Forum: General Photography
06-17-2015, 03:44 AM
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You get prime lenses for a number of reasons -- fast aperture being only one of them. Small size, resistance to flare, and lack of distortion are others that are present in the DA 15 and many other primes, particularly those with a slower aperture. As you say, the DA 15 is consider a landscape lens and works best if shot from a tripod. Is that doesn't work with a particular photographer's style of shooting, than there are other wide and faster lenses out there, although none of them have the same flare resistance of the 15.
To the OP's question, most lenses are sharpest stopped down a stop or so. A lens like the DA *55 or the FA 77 are therefore really sharp at f2 and f2.8 -- places where slower lenses may not even have an aperture setting. It is possible to design a lens that is "sharp wide open," but few companies engineer their lenses that much.
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