Canon: Micro-Adjustements, How Often?
Many people will micro-adjust their lenses as soon as they buy/receive their new lenses. But… How often should readjust the micro-adjustments?
Canon 7D C.Fn III - 5: Micro Adjust Screen
Lately, I noticed that many of my photos were slightly out of focus. Either it's an operator problem, aka me, or the camera. After investigating, I found that I started the problem.
At Reifel Bird Sanctuary, I usually go into the “warming hut” to unpack my bag, get the camera out, mount the lens, mount everything on the monopod… Then, I go out and “do my stuff.” The problem is that now it's winter and the camera/lens combo goes from around 0° Celsius (around 32°F) to +18° Celsius (around 65°F) in the warming hut and back to 0° Celsius in a few minutes. I make sure that there's no humidity/dew on the camera/lens. But that wasn't good enough.
What's the purpose of the micro-adjustments
To account for the variations/tolerances of the manufacturing process. So when the lens reports focus, the camera can adjust ± to the data sent by the lens.
So one day, after coming back from Reifel Bird Sanctuary, I checked my micro-adjustments. They were off. No too much but enough to make many photos slightly out focus. I had to add a +3 to all my lenses.
Back to “how often to recalibrate the micro-adjustments?” Anytime there are “major” difference in temperature. Some lenses are more sensitive than other, you can see it by reading the focusing distance scale. You will see that most lenses go past the infinity to account for the change in temperatures.
BTW, this applies not only to Canon cameras, but also to Nikon, Sony, Olympus…