Perfectly Imperfect. I recently acquired a Russian Helio 44-2 58 mm fully manual lens. Almost legendary for their imperfection to render swirly bokeh, these lenses retain some sharpness at the center, when they are used wide open (f2). To fit my Nikon, I had to use an infinity focus corrected adapter that also contributes to softening the image. I like the lens very much and hope to continue using it.