Originally posted by tromboads you are using a f1.7 with the 28mm step down ring??
Yes. See photo on page 1 of this thread.
Originally posted by tromboads Are you finding a dramatic clarity difference with your f1.7 lens?
No. I have not done detailed side-to-side comparison. But that doesn't mean there is no difference.
I'm sure the step-down ring helps; at least it prevents strayed fingers and the likes from touching the front element of the lens. The step-down ring does not take up any space. Unless I need to use filter, I don't even notice the step-down ring is there.
I just did the exposure test again: with the camera in Av mode, metering off a uniformly-lit scene, the shutter speeds were the same, with or without the step-down ring. If the step-down ring acted as the aperture, my camera didn't notice. That's good enough for me.