extremely narrow depth of field when shooting wide open. Depth of field is measured in inches – as opposed to feet – and consequently the background will be that much more out of focus. The Noctilux, by design, renders out of focus areas very smoothly, rendering an almost impressionistic quality to those areas.

This impressionistic quality allows the artist to compose the elements of the photograph accordingly. The gaze of the viewer will then tend to linger over these points of interest. Elements are arranged with consideration of several factors (known variously as the principles of organization, principles of art, or principles of design) into a harmonious whole that works together to produce the desired statement — a phenomenon commonly referred to as unity.

Some principles of organization affecting the composition of a picture are:

* Shape and proportion
* Balance among the elements
* Harmony, or consistency among the elements
* The orientation of elements
* The area within the field of view used for the picture (“cropping”)
* The path or direction followed by the viewer’s eye when they observe the image.
* Negative space
* Color
* Contrast: the value, or degree of lightness and darkness, used within the picture.
* Geometry: for example, use of the golden mean
* Rhythm
* Illumination or lighting
* Repetition (Sometimes building into pattern; rhythm also comes into play, as does geometry)
* Perspective
* Breaking the rules can create tension or unease

The position of the viewer can strongly influence the aesthetics of an image, even if the subject is entirely imaginary and viewed “within the mind’s eye”. Not only does it influence the elements within the picture, but it also influences the viewer’s interpretation of the subject.

A subject can be rendered more dramatic when it fills the frame. There exists a tendency to perceive things as larger than they actually are, and filling the frame fulfills this psychological mechanism. This can be used to eliminate distractions from the background.

In photography, bokeh is the blur, or the aesthetic quality of the blur, in out-of-focus areas of an image, or “the way the lens renders out-of-focus points of light.” Differences in lens aberrations and aperture shape cause some lens designs to blur the image in a way that is pleasing to the eye, while others produce blurring that is unpleasant or distracting— “good” or “bad” bokeh, respectively. Bokeh occurs for parts of the scene that lie outside the depth of field. Bokeh is often most visible around small background highlights, such as specular reflections and light sources, which is why it often associated with such areas. However, bokeh is not limited to highlights, as blur occurs in all out-of-focus regions of the image.

Emily Therese in Yonkers