XT 350d focus adjustment

For those of us who have attempted to do the focus adjustment via the knob near the sensor....

Was the screw very hard to turn and sensitive?

I found turning it one "squeak" resulted in a large adjustment of focus, on the order of 3 to 4 millimeters.

Also, did anyone else find that turning the wrench towards the canon logo makes the camera front focus more? I still adjusted it fine, but it took me longer to adjust the thing because I was making it worse when I was following the directions.

Well, 3-4mm means nothing without knowing the lens and distance to target, aperture, etc...

The spec on focus accuracy is +/- 1/2 DOF if I remember correctly. So, unless your DOF is 8mm, then this is probably not significant.

Finally, from all the testing I've done on my lenses - using a number of bodies but including the 350D, they are all sensitive to the amount of light. I never got repeatable focusing (i.e. perfectly centered DOF etc...) if I was using indoor lighting. You need to use outdoor lighting which is several stops stronger and offers more contrast.

Additionally, messing around with the shims under the focusing screen (Canon offers a whole slew of sizes for adjustment purposes) can impact focusing too (at least through the VF).

Unless you really know what you are doing, messing with that screw is liable to really screw up your camera. If you are not sure what if it is right or not, you'd be much better advised sending it in to Canon.

J.

hmm, tell me more about this adjustment screw...