Micro Adjustment

[MikeMac]

Hi I noticed that my Canon 100mm 2.8 Macro was front focussing so I tried to do a Micro Adjustment using a Spyder Lenscal and the Micro Adjustment menus. The result between -20, 0, and +20 are hardly noticeable. Even at +20 the lens is till front focusing. Are such minute changes normal? See this link for photo http://www.outdoorphoto.community/forums/showthread.php?31928-Micro-Adjustments-Canon-CameraLens Any inputs appreciated. Michael

[jrhoffman75]

I don't know what camera you are using, but mine has a custom function that enables/disables using the AFMA adjustment values. Check for that.

[ebiggs1]

Micro adjustment can be very tricky. First you need to be a the largest aperutre.  You need to be 50x focal length from the target. ( about 16 feet)  You need a very stable tripod and a 'real' test target.

[RobertTheFat]

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@ebiggs1 wrote:

Micro adjustment can be very tricky. First you need to be a the largest aperutre.  You need to be 50x focal length from the target. ( about 16 feet)  You need a very stable tripod and a 'real' test target.

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I've done a fair amount of micro-adjustment, and I don't really agree. If you're a compulsive pixel peeper, then probably what Ernie says is true. But if all you're trying to do is get your pictures to look right, you just have to take a series of pictures at different AFMA settings and pick the setting at which the selected subject is the sharpest. What you should keep in mind is that if you can't tell the difference between two adjacent settings, it probably doesn't matter which one you choose. The settings are very close together, so getting it almost right represents a pretty high accuracy.