Does the Sigma 50mm f/1.4 ART maintain its bokeh quality at f/4

1. Wide Open Performance: At its maximum aperture of f/1.4, the Sigma 50mm f/1.4 ART produces exceptionally smooth and creamy bokeh. The out-of-focus areas are rendered beautifully, with soft, edgeless bokeh balls in the center of the frame and slight cat-eye shapes towards the edges[1].

2. Stopped Down to f/2.0: When stopped down to f/2.0, the lens still maintains good bokeh quality, but the highlights become slightly more defined compared to wide open. The transition from smooth to more defined bokeh starts around this aperture[5].

3. Stopped Down to f/4.0: As the lens is stopped down further to f/4.0, the bokeh quality changes more noticeably. The depth of field increases, resulting in less background blur. The bokeh balls become smaller and more defined, and the shape of the bokeh highlights may start to show the influence of the 9-blade diaphragm, potentially appearing more polygonal rather than perfectly round[5].

4. Comparison with Other Lenses: Compared to lenses like the Nikon 50mm f/1.4G, the Sigma 50mm f/1.4 ART generally performs better in terms of bokeh when wide open. However, as it is stopped down, the Nikon lens is noted to produce more pleasant and less defined bokeh highlights beyond f/2.0[5].

Summary

In conclusion, the Sigma 50mm f/1.4 ART offers excellent bokeh quality, especially at wider apertures. When stopped down to f/4.0, the bokeh remains good but becomes more defined and less creamy.