Micro-Contrast, the biggest optical luxury of the world
When I started photography, life was simple: get a good camera (a Nikon D80 at the time), get a sharp lens and be happy. As I kept growing, I learned to read lens reviews for my camera in terms of measurable characteristics like MTF resolution charts (for sharpness), distorsion and chromatic aberrations (through photozone.de) in order to purchase the right equipment for my camera. DXOMark made comparisons even easier. Even though my purchases weren’t so expensive, I’ve always felt great reassurances in using sharp lenses that I’ve carefully researched for. Life was simple, going one Nikon camera after another, trying a bunch of photography equipment and comparing them on measurable values again: sharpness, bokeh, ISO and dynamic range. It went on like this for years: Nikon, Canon, Pentax, Olympus, Panasonic, Fuji, Sony, etc… they all seem to be so similar on paper and sharpness. Every article online even went to compare lenses on 1:1 pixel level close up to clearly demonstrate the superiority of a lens over the other. While, I’ve rarely questioned the cost of Nikkor lenses, I’ve always asked myself: Why do Zeiss lenses cost so much? Why do Canon L lenses cost so much? When you start reading about them, some photographers describe something intangible that can’t really be noticed on side-by-side images but in the displayed body of work produced with these lenses, as if the photographed subjects suddenly felt more alive than with “sharper” “more perfect" optics. At first, I thought it was a question of dynamic range but then it wasn’t really it. I didn’t know it was due to micro-contrast then. Now, I shall explain it to you.
IN CLEAR DEFINITION
Micro-contrast is the ability of the lens to communicate the richness and vibrancy of the inter-tonal shifts between the brighter to darker part of a very same color onto the sensor. A lens with great micro-contrast has much richer colours and tone transitions compared to a weaker one. It's one of the attributes that people refer to the 3d-pop. It has absolutely NOTHING to do with resolution (measurable sharpness).
HOW TO SEE IT?
Another blog article will explain how to compare the micro-contrast of lenses. It basically comes down to this.
- Take a well exposed image preferably a landscape.
- You convert the image in black and white
- You pay attention to how the many shades of grey are rendered in the image.
- A lens with great micro-contrast will have more shades and quicker contrast cut-off than a lens with low-micro-contrast.
- When converted back to color, the lens will showcase a large variety of tones of each color.
WHAT CREATES IT?
Micro-contrast is the result of optical design and secret glass manufacturing recipes that lens manufacturers never reveal. The lens then sends the appropriate color and tonal information onto a well made sensor for maximum image rendition. Cheaper third party glass from Sigma do have a tendency of rendering poorer micro-contrast.
While element count influences a lens' depth rendition, micro-contrast is one of the key aspects of a lens’ successful depth perception. A lens with great micro-contrast can communicate multiple tones very well compared to a weaker one from foreground to background. If photography is practiced at an enthusiastic or passionate level, one would want to use such tools to translate their vision without needing to go through some post-processing gymnastics on the computer software.
MICRO-CONTRAST AND ELEMENT COUNT ARE TWO COMPLEMENTARY PROPERTIES
As we have previously learned, low element count improves the transparency of the lens to let in more colour information of the light thus influencing depth rendition. The resulting micro-contrast grades tones in order to improve depth perception.
LET ME REITERATE: IT ISN’T ABOUT SHARPNESS
It is very confusing at this point to compare micro-contrast and sharpness, especially since most of the lens reviews on the internet these days put so much emphasis on sharpness (measurable resolution or MTF). Sharpness is usually perceived based on high global contrast measured at pixel level. Unlike measurable resolution, micro-contrast is perceptible not measurable. A lens with great micro-contrast can produce a photograph that appears to be life-like and tridimensional despite it being unsharp or out of focus. A lens that excels only at sharpness (like Sigma ART, Zeiss OTUS and Milvus, Sony G-Master or Canon non-L lenses) cannot achieve such a feat.
Here's a quick example of sharpness (high res, high MTF) vs. micro-contrast
WHERE TO FIND IT?
Micro-contrast is a premium attribute in some brands while being spread more evenly on others.
- Canon has two line of lenses clearly directed at two drastically different users: L (enthusiast and professional users) and non-L (occasional and casual users). While some non-L or third party lenses might score higher than L lenses on test charts, Canon L lenses are the better Canon lenses with micro-contrast and will have superior rendition to the non-L. The price gap between a Non-L and a L lens is close to double price. Canon is also starting to release replacement version to their original L primes lenses, many of which lose their micro-contrast in favour of resolution.
- Nikkor lenses all have okay to excellent micro-contrast as this attribute is spread more evenly across the entire optical library, but usually cost a little more than Canon’s affordable non-L lenses depending on wether it is from the Ai/Ai-S, AF-D or AF-S line (many AF-S G prime lenses have inferior micro-contrast to their older AF-D line)
- Voigtlander SL lenses have amazing micro-contrast (sometimes at the cost of sharpness) and cost just a little more than Nikkor lenses.
- Many Zeiss ZF/ZE Classic lenses have world leading micro-contrast and are perhaps the most premium lenses for dSLRs. The Zeiss OTUS and Milvus lenses have reduced micro-contrast in favor of resolution.
- Sigma ART lenses do not have micro-contrast at all.
- Sony E-mount lenses lineups are similar to the Canon model. Non-L lenses are replaced by G and non-G lenses. L lenses are replaced by premium Sony lenses with Zeiss design and coating. Lately their goals are to reduce this attribute in favour of resolution in the G-Master lenses.
- Fuji XF lenses all have good to great micro-contrast like Nikkor lenses but they require the use of Iridient Developer (Mac OS only) to reveal their true nature.
- M43 lenses have awful to very good micro-contrast but it is harder to identify which ones since they are still figuring out ways to exploit that attribute at the sensor-level (they might have reached solution in the GX8).
WHAT TO DO NOW?
In this sharpness centric world, lenses with micro-contrast will slowly disappear into the used market as they are slowly being replaced with lenses of resolution only since this is what the uneducated number seeking consumer wants or is being educated on by a system that is comprised of
- Professional photographers (knows photography but are resolution junkies)
- Internet tech reviewers (know how to measure and write but are resolution junkies)
- Camera store salesmen (know how to sell but are resolution junkies)
All of them will push the idea of sharpness (measurable resolution) towards to the consumer as we advance in this interesting period of photography. Spend the money on the right lenses with great micro-contrast to make more realistic images! This attribute is a much better long term investment than ever evolving resolution and is clearly worth investing in.