Canon or Sigma for 50mm F 1.4 on 5D MkII ?

Started Jul 22, 2009 | Discussions thread
Jari Karppanen Regular Member • Posts: 326
Only focus issues I have are because of my camera

Occasionally the autofocus misses (sometimes badly). I own a 5D II and also the Sigma 50mm f/1.4. After studying the problem a while I found out that it's not the Sigma lens that's the problem, but my camera's sucky autofocus. With a slower lens (such as 24-105mm f/4L) you cannot see the problem as pronounced, but it's still there.

My camera simply makes small focusing errors constantly. On average it focuses properly, but If I focus 100 times using a test chart, I can clearly see the lenses' distance meter moving very slightly between some focus attempts, and sometimes the change is significant enough to cause a misfocused-looking shot.

I have no repeatable front/back focusing on any of my lenses, and most of the shots are properly focused. And, people are complaining about focusing problems with the Canon 50mm f/1.2 L, too. I don't own the lens, but it might be that the problem is the same: that is the camera simply cannot focus reliably. (I always use the center focus point only).

(I tried the focus adjustment offered by 5D II and after taking enough test shots, it seems no adjustment is necessary and that all of my lenses focus as they should -- but if you only take few test shots, you might think adjustment is needed, because those few shots just happened to be those that failed focus more than average, on either direction. You might actually hurt your focusing accuracy, because after adjustments, all the shots now miss by the adjustment amount (on average).)

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