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PentaxPoke · 08-13-2008, 03:06 AM

Originally Posted by solarisdreams

Hi all,

Just put together a K20d and DA* 16-50 and am concerned about all the buzz about the defective rate on these lenses. I got mine from Amazon just a few days ago and starts with a 9029... How do I go abouts figuring out if my lens is a bunk one or a good one?

(I did some searches here but could not find the answer).

Thanks,
Vic

Take some pictures and compare the edge sharpness to the center. Test at different apertures and focal lengths. If one edge is sharper than the other it is decentered (Bad). If the edges are all very "soft" compared to the center, again it is bad. My first copy of the lens had the first problem, my second had the second problem. Who knows what the third one will have... Often brick walls are used for this test since you have a uniform surface that you can easily discern the problem. My lens defects were so bad, I could see the problems without a brick wall. I have 2 other threads on this, in this forum.

08-13-2008, 03:06 AM	#152
PentaxPoke Loyal Member Join Date: Jan 2008 Location: OK Gallery Photos: 0 Posts: 461	Originally Posted by solarisdreams Hi all, Just put together a K20d and DA* 16-50 and am concerned about all the buzz about the defective rate on these lenses. I got mine from Amazon just a few days ago and starts with a 9029... How do I go abouts figuring out if my lens is a bunk one or a good one? (I did some searches here but could not find the answer). Thanks, Vic Take some pictures and compare the edge sharpness to the center. Test at different apertures and focal lengths. If one edge is sharper than the other it is decentered (Bad). If the edges are all very "soft" compared to the center, again it is bad. My first copy of the lens had the first problem, my second had the second problem. Who knows what the third one will have... Often brick walls are used for this test since you have a uniform surface that you can easily discern the problem. My lens defects were so bad, I could see the problems without a brick wall. I have 2 other threads on this, in this forum. __________________ PENTAX K20D, PENTAX K10D, PENTAX SMCP-DA 10-17, PENTAX DA* 50-135 f/2.8, PENTAX SMCP-FA 50mm f/1.4, PENTAX SMCP-FA 35mm f/2, PENTAX SMCP-DA 18-250mm f/3.5-6.3, PENTAX SMCP-DA 14mm f/2.8, TAMRON AF 90mm f/2.8 Di SP macro, TAMRON SP AF 17-50mm f/2.8 XR Di-II, PENTAX AF360FGZ flash, PENTAX BG2 grip.