canon 55-250 IS blur edge, anyone?

jongpl wrote:

Ya I totally agree with you on the proper method of testing the lens.
But I think after all there is nothing that I can do to fix the lens
which I assume that it has a problem(or even my camera), so I decide
to send to canon. But I really apprieciate all the suggestion that
every each of you gave. Thanks.

I understand your comment that you don't want to shoot test situations that you normally don't use. However, in this case, it is important to apply correct testing to figure out what is wrong. Otherwise, you just might get the lens back from Canon, not being the wiser - and no doubt, the 55-250 IS is a good lens.

Thus, testing using no-real world conditions is an important point. If you know where the error is, it can be fixed.

I agree with the other comment that the palm tree at the bottom is a poor test object. It is much closer in front than the building, which would be the main object in focus. The palm tree could be easily out of focus, depending where the focal plane actually is, and how much DOF you have.

That's why the tripod test of something that is flat would be good.

Your idea of testing vertical, clock-wise and counterclockwise is good, since if you have decentering, once the blur should be at the bottom, then at the top.

Indeed, the first 70-300 IS lenses from Canon did have an IS problem when the camera was used in vertical orientation. Images became all blurry, Canon had to recall and fix it.

Now, we don't know what is going on in your case, it looks indeed strange and like a real problem, but there is not enough data to be sure.