50D Micro Adjust - A How To

I read a few other posts and articles on how to micro adjust different lenses and finally had the time to sit down and do it. I figured the best way was to use just the standard focus test chart at 45 degrees and an associated good working environment: lens at wide open aperture & longest focal length, solid tripod, release, good light, no kids.

With short lenses ( < 135mm ) I half pressed the shutter button, then hit the live view button, zoomed in to 5x and checked the focus. Adjust the micro adjust, repeat till it was right. Pretty easy.

With long lenses ( > 150mm ) It was too shaky for me to use the controls at 200mm without a lot of shake in live view so I just took a picture, zoomed in using image review (not live view) then adjusted the micro focus, and repeated if necessary.

I came up with the following numbers:
+2 - Tokina 12-24mm
+1 - Tamron 28-75mm
+2 - Canon 28-135mm
-2 - Sigma 70-200mm

For demonstration purposes here, with the 70-200 at 200mm I racked the adjustment factor to -20, -15, -10, -8, -5, -4, -3, -2, taking pictures of each. Here they are in an animated gif file. It'll repeat after 5 seconds at the end. (1.3mb)

Tripod.

Thank you for posting

I never had luck with the focus chart. To get good results I was adjusting much closer than I was using the lens. I found that real world subjects worked better. My 100-400 and my 70-300 I did in my backyard with a folded piece of paper for the target and the grass as my indicator. I found that moving the subject to the distance I mostly used the lenses gave me much better results. For the shorter lenses I used my living room run and a folded index card.

I did mine the cardinal sin way. I stacked 3 fake flowers 2" apart front to back and took picture of middle flower. When I went to the computer it was focusing on the front flower. I adjusted until middle flower was crisp and clean. I ended up with a +9 on my 70-200 2.8L and a +4 on the 28-135 kit lens.
I do have a question about using the charts. With the 70-200 how did you get far enough away to focus on it at 45*.

Thanks for the tips, I haven't even touch the micro adjustment on my 50D yet.

goose2 wrote in post #7357251
I did mine the cardinal sin way. I stacked 3 fake flowers 2" apart front to back and took picture of middle flower. When I went to the computer it was focusing on the front flower. I adjusted until middle flower was crisp and clean. I ended up with a +9 on my 70-200 2.8L and a +4 on the 28-135 kit lens.
I do have a question about using the charts. With the 70-200 how did you get far enough away to focus on it at 45*.

No sin, any items to determine what's in focus and what's not will work as long as there's enough graduation to tell where the focal plane is.

The minimum focusing distance on the 70-200mm is around 4ft IIRC. I was about 6ft away, camera eye level ~6ft, and the paper was on the floor.

This might sound stupid ( i seem to start most of my posts like that....) but when you microadjst a lens will it stay adjusted for other bodies? i.e my 50mm 1.8 seems to be front focusing, if i used a friends 50d to adjust it will it then be better on my body? IYSWIM

sancho1983 wrote in post #7446966
This might sound stupid ( i seem to start most of my posts like that....) but when you microadjst a lens will it stay adjusted for other bodies? i.e my 50mm 1.8 seems to be front focusing, if i used a friends 50d to adjust it will it then be better on my body? IYSWIM

No, the micro-adjust feature does not change the properties of the lens but mdifies the offset the body uses to focus so it stays with the body.

ok, cool thanks.

Nice post! Canon recommends to use a 50x factor to check for AF. So for your 70-200 (@200)

200 x 50 = 10000mm = 10m ~= 33ft.

http://www.digitaljour​nalist.org/issue0812/t​ech-tips.html

"...Camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens, that would be at least 2.5 meters, or approximately 8.2 feet. ..."

I have no idea about the 5X issue, but I'm pretty sure 1000mm does not equal 10m

lbridges wrote in post #7447934
I have no idea about the 5X issue, but I'm pretty sure 1000mm does not equal 10m

correct and added the link to chuck westfall.

silvex wrote in post #7447722
Nice post! Canon recommends to use a 5x factor to check for AF. So it is like for your 70-200 (@200)

(200 x 5)/100 = 10 m ~= 33ft.

lbridges wrote in post #7447934
I have no idea about the 5X issue, but I'm pretty sure 1000mm does not equal 10m

I believe that the Canon recommended distance is 50x, not 5x. 1000mm is 1m, considerably less than the minimum focus distance of the 70-200. At 50x though, It's still 10m.

gjl711 wrote in post #7447993
I believe that the Canon recommended distance is 50x, not 5x. 1000mm is 1m, considerably less than the minimum focus distance of the 70-200. At 50x though, It's still 10m.

The end results it is what WE are after...no matter how bad the math or methods are...