I just bought this lens and a brand new 5DII and have had no issues at all with the 70mm Sigma macro (smack on focus, etc), but the 24mm is another story:
It seems to focus erratically. I can shoot five identical frames at infinity and at least half will be out of focus; some by a lot. I cannot predict when it will lock on accurately. Same prob at middle distances. Sometimes every frame is sharp. Sometimes every frame is soft even when I refocus for each one!
It focus shifts a hell of a lot up really close. Like many inches (front).
It seems not to need any micro adjustment at most distances, but if I adjust for up real close, it is out at infinity and middle distances.
It repeatedly grabs accurate focus on crisp detailed subjects at middle distances and is very sharp by f2 and very good at 1.4.... but point it at a human face and it usually misses focus. Even at 1-2m and f4 frames are usually soft. Put a beer can at the same distance.... perfect focus.
I dont get this. It can focus accurately one minute then two hours later I can do some more shooting and it consistently misses. Its as if lighting, subject colour, light levels are messing with it.
The sigma, you guessed it, smack on. Always.
I am figuring the issues is not withe the body but the lens. Its so inconsistent I dont even know the cause or even factors for sure. Optically its incredibly good, but if I cannot be remotely sure of accurate focus, whats the point?
Any thoughts? Head of this erratic focus before?
It seems to focus erratically. I can shoot five identical frames at infinity and at least half will be out of focus; some by a lot. I cannot predict when it will lock on accurately. Same prob at middle distances. Sometimes every frame is sharp. Sometimes every frame is soft even when I refocus for each one!
It focus shifts a hell of a lot up really close. Like many inches (front).
It seems not to need any micro adjustment at most distances, but if I adjust for up real close, it is out at infinity and middle distances.
It repeatedly grabs accurate focus on crisp detailed subjects at middle distances and is very sharp by f2 and very good at 1.4.... but point it at a human face and it usually misses focus. Even at 1-2m and f4 frames are usually soft. Put a beer can at the same distance.... perfect focus.
I dont get this. It can focus accurately one minute then two hours later I can do some more shooting and it consistently misses. Its as if lighting, subject colour, light levels are messing with it.
The sigma, you guessed it, smack on. Always.
I am figuring the issues is not withe the body but the lens. Its so inconsistent I dont even know the cause or even factors for sure. Optically its incredibly good, but if I cannot be remotely sure of accurate focus, whats the point?
Any thoughts? Head of this erratic focus before?