Rain-X revisited :^)

Discussion in '35mm Cameras' started by Charles Gillen, Jun 22, 2005.

  1. You'll recall the scratched lens was a $20 Takumar-A 28-80 F3.5-4.5 macro
    zoom. Sometime in its life it had been tossed into a kit bag without a
    cap or UV filter, and the front element suffered numerous small, light
    scratches (apparently from sharp metal edges) over half the lens... but
    thankfully not too near the center.

    I first applied a _little_ Rain-X and when dry polished with a damp
    tissue. No visible effect on scratches. Next I _flooded_ the front
    element with Rain-X and and when dry wet-polished again. The lens
    cleaned up fine, with scratches _perhaps_ a tiny bit less obvious now.

    Shooting a test series at 28mm 50mm and 80mm showed a very slight flare
    at F4 (my *ist-DS on manual mode would not show any F/3.5) which could be
    improved to "not bad" with a touch of the unsharp mask.

    The flare vanished at F5.6 and above, while apertures F/8 and F/11 were
    quite sharp enough to rescue the lens from the trash can... since
    currently its the only true macro lens I have.

    I was pleased to find no eueball-measureable barrel distortion at the
    28mm position, even after I drew straight lines on the test image's
    vertical and horizontal elements.

    Conclusion: though I had not tested this lens extensively before Rain-X,
    it did not hurt the lens, and _may_ have helped. The lens did _not_ turn
    into a soft-focus portrait lens, which I was willing to risk.

    Note that the Z-wax suggested as a repair is not claimed by its
    manufacturer to fill lens scratches... it is merely a cleaner and anti-
    fog agent, allegedly containing a water-soluable (!) wax.
     
    Charles Gillen, Jun 22, 2005
    #1
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