Is the voigtl nder ultron 40mm f 2 aspherical sl iis sharp wide open?

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From Voigtländer Ultron 40mm f/2 Aspherical SL IIs: Voigtländer Ultron 40mm f/2 Aspherical SL IIs: A prime lens by Voigtländer for Full frame cameras, 40mm f/2. Specs - Maker: Voigtländer - Focal length: 40mm (prime) - Maximum aperture: f/2 - Made for: Full frame sensors - Mounts: Nikon F - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Nikon F): as marked, 40mm. - On APS-C (Nikon F): like 60mm on full frame; f/2 gives about the depth ...

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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