Nowadays it is relatively easy to study and compare lenses as manufacturers are increasingly offering technical details of their products. Also, many online review-sites do a wonderful job for photographers by testing lenses. For many photographers this provides a wealth of knowledge that can save a lot of time when searching for an appropriate lens. Color rendition, micro contrast and bokeh are important selection criteria to consider.
When searching for a lens with discernible characteristics
MTF-diagrams and lab-tests reveal only a part of the story. Some aspects of the lens characteristics are, not only technically non-measurable, but also challenging to quantifiable because they are a matter of taste and aesthetics. Especially questions regarding lens rendition gained a great interest in many photographic communities lately. Many photographers want to find lenses that are, not just technically good, but also support their vision. With diverse terms circulating in many discussions, some of them originating from optical theory and others from the realms of art and history, community and brand-centric terms included, it is sometimes difficult to make sense of the big picture.
Technology and aesthetics
If you ask ZEISS product manager Dr. Michael Pollmann how aesthetics goals (aside from technical image quality) are achieved in lens design, he will likely tell you that there are several aspects impacting a lens’s characteristics.
“Lenses – partially it’s a design philosophy, partially it’s the optical concept, partially it’s evolving out of the optimization, partially it’s the used technologies and materials. The ZEISS philosophy is to give the photographer the best possible image to begin with, in order to give him also the widest possible freedom to apply his own creativity”
Dr. Michael Pollmann (Product Manager)
What is “the highest possible image quality”?
Is it, for example, the ability to resolve highest possible resolution without aberrations? “Is it sharp?” or “How sharp it is?” are perhaps the most common questions among photographers when they talk about lenses. sharpness is an important attribute to any lens, and well connected with expectations of high image quality. For ZEISS the image quality does not just refer to technical aspects of the lens but also aesthetic decisions that builds the character of the lens. For many photographers “the look” is vital part of the overall image quality. It is something they see and perceive when working with ZEISS lenses.
The ZEISS Pop
While sharpness is a prevalent and legimate concept in optics, the ZEISS pop refers more to discernible difference in contrast and colors. “An excellent contrast is definitely something we aim at ZEISS. It is a fundamental aspect of optical performance and therefore an important design target”, adds Dr. Pollmann.
It is often the great contrast and colors which evokes initial positive reactions when one tries their first ZEISS lens. In other words, the ZEISS Pop is not concept of optical theory, but a judgment of taste and sentiment, build up by ZEISS user communities, and connected to the way ZEISS lenses render contrast and colors.
High contrast makes images look alive and real
Photographers often describe contrast with nuanced terms like ‘snap’, ‘bite’, ‘punch’ or ‘pop’, all meaning that there is a great separation of different tones in the picture with clear blacks and whites. When a lens delivers compromised contrast the blacks and whites becomes slightly gray and the separation of different tones is also likely to suffer; lesser contrast looks like there is a subtle gray haze in front of the image and it takes a bit of experience to recognize it from images. Contrast can, of course, be greatly altered in most photo editing programs, and while most images benefit from small adjustments, it is important to understand that you cannot restore original contrast.
Life-like rendering of a subject
To gain better understanding of this concept it is important to understand that specific terms like ‘ZEISS pop’ or ‘ZEISS 3D rendering’ do not originate from optical theory of science and they don’t directly refer to technical characteristics of a lens. Rather than approaching these terms from a technical point of view (or as an attribute of a lens), it is more useful to see them as general terms describing a certain perception which manifests itself in images. To be precise, with the term ‘ZEISS pop’ many users describe a life-like rendering of image where the subject seems to ‘pop out’ of the image with a very vivid and striking way. Some describe this perception in their images as ‘3D pop’, and while the effect is quite subjective, it often depends also on many different factors like the use of light in the image, distance between subject and background, and of course, the lens rendition as well.
The effect of micro contrast
Looking it from the science’s point of view ‘the ZEISS pop’ is based on high optical performance which helps achieving this particular effect – especially the high micro contrast which increases a sense definition, sharpness and clarity of an image. Therefore lenses with high micro contrast and acutance are often regarded with a discernible character because they are able to produce images with good definition and excellent contour rendition. To understand the effect of micro contrast better one should definitely study an excellent article ‘Micro Contrast and the ZEISS Pop‘ by renown photographer Lloyd Chambers. He explains how micro contrast contributes to perceived sharpness and ‘pop effect’. While Chambers demonstrates the effect of micro contrast with ZEISS Otus lenses, the ZEISS pop is experienced with other ZEISS lenses as well. For many ZEISS users the ZEISS pop, backed up by high micro contrast and excellent technical performance, is something unique for ZEISS which they find lacking from other manufacturers. “We are of course very grateful, and humble, to see the company name associated so strongly with something that many photographers hold high value in their art. For us, it speaks of company’s success in optical design and meticulous eye for subtle details.” adds Dr. Michael Pollmann.
Difference in the way lenses render contrast
So, with the authority of optical theory it can be said that more contrast is always a preferred choice as it retains the natural elements and subtle nuances of the scene better. However, this position can still be followed by aesthetic question; for example, is there a difference in the way lenses render contrast? It turns out that there actually exist many differences which can lead to different rendition characteristics, as well as varied aesthetic preferences. For example, lenses that are generally considered to be sharp (ie. have a good resolution) might still not deliver good contrast at the same time (ie. lacks acutance).
‘Vivid’ and ‘punchy’ colors
Together with contrast, color rendition marks an important characteristic of a lens. ‘Vivid’ and ‘punchy’ colors are considered favorable attributes. But unlike contrast, colors also evoke emotions and conduct a sense of atmosphere in photography. Therefore the use of colors in photography is very much a question of aesthetics and taste.
Neutral color rendition provides creative freedom
Photographers often describe their lenses having either ‘warm’ or ‘cold’ colors. Lens color rendering is dependent on coatings and glass. They can both cause subtle tints and hue shifts. It is common that color varies, not only among lenses from different manufacturers, but also within different lenses from same manufacturer. Further differences in color rendering are influenced by the camera and its internal color processing, together with user configurable settings. In practice, accurate colors means that when you have set your cameras white balance to 6300K with the 6300K studio lights, you get accurate whites and not slightly warmer or colder image. The accuracy of color rendering becomes even more important when you realize that tints and hue shifts can occur different directions for highlights and shadows, which makes them a lot harder to correct completely.
When colors are accurate and clean there’s a certain sense of brilliance in the image which includes a good color tone separation with subtle nuances; things that are very familiar to us, like human skin, blue sky or green foliage, looks clean and natural without color casts. Accuracy of color rendering and its science marks an important corner stone from aesthetic point of view as well because it provides a neutral starting point for creative process. This is why color rendition of all ZEISS lenses is within very tight tolerances across all lens lines. This means that with color-matched lenses it is possible, not only to achieve great colors, but also to maintain uniform color look when changing focal lengths.
The diverse bokeh
For many photographers the bokeh and other out-of-focus characteristics often provide an unique look to a lens. With the right kind of bokeh you can create images with dreamy character. It is also used to isolate subject from its background and to guide viewer’s attention. In many ways bokeh is an important creative tool which you can use to your advantage when pursuing your vision.
Good versus bad bokeh?
When searching for a lens with a right kind of bokeh it is important to understand that you generally should not try to search for the lens ‘which has the best bokeh’, or step into a pitfall of ranking different lenses based on how blurry background can be achieved with them. Bokeh is not just a single dimensional character of the lens – ‘good versus bad bokeh’. Instead it comes with different characteristics, and in the end, it is an aesthetic judgment of a photographer to prefer one kind of bokeh over to another.
The right bokeh to match your style
Still, the lens and its optical design plays a large part in how the out-of-focus areas are rendered; and characteristics of bokeh can be cut up to technical attributes like the shape and structure of the aperture iris, transition between focus and out-of-focus areas, characteristics of the highlight discs, and so on. Many photographers use terms like ‘creamy’ and ‘buttery’ to describe a certain kind of smooth bokeh that they find preferable for their work. For example, many wedding photographers prefer this kind of smooth bokeh with wide-angle lenses like the Milvus 1.4/35, because it has potential to produce a certain kind of timeless look for images they create.
Finding a perfect lens
Finding your perfect lens takes some careful consideration over many attributes where appropriate focal length and maximum aperture are just a tip of an iceberg. This is where various online reviews and lab tests present a great resource for discerning photographers. Nevertheless, you should accept the fact that finding a perfect lens with a discernible character might be a long journey in the path of discovery. Ideally a characterful lens should offer something very tangible which helps you to realize your creative vision. Maybe it’s the uncompromised image quality which helps one to create large scale prints of nightly cityscapes. Maybe it’s the characterful bokeh which fits perfectly for a black and white photojournalism project. Maybe it’s the strong micro contrast which makes landscapes and sceneries pop out of the image. The possibilities are endless, and the more solid one’s vision is the easier it is to find the lens with appropriate characteristics.
Lens design, culture and ZEISS
In the end, designing a lens is a multifaceted process where science meets art. Only the best lenses withstand the test of time and become highly sought after classics for many photographers over the decades. They succeed, not only because they are excellent lenses from technical point of view, but also because photographers are able to rediscover their characteristics over and over again.
“Aesthetics in lens design precede technology and science. Aesthetics comes from the culture and history of photography. In lens design process cultural knowledge complements the scientific knowledge of ‘technically good image quality’, and in its simplicity the modern lens design is a process where advanced technology is used to combine science and art together to achieve better lenses. While this makes it sound a relatively simple process, it is in fact, a complicated process.” explains Dr. Pollmann.