This ƒ/2.8 - ƒ/16 aperture series was shot to explore the background blur characteristics at 70mm at close range— a tight head and shoulders portrait.
This is the same image used for the correction of color fringing example.
Bokeh is quite pleasing centrally, but becomes less smooth towards the edges and corners. For a portrait, this area would likely be well out of focus, and so that would matter little.
Also of note is a typical off-center effect when wide open in which the edges and corners appear to be somewhat sharper in out of focus areas than more central areas; this is in part due to a smaller effective aperture away from center (optical vignetting). This effect diminishes with stopping down.
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Since 2006, Diglloyd Advanced Photography is the authoritative review and reference for DSLRs and their lenses: Canon and Nikon primarily, but also Pentax and some medium format. Reviews of key DSLRs are included, but the primary focus is on lens performance. Also included is a wealth of technique and workflow approaches.
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