Help over L-series lens quality

I would like to get some help since I’m about to have a crisis over a lens which I purchased some months ago. It’s a Canon EF 28-300 L IS USM. Recently, I had its front lens element replaced by Canon in Montreal They also said that they cleaned the other internal lens elements.

After taking it out yesterday on assignment, once I returned, dumped the raw in the computer and I almost fainted. All shots were unsharp to what seemed to be as motion blur. Was I that tired yesterday? Did the IS malfunction?

So today, I decided to perform a simple test and compare this $3100 lens to a cheap $75 lens.

Both shots were mounted on a tripod, remote control and mirror lockup prior to exposure. Both front and rear lens elements were spotless with no filters attached. Focus and exposure is on the center point, pointed to the dash (-) of "Notre-Dame".

Pictures with full EXIF metadata are here:

Cheap consumer lens:
http://www.qpphoto.com​/temp/cheap-lens.jpg

Canon EF 28-300 L IS USM lens:
http://www.qpphoto.com​/temp/expensive-lens.jpg

I understand that some of you will say that the 28-300L is not the sharpest lens in the drawer. But its performance against any cheap lens is not justified. In this test, the $75 cheap lens outperforms, hands down the L-series lens. The cheap lens is very sharp, compared to the blurry photo of the L series lens. Not to mention that the cheap lens required less light to capture the same scene. (1/320s @ f/6.3) vs. (1/250s @ f/5.6)

What could possibly be the problem? What is the exact technical wording of the problem? It’s not motion blur, its not fringing, what is it? so that I can take it to Canon, for a second time, and tell them. Any input is greatly appreciated.

With my browser, I can't see any EXIF data, so I can only guess.

I had something like this happen to my camera ONE TIME. I cycled the power and the problem went away. At the time, I had made the guess that the problem originated in the camera body, but that goes against your thinking. On the other hand, if the aperture diaphragm were still in the process of closing down when the shutter was already flying, then that would explain something like you see.

Why would it still be in the process? It would be a sticky malfunction related to sticky lubrication, possibly from cold weather.

I'm just guessing.

---Bob Gross---

Had you turned IS off before your tripod test?

I tried with both IS and without. It doesn't make any difference. I think that something is misaligned. The problem is not only on the tripod, but also on monopod and handheld. I'll take it to Canon again and ask them for a resolution test and verify alignment.