Following a number of complaints from customers, Canon has released a statement to confirm that certain DSLR users are having problems with certain Canon and Tamron EF lenses.
The problem sees users having limited function in the other auto focus points when the lenses are used with Canon DSLRs - EOS 7D, EOS 60D, EOS 50D and EOS 40D. The problem relates to the cameras peripheral AF points, which are cross types (horizontal and vertical sensors) and should therefore work together to produce more accurate results, but in this case are working separately and thus causing problems.
Canon’s German site confirmed (translated from German): “When using one of the eight telephoto lenses, the measurement fields work in the border area is not as cross-spot sizes, resulting in vertical and horizontal lines that are detected simultaneously. Vertical and horizontal lines are detected only separately.”
Explaining further the cause of the problem (again translated from German), Canon said: “This is due to the optical properties of the AF sensor and lens of the camera. If the maximum aperture value of EF lenses and EF-S lenses, is to 1:5.6, all measuring fields function as cross-field measurement, and vertical and horizontal lines are detected simultaneously.”
The lenses affected by the problem are: EF 35-80mm 1:4-5.6, EF 35-80mm 1:4-5.6 II, EF 35-80mm 1:4-5.6 III, EF 35-80mm 1:4-5.6 USM, EF 35-105mm 1:4-5.6, EF 35-105mm 1:4-5.6 USM, EF 80-200mm 1:4.5-5.6 II and EF 80-200mm 1:4.5-5.6 USM. Tamron has not confirmed the issues with its lenses, but Canon Rumours suggest the problems lie with the following models: 17-50 f/2.8 VC, 60 f/2 Macro, 70-200 f/2.8 and 10-24 f/3.5-4.5.
Canon also apologised “that this notice is not in the user manual of the respective cameras is displayed.” Have you had any problems with these lenses? If so, let us know in the comments.