The area of sensitivity for most focus points in most configurations are much larger than the indicators seen through the viewfinder.Ī map of the EOS 5D mark II focus system. Other AF systems in modern DSLRs are similar. Even when a camera/lens combo is adjusted just as well or even better than with the LensAlign system, minor flaws will be visible in the test pictures of a flat target.Īppendix: Maps of two focus systems with which I am personally very familiar.
The flat target methods will reveal every minor flaw. I think one reason many people like the LensAlign system better is that when a body/lens combo is dialed in the shots of that test target will look very good and the user will feel confident the camera is in adjustment. Both will improve your AF accuracy if the original body/lens combo is off by more than 3-5 AFMA adjustment points. Then tape your test target to the mirror with the center of the target on the spot your camera is already pointing at.īoth methods have their strengths and weaknesses. The easiest way to do this is to choose a sturdy, undistorted wall mounted mirror and adjust the camera position until the Center Focus Point is aimed at the center of the camera's lens in the reflection. Even if you are not using the FoCal software, to use a flat target it must be aligned. It has a module that assists you with getting your camera and target aligned. The FoCal method uses a flat target which must be in a parallel plane with the camera's sensor. Even cameras that don't have "hidden" focus points may not be very accurate in terms of having the focus array aimed at the exact spot indicated in the viewfinder. The location of these six AF Assist Points are not indicated in the viewfinder! Yet the camera may be using one of them pointed at something other than the flat part of the test target when it decides the focus distance. When shooting in AI Servo AF, if C.Fn III-07 is enabled, there are six small AF Assist Points clustered within the spot metering circle that are active in addition to the Center Focus Point.
For this reason I prefer to use AF adjustment methods that use a flat target.Ĭonsider the Canon 5DMkII, for example. If the center focus point on the focus screen does not accurately indicate the exact point aimed at by the focus array this can be problematic. The camera's actual AF point must be aimed closely enough to the point indicated by the square in the viewfinder to insure the actual point being focused is on the flat part of the target and not a point (usually on the ruler) that is closer or further than the flat target.The LensAlign unit must be put together perfectly "square".LenAlign is useful and in the right hands can get very good results.
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