Stevec_UK
20th of June 2005 (Mon), 11:28
For anyone (like me) who has focus troubles with a DSLR and/or lens, here's
Canon's own text which states both camera AND lenses can be calibrated independently).....
http://photoworkshop.com/canon/EOS_Digital.pdf (http://photoworkshop.com/canon/EOS_Digital.pdf)
If it aint working - send it in...I could have believed that my 70-300 DO IS (bought used from a disappointed owner for a song) was doing its best within its "non-L" limitations and put up with it...now having sent it in to be fixed it IS doing its best and I dont feel as if I'm putting up with anything any more.
For this particular lens, there was a camera comms fault that meant focusing sometimes worked and sometimes "almost" worked - leading to inconsistent results.
Extract from the Canon doc:
If the camera and lens are being operated correctly, but images remain consistently out of focus, there is always the possibility that the camera or lens is not performing according to factory specifications. EOS cameras and EF lenses are precision instruments, and as such they require precision adjustments to perform at peak efficiency. Although Canon makes every effort to calibrate the AF systems of EOS cameras in the manufacturing process, a small percentage of cameras require calibration adjustments at the Factory Service Center (FSC) after sale.
AF system calibration at the FSC involves a series of tests to determine the positioning accuracy of mechanical components such as the image sensor and reflex mirror assemblies. Once these potential problem issues have been eliminated, test images are taken using a “tool lens” with known performance characteristics. The testing method enables technicians to ensure that the camera is performing well within tolerances for AF accuracy. Once this has been done with the tool lens, it becomes possible to check the performance of other lenses the customer may have.
Because each autofocus lens contains its own microcomputer and many other internal devices such as focusing motors and diaphragm actuators, lenses occasionally require calibration. If a focusing error is detected, the circuitry of the lens itself can be adjusted to ensure that it is operating according to design specs. Calibrating a lens does not compromise its performance with other camera bodies because the calibration standards for the lens are independent from the calibration standards for the body.
Canon's own text which states both camera AND lenses can be calibrated independently).....
http://photoworkshop.com/canon/EOS_Digital.pdf (http://photoworkshop.com/canon/EOS_Digital.pdf)
If it aint working - send it in...I could have believed that my 70-300 DO IS (bought used from a disappointed owner for a song) was doing its best within its "non-L" limitations and put up with it...now having sent it in to be fixed it IS doing its best and I dont feel as if I'm putting up with anything any more.
For this particular lens, there was a camera comms fault that meant focusing sometimes worked and sometimes "almost" worked - leading to inconsistent results.
Extract from the Canon doc:
If the camera and lens are being operated correctly, but images remain consistently out of focus, there is always the possibility that the camera or lens is not performing according to factory specifications. EOS cameras and EF lenses are precision instruments, and as such they require precision adjustments to perform at peak efficiency. Although Canon makes every effort to calibrate the AF systems of EOS cameras in the manufacturing process, a small percentage of cameras require calibration adjustments at the Factory Service Center (FSC) after sale.
AF system calibration at the FSC involves a series of tests to determine the positioning accuracy of mechanical components such as the image sensor and reflex mirror assemblies. Once these potential problem issues have been eliminated, test images are taken using a “tool lens” with known performance characteristics. The testing method enables technicians to ensure that the camera is performing well within tolerances for AF accuracy. Once this has been done with the tool lens, it becomes possible to check the performance of other lenses the customer may have.
Because each autofocus lens contains its own microcomputer and many other internal devices such as focusing motors and diaphragm actuators, lenses occasionally require calibration. If a focusing error is detected, the circuitry of the lens itself can be adjusted to ensure that it is operating according to design specs. Calibrating a lens does not compromise its performance with other camera bodies because the calibration standards for the lens are independent from the calibration standards for the body.