This lens is on par with the comparable Leica 35mm f1.4 FLE lens. I have had both lenses and see no difference in image quality between the two lenses. I will say that the Leica lens focus ring is a bit tighter; The focus ring on this lens is a little lost and tends to have a bit of unwanted movement. Regardless, this lens is top notch and I highly recommend it. As an added bonus, this lens's focus ring is a more traditional way of circular movement compared to a Leica lens, which uses a pull-tab to move the focus ring. I don't like the tab so I sold my 35mm M lens and bought this lens.
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