Is the nikon z 135mm f 1 8 s plena sharp wide open?

Here is what the site says about that.

From Nikon Z 135mm f/1.8 S Plena: Nikon Z 135mm f/1.8 S Plena: A prime lens by Nikon for Full frame cameras, 135mm f/1.8. Specs - Maker: Nikon - Focal length: 135mm (prime) - Maximum aperture: f/1.8 - Made for: Full frame sensors - Mounts: Nikon Z - Stabilised: no - Autofocus: yes What it frames like - On full frame (Nikon Z): as marked, 135mm. - On APS-C (Nikon Z): like 202mm on full frame; f/1.8 gives about the depth of field ...

From Lenses: Aperture: The f-number says how wide the lens opens. Smaller numbers let in more light: f/1.8 lets in about ten times as much light as f/5.6, more than three stops. A wide aperture means faster shutter speeds in dim light and more background blur. Zooms with a constant aperture, like a 24-70mm f/2.8, keep the same exposure throughout the zoom range; cheaper zooms get darker as you zoom in.

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