Photophys.com: The Science of Photography

DSLR AF problems

Comments[0] 08:49PM Aug 07, 2009 by Charles in General

A friend recently found that his new Canon 50D seldom gave sharp images when compared with his 40D, and he sold the 50D.  This week I tested a new Canon T1i for AF focus accuracy.  I used my Canon 28-135mm, Canon 100-400mm, and Sigma 150mm macro lenses and the 45 degree Focus test chart published by Tim Jackson.  See: http://focustestchart.com/chart.html

I found that the T1i had a rather severe front focus problem.  The center point of focus was at the back edge of the sharp focus region, and points a few cm closer to the camera were in perfect focus.  Manual focus, aided by live view, produced perfectly focused images.  In contrast, AF on my Canon XTi and 40D was very good.  Unfortunately, the T1i does not have AF Micro adjustment, and the new owner must either return the camera to the vendor or send it to Canon for calibration.  My recommendation is that you test your new DSLRs for AF focus accuracy immediately after purchase.  These cameras are capable of excellent images.

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