Olympus 12-40 easily beats the Canon 17-55 at f/2.8 (but not when stopped down).

Started Nov 3, 2013 | Discussions thread
Guy Parsons
Guy Parsons Forum Pro • Posts: 30,569
Re that DC lens

Sergey_Green wrote:

And you still did not answer my earlier post, as why Nikon added DC to already fast prime lenses. It certainly did not help sharpness, could there be some other motivations in it? Or do you say this lens just does not perform well, plain and simple ?

Having used a borrowed DC lens (the 105mm model) a long time ago in film days, the DC feature was purely to modify the spherical aberration correction of the lens. The degree of spherical aberration control determines the quality of the bokeh behind/before the subject.

Over correct (generally appears to make the focused subject sharper) and the background bokeh becomes harsh and the foreground soft, under correct (softer focus) and the foreground bokeh is harsh and the background soft.

By twiddling the control I could vary the bokeh quality as desired back and front and also sort of reach a compromise where both were sort of acceptable.

Twiddle the control ring past the recommended marks (for the aperture) and the rather expensive lens behaved like a Coke bottle lens. The DC ring needed to be used with care.

Interesting lens but I passed on buying one.

Regards...... Guy

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