Are Z lenses APO lenses?

LarsHP wrote:

as1mov wrote:

Hi,

are the Z lenses APO lenses in Leica's sense?

Thanks.

That depends on the definition, which Leica seems to hide or avoid ... !

What I am saying is that while Leica at one point did say what Jono Slack quotes (after reading the thread I link to below), including that color aberrations in the out of focus areas are eliminated, Leica removed* that description later from their website. That is a statement in itself, I think. The reason, I speculate, is that their "apo" lenses do not live up to that description, maybe with a few exceptions.

I asked about the "apo" designation in the Leica user forum in May 2021, which became quite a long thread:

https://www.l-camera-forum.com/topic/320955-90mm-apo-summicron-m-not-apochromatic

The thread includes several sample images shot with Leica "Apo-Summicron" lenses, showing LoCA (longitudinal chromatic aberrations).

The term apochromatic is a scientific one, which means that three wavelengths are fully corrected at the point of focus. Historically, the term was coined in relation to microscopes, where out of focus areas are of no interest. Lack of apochromatic correction will show up in high contrast scenes, typically as magenta fringing in reflections in metal (even when in focus).

Regarding your reference to Nikon lenses, Nikon (as well as Canon, Sony and Fuji for instance) don't use the "apo" designation. I think the reason for that is that most modern quality lenses qualifies as apochromatic lenses. Even if we think of the "apo" designation as Leica / Jono Slack use it, some of Nikon's lenses would be worthy of such a badge, for instance the F mount AF-S Nikkor 200mm f/2.0 VR / VRII.

I tested several of my Nikon micro lenses by photographing a metal torch (flashlight). The 60mm F2.8 AFS micro lens showed clear colour fringing at high contrast areas and in specular highlights. That is otherwise a fine lens, but not ideal for photographing jewellery. Other micro lenses 105mm F2.8D AF and 60mm F2.8D AF) were as bad. The 105 mm F2.8 MC was essentially perfect, and has smooth bokeh too. It is though expensive.

I suspect few F mount lenses qualified as APO, but I haven’t seen tests.

There is or was a 60mm macro lens for the F moint made by a third party which was apo and which cost a not small fortune.

I think that the Z Nikkor MC 105mm f/2.8 VR S lens is an apo lens in the extended sense of the term, but the Z 85mm f/1.8 S and Z 50mm f/1.8 S aren't, even though they are as well corrected as the Leica M "apo" lenses.

* Except for their Egyptian website, where it is still available for readers: https://leica-camera-eg.com/sl-lenses/