AF microadjustment tricks

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arash_hazeghi

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I have seen many threads about micro adjustment and the confusion that comes with it. Do you need to pay for a fancy test target/ruler etc.? How do you figure what adjustment value to dial in? I thought I would share my tricks in case you are interested.
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There is a very convenient way to perform MA with Canon EOS cameras, all you need is a good sturdy tripod and head, a simple contrast target and a small mirror.
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First find a target that has fine high contrast features, you can print an ISO chart, a dollar bill or even a map but the target has to be perfectly flat. Pin the target to the wall at a distance ~25-50 times the focal length, for a zoom lens choose the focal length that you use most often. First use the spirit level on the ball head to level the camera in XY plane. It is essential that sensor plane is parallel to target. To do this you can use a small mirror, tape it to the target look through the camera’s finder until you can see the center of your lens in the mirror and lock down your tripod. Optical axis is now perpendicular to target and you are done with the mirror.
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You must have Canon EOS utility application installed on your machine, this is included with every canon camera, if you have an older version make sure to go to Canon’s website and download the latest update. You are ready for micro adjust now.
Follow these steps:

<!--[if !supportLists]-->1) <!--[endif]-->Connect the camera to your computer via the USB port, cancel any image download pop-up/application
<!--[if !supportLists]-->2) <!--[endif]-->Run EOS utility.
<!--[if !supportLists]-->3) <!--[endif]-->Click on Camera setting/remote shooting icon ( Fig 1 ).
<!--[if !supportLists]-->4) <!--[endif]-->Click on Remote Live View Shooting this will open a new window with live sensor video feed ( Fig 2 ).
<!--[if !supportLists]-->5) <!--[endif]-->Make sure AF is in phase detect mode (quick mode AF) that uses camera’s main AF sensor ( Fig 3 ).
<!--[if !supportLists]-->6) <!--[endif]-->Choose the center AF point and make sure the white rectangle is centered on the AF point, this illustration is for 5DMKII, AF points pattern will be different for different cameras.
<!--[if !supportLists]-->7) <!--[endif]-->Click on magnifying icon for a full size view ( Fig 4 ).
<!--[if !supportLists]-->8) <!--[endif]-->Click AFON button (Fig 4) the camera will now perform AF.
<!--[if !supportLists]-->9) <!--[endif]-->Click on a 200% magnification, you are now viewing sensor output at 2:1 ( Fig 5 ). Note it is essential that tripod be placed on a solid surface plus nobody should walk in the proximity of the setup or you will see vibrations on the screen!
<!--[if !supportLists]-->10) <!--[endif]-->Now click on the ( > ) or( < ) buttons to shift focus back or front one click at a time until image appears sharpest on the screen, notice the contrast edges, you want them as crisp as possible. Write down how many clicks you have moved relative to the center, infinity symbol indicates far direction ( Fig 6 )
<!--[if !supportLists]-->11) <!--[endif]-->Repeat this a few times until results are consistent.
<!--[if !supportLists]-->12) <!--[endif]-->Each click on the ( > ) or ( < ) corresponds to one unit in the AF micro adjust scale in the camera.
<!--[if !supportLists]-->13) <!--[endif]-->Disengage LV by clicking close in the Zoom View and Remote Live View Windows.
<!--[if !supportLists]-->14) <!--[endif]-->Go to MA menu option in your camera and dial in the exact value noting the back or front direction.
<!--[if !supportLists]-->15) <!--[endif]-->Go back to step 3 and perform AF again, if image is already as sharp as possible when you click 200% you are done, if not iterate until you can repeatedly get the sharpest image. You can shoot test images and transfer directly to your computer( Fig 7).
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Your camera and lens static AF should be adjusted with great accuracy now.
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Fig 1

MA1.jpg
 
Thanks for all the work and the details. I've been reviewing threads on different sites and people who have tried MA seem to feel that it only works at the distance they adjust for but when they bring it to the field they see the same problems. The manuals (MarkIV) dissuade owners from using lest you "prevent correct focusing from being achieved". I am confused about MA. Can you straighten me out on this?
 
Thanks for all the work and the details. I've been reviewing threads on different sites and people who have tried MA seem to feel that it only works at the distance they adjust for but when they bring it to the field they see the same problems. The manuals (MarkIV) dissuade owners from using lest you "prevent correct focusing from being achieved". I am confused about MA. Can you straighten me out on this?

The other problem Andrew is that with zoom lenses the MA may be focal length specific.
 
Arash -
Looks like a simple, inexpensive technique - thanks for sharing it.

A couple of questions:
12) Each click on the ( > ) or ( < ) corresponds to one unit in the AF micro adjust scale in the camera - - - did you work this out by trial and error, or get the info from Canon?

Have you tried the technique at different distances (minimum FL, 25 x FL, 50 x FL ) - - are the results consistent for a given lens
 
Thanks for all the work and the details. I've been reviewing threads on different sites and people who have tried MA seem to feel that it only works at the distance they adjust for but when they bring it to the field they see the same problems. The manuals (MarkIV) dissuade owners from using lest you "prevent correct focusing from being achieved". I am confused about MA. Can you straighten me out on this?



Hi Andrew,

As John mentioned for zoom lenses you can do this for one FL at a time so while it might improve for that FL it might get slightly worse for other FLs. Also MA only corrects consistent back or front focus issues, it is not going to help with random AF misses or soft images in AI servo mode, the first thing to do is to make sure that the lens/body are indeed front / back focus, if you want to use this method make sure that you defocus to infinity press ( >>> ) button and then AF-ON button again several times to verify there is a consistent shift in focus plane. Then if you adjust accurately it should work for a range of distances at least.
 
Arash -
Looks like a simple, inexpensive technique - thanks for sharing it.

A couple of questions:
12) Each click on the ( > ) or ( < ) corresponds to one unit in the AF micro adjust scale in the camera - - - did you work this out by trial and error, or get the info from Canon?

Have you tried the technique at different distances (minimum FL, 25 x FL, 50 x FL ) - - are the results consistent for a given lens


Hi Peter,

Canon did not comment on this but the ( > ) appears to be a single-pulse servo stepping, i.e. the minimum amount that the focus element can move which should correspond to one "mirco" adjust step, it seems to be the case for 50D, 7D and 5DMKII

I usually try this at one distance and it appears to work for different distances in the field. One other point is try to center the the focal plane at the sweet spot, you will find that the image will still be sharp for 2-3 clicks within the best point so centering it will allow a bit tolerance as distance changes.

Arash
 
Arash
Again thanks, i have now calibrated/adjusted my 300f4 and 500f4 also with the 1.4 and 2x and what a difference and as you say easy and accurate consistent results......... Why do Canon not tell us to do it this way
 

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