Wednesday, February 1, 2017

The Problem with Modern Lenses - MTF vs Micro-contrast

The Problem with Modern Lenses
MTF vs Micro-contrast

The Problem with Modern Lenses

Thoughts on the Right Camera and Lenses

The Lens Intention Diagram

sigma art 35 mm f/1.4    flat lens   low micro-contrast
sigma art 50 mm f/1.4    flat lens   low micro-contrast

The flattening of modern lenses or the death of 3D pop 

and How a lens works

Glass becoming evil

Glass becoming more evil

What is lost at the end of all this?

How to view and compare depth rendition

7 elements Nikkor AF 50mm 1.4D vs 13 elements (with 3 ED glass and 1 Aspherical ) Sigma ART

On a wide landscape, the distance between foreground and background objects is captured clearly on the depth lens but confused on the flat lens. The depth lens also capture drastically more tonal nuances than the flat one.

The next lenses of the future will be flat lenses for sure

More observations on low-element count lenses.

  • They are older lenses: lenses made for film (people like shooting film because it feels “more real", now you know why lol) with less rounded aperture blades and less recent coating.
  • They don’t perform as good as flat lenses at maximum aperture: One needs to learn how to close the aperture well according to the light. The bokeh won’t be as creamy as a new flat lens.
  • They mostly won’t provide corner to corner sharpness until f11: Downside of less glass correction. Wide angle lenses are the most to suffer low-element count.
  • They are very cheap to buy used most of the time: Most of the world has been sold onto upgrading to a flat lens.
  • The theory mostly applies to prime lenses: I have tried many low-element count zooms and the differences are more subtle.
  • The theory applies to focal lengths above 35mm: there are many compromises made to design lenses of 24 and wider.
  • Ideal low-element count number is below 9
  • Most low-element count lenses aren’t fast lenses
  • They don't have plastic elements: The effect of 1  plastic element (or called "hybrid aspherical") is quite damaging to the depth.
  • The higher the element count, the closer it needs to be used only at max aperture.
  • Not well reviewed: every review site on the internet will shit on them.
  • Darn cheap: The used market is full of them. Chances are the user is selling them for purchasing expensive flat lenses.

More observations on high-element count lenses.

  • They are modern lenses: Made with the latest sauce on “rounded aperture blades” and lens coating mostly for better bokeh and wide open sharpness.
  • Maximum aperture champions: they provide maxed out values of sharpness and bokeh (most of the time).
  • Nightcrawlers: Their high correction gives them amazing flare resistance at night.
  • They can only be used at max aperture: High-element count lenses have “3d pop” only when the background is blurred. When the background is visible, it is flattened on the subject.
  • Easier to use for beginners and casual consumers: They are corrected for any aperture.
  • Well reviewed: huge promotional campaign on the lenses on every lens review site/blog.
  • Heavy: lots of glass in there.
  • More expensive: tons of materials more.

Compromises to be made, to buy both or not?

A high element count lens isn’t necessarily bad and a depth lens isn’t necessarily good. I would buy such a lens for its “bokeh effect” when used on max aperture or its ability to provide sharp corners on extreme occasions of need (a specific landscape picture that needs corner detail) then quickly go back to the depth lens for general purpose. Some people prioritise sharpness more than depth . In my case, I tell stories in my images. The lenses I use must be able to respect the composition I see with my two eyes and depth information is also part of the story. On some occasions, I would require “bokeh quality” to help shape the mood, on most occasions I need context. Photography for me is the reproduction of reality. I lose fidelity by using a higher element count lens.

Youtube Playlist on optics and depth rendition
Quick follow-up lens comparison article on my blog
A video that compares flat and depth lenses (thank you Robiro from dpreview forums)

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).

Otestujte si svůj objektiv – difrakce aneb ohybová vada

sigma art 35 mm flat lense
low-pass filtr
mikro kontrast

1 comment:

  1. Lens Sharpness

    Lens sharpness doesn't mean much to good photographers