Improper sensor calibration?

[Rooster]

In my other thread involving that "soft" look to all of my images, I complained that I haven't gotten one sharp image from my Canon 20d.
Well I took a few sample images and sent them in to the lab/camera store in my town. They admit that the images should've been sharper. And took more samples there with my camera and lense, along with a diferent lense. Also they used another body on my lense.
The tests showed that the only bad images were coming from my 20d body. They sited that 2% of all 20d's hit the shelves with a defect. And mine was one of them. The defect is improper sensor calibration. Like the sensor is set to high, and should've been recessed a little lower in it's slot.
I don't know if that's true or not. But they gave me a new body and lense and I took about 135 pics in New Orleans today and they all turned out fine....well as far as sharpness goes. I ended up tossing about 60 of them do to me over or under exposing.
Happy ending.

 

[Tim_axe]

Improper sensor calibration is possible. It is basically where the sensor plane is not parallel with the plane of the lens mount. Generally Canon uses some very thin washers between the sensor's mounts and it's cage (or was it the cage and the camera body?) to keep it properly aligned/flat, but it is quite a manual process.

It should have no impact if the sensor is in the right plane but sits too deeply in it's space. That can be compensated with autofocus. But there is no solution to not having it be flat / aligned correctly. Afterall, flatness & correct alignment are perhaps the major advantages digital has over film.


So fortunately you get a new body and don't have to worry about the other problems that the other body could have developed that are related to having a damaged chassis or some other overlooked issue that is related to keeping the sensor plane where it should be.

Just hope you don't run into a lens whose elements are not centered correctly. That isn't pretty either...