One way of doing it is to use a high contrast target pattern (black and white) on a piece of A3 paper glued to some board. This acts as an accurate focusing target. You need to set this up square on to the camera and lens at the appropriate distance so the focus point (centre) on the camera can lock on easily.
You can then lay a tape measure/long ruler alongside the target board (at a slightly sloping angle so it can be seen in the viewfinder as well). When you take a shot of the focusing pattern and look at the image on the screen or pc you should be able to see the ruler and work out which bit of it is in focus. If it is front/back focusing you should be able to see this and correct in in camera by repeating.
I should add that you should use a tripod, and remote/timed release along with the widest aperture possible to get the best results. Its also worthwhile manually defocusing the lens before you AF on the target.
You can buy a gadget called Lens Align (fairly pricey) which does the same job. The link might help to explain what I've said above. http://www.lensalign.com/
Posted by Mike Smith on February 25, 2010 at 6:21 AM
As per Simon, but don't get forget that it is normal for there to be a 33:66 (or is it 66:33?)spread compared to 50:50 split between front/back depth fo field when AF is working properly.
A quick test without setting up the focus target & angled ruler is to use S-AF on your bank note then go into magnified live view and see if the focus needs tweaking. If it does it suggests the AF sensors in bottom of the camera body and plane of the image sensor are not in true distance registry (or the reflex sub mirror is giving an unequal projected image distance).
I haven't a clue if "12" is a big adjustment or not
Discussion
4 repliesnot done this before, so i stuck a 5 note flat on a wall.
left VR on, and used a remote shutter release. ISO200 and JPEG as the file type.
it looks like i need +12 on my lens. which seems alot to me. the lens is fairly new. the body is second hand.
But + 12 seems to reproduce the sharpest details on the bank note.
I am not sure if this is the correct way of doing it, or can anyone else please give me some advice on how to do Fine AF adjustment correctly.
Mark.G
You can then lay a tape measure/long ruler alongside the target board (at a slightly sloping angle so it can be seen in the viewfinder as well). When you take a shot of the focusing pattern and look at the image on the screen or pc you should be able to see the ruler and work out which bit of it is in focus. If it is front/back focusing you should be able to see this and correct in in camera by repeating.
I should add that you should use a tripod, and remote/timed release along with the widest aperture possible to get the best results. Its also worthwhile manually defocusing the lens before you AF on the target.
You can buy a gadget called Lens Align (fairly pricey) which does the same job. The link might help to explain what I've said above. http://www.lensalign.com/
A quick test without setting up the focus target & angled ruler is to use S-AF on your bank note then go into magnified live view and see if the focus needs tweaking. If it does it suggests the AF sensors in bottom of the camera body and plane of the image sensor are not in true distance registry (or the reflex sub mirror is giving an unequal projected image distance).
I haven't a clue if "12" is a big adjustment or not
Northern Lights AF adjustment
T
Simon