40D Sensor Problem?

[Darren Mathews]

I took some pics today saving in RAW + L(jpg) format. I then imported them to iPhoto 09 and used the left/right cursor keys quickly switch back and forth between the two for comparison.

I was surprised by the color richness in the RAW pics and think I'll shoot RAW from now on.

Problem: The JPG format pics had a noticeable gap of missing pixels running the entire width of the camera when pics were taken holding the camera horizontal. Switching between the two pics to compare, you can see the JPG pic shifts the bottom 1/4" or so of the image UP overlapping a few tiny rows of pixels. It's very noticeable when quickly switching back/forth between the two pics on screen. I might not have otherwise ever noticed it since I had previously shot only in JPG mode.

Any thoughts? Should I send it to Canon for repair?

[natek313]

I'm not much of a guru when it comes to the guts of camera systems, but the problem only showing up on your JPEG images doesn't really indicate a problem with the sensor. I would think that if there was something wrong with the sensor that it would show on both the RAW and JPEG images. Perhaps there is an issue with the processing the camera performs to produce the JPEG files. The camera doesn't do as much processing on RAW files, so that would make sense it wouldn't show up on the RAW files.

That's my take. But, like I said, I'm not a guru. If I'm wrong, hopefully someone will correct me.

It may help to post the two pictures so everyone can see what you are referring to.

[sybren]

Your sensor has no multi-colour pixels. Every pixel either records red, green or blue. The other colours are "created" by interpolating neighbouring pixels. This means that around the edges you have a problem, because then there are no neighbouring pixels in a certain direction. This is solved by simply cropping the edge off your photo. Your camera may do this cropping differently than the software reading the RAW file, hence the difference.

Then again, this is all very nice and good to know, it doesn't apply to a row of pixels not on an edge. I would go back to the camera store and discuss it with them.

[Darren Mathews]

The image is being affected about 100 px from the bottom, horizontally through the entire image, it's like it takes the bottom 100px and slides them up overlapping an entire row of about 5-10px high. Again, only in JPG. Probably something wrong with how the camera is processing the image like natek313 says.

I'll have it checked out I suppose.

Thanks!