doug_nelson3 Posted December 2, 2011 Share Posted December 2, 2011 <p>Just received a "Mint" DA70 on the auction site. It has an oil slick visible from the rear, on one of the inner elements. Nothing like this visible from the front, outside barrel looks mint. So when I put it on my K-r to take shots of solid-colored surfaces to see if stains show up, it won't focus on the sky; it just slams back and forth like a macro that can't find focus. Anyone see anything like this seen on a DA lens? Am in negotiation with this seller.</p> Link to comment Share on other sites More sharing options...
pj_vesterback Posted December 2, 2011 Share Posted December 2, 2011 <p>What's in the sky to focus on? If it is just a blue sky, it won't be able to focus.</p> Link to comment Share on other sites More sharing options...
doug_nelson3 Posted December 2, 2011 Author Share Posted December 2, 2011 <p>PJ, Yes, I saw that. I set it on manual just to get a shot of a continuous tone to see if the oil slick shows up. It just surprised me when it started slamming back and forth. If that's normal behavior when shooting at clear sky . . . Focus seems normal when taking normal pics, and the lens seems every bit as sharp as it is said to be. The internal oil slick seems a matter of oily aperture blades that got oil on the glass. I've yet to see it in any shots, but it is awfully close to the plane of focus.</p> Link to comment Share on other sites More sharing options...
michael_elenko Posted December 2, 2011 Share Posted December 2, 2011 Doug, Not good. Advice: return it. ME Link to comment Share on other sites More sharing options...
lauren_macintosh Posted December 2, 2011 Share Posted December 2, 2011 <p>the moment you saw the oil slick that's the time to call or write that party A>S>A>P</p> Link to comment Share on other sites More sharing options...
pj_vesterback Posted December 2, 2011 Share Posted December 2, 2011 <p>That is normal. The autofocus needs some sort of contrast to pick up.</p> Link to comment Share on other sites More sharing options...
michael_kuhne Posted December 3, 2011 Share Posted December 3, 2011 <p>This lens is one in a very high class of lenses. If it were me, only a perfect one would be acceptable. </p> <p>I cannot imagine what could have happened to cause the condition you describe, but mishaps do occur, and someone is trying to get rid of the problem by selling it off, it would appear. Any fluid or substance of any kind in the mechanism is a bad sign. It can easily cause malfunction and improper exposure, at the very least. Maybe even a total breakdown of function. If not now, then sometime down the road. </p> Link to comment Share on other sites More sharing options...
ariel_s1 Posted December 3, 2011 Share Posted December 3, 2011 <p>First, the autofocus racking is normal. If you show the camera a scene with no contrast, it will just hunt. That's true for any camera for any price. You are asking it to autofocus, yet not giving it something to autofocus on, so your K-r is trying as hard as it can to go through the focus range to find something. This is your camera's behavior by the way, and not the lens' behavior; it is not indicative of any malfunction with your DA 70mm. Second, about the oil spot, does it actually affect anything? There have been countless times when a lens is released online, and overzealous users with magnifying glasses have found a "problem" with their lenses. The most recent that I can recall was the Nikon 70-200mm "flaking" incident. Perhaps, you may want to go to a local camera repair shop and have them take a look at the lens, they will usually do so for free.</p> Link to comment Share on other sites More sharing options...
doug_nelson3 Posted December 3, 2011 Author Share Posted December 3, 2011 <p>Thanks to all for your help. The seller has agreed to take it back, even though there was a 'no returns" in the ad. It looks as if he sells a lot more stuff than photo gear and that he never removed the rear cap.</p> Link to comment Share on other sites More sharing options...
r.t. dowling Posted December 3, 2011 Share Posted December 3, 2011 <p>Very nice of him to agree to take it back if he had "no returns" in the ad. I'd say you lucked out!</p> Link to comment Share on other sites More sharing options...
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