Microadjustment and the 7D

I note with interest that several people have had to microadjust some of their lenses when using them on the 7D. I am curious as to how much adjustment each person has had to make on the -20 to +20 scale and for which lens.
Is there an amount you would consider excessive, i.e. +20.

Hi Colin

I think in general it is benificial to MA, rather than necessary.

I found in general most lenses on the 7D benifited from a +1 to +5 adjustment with on at +10.

All these lenses were fine on the 20D which could not MA.

A hint if you are trying to MA and finding very large adjustments seem needed, try repeating the test further away (50X the focal lenghth at least). I found some non-L lenses were inconsistant at close distances and this could give over readings if trying to MA.

Colin,
Also keep in mind that while the 50x focal lenght rule is a good start, it's best to microadjust your lenses at a subject distance that you use that particular lens the most.

All but one of myu lenses benefited from MFA. The were all in the 0 to +10 range with the 100-400 needing the most at +10. 100mm and 17-55 were +5 and i can't remember all the others but they were in that range as well. On my 50D it was similar, the 100-400 neede +10 there as well.

I have noticed that the shorter focal length lenses are much more difficult to MFA and a change in value is much less noticeable. With the long lenses a change in just a few increments is very noticeable.

I have also given up on shooting the inclined plane focus chart and have had much better and more consistent results shooting a standard flat focus chart. It wont tell you which way to adjust and you have to take several pics and interpolate the offset, but finding the sweet spot is much easier. THis is a pic of my 100-400 with no adjustment and with an adjustment of +10. I also have a +15 and +20 and the +20 shot looks almost identical to the no offset shot. If you look at the bars and numbers it's hard to tell the differance but if you look at the resolution strip, one MFA value clearly stands out from another.

Just be aware that with zoom lenses, you'll get two different values, one at each extreme. I always write them on a piece of painter's blue tape that I stick on the back of the camera. If I know I'm shooting toward the long end of the zoom range, I set the MA for the long extreme, and vice versa.

VERY good point, that's my experience too, and I too made notes of MFA at the min and max FL of my zoom lenses.

tvphotog wrote in post #9188238
Just be aware that with zoom lenses, you'll get two different values, one at each extreme. I always write them on a piece of painter's blue tape that I stick on the back of the camera. If I know I'm shooting toward the long end of the zoom range, I set the MA for the long extreme, and vice versa.

Can you do a custom setting that includes this so you can quickly and easily switch?

jgrussell wrote in post #9188504
Can you do a custom setting that includes this so you can quickly and easily switch?

Yes. C.Fn III: Autofocus/Drive. That's how I do it.

gjl711 wrote in post #9188182
I have also given up on shooting the inclined plane focus chart and have had much better and more consistent results shooting a standard flat focus chart. It wont tell you which way to adjust and you have to take several pics and interpolate the offset, but finding the sweet spot is much easier.

+1 in fact I resorted to using my SRF/MTF lens test software to make it easier to compare multiple focus operations.

I found the sloping chart method very confussing and unreliable, this was perhaps me but whatever works.

tvphotog wrote in post #9188596
Yes. C.Fn III: Autofocus/Drive. That's how I do it.

Can you elaborate on what you mean?

I am not aware of any short cuts???

I frequently use a 300/2.8 + 2x tc for bird photography, what method of MA would you guys advise for this set-up? I was thinking about setting up some kind of target from around 30-40 feet and taking a series of of shots at different MA settings with the camera/lens mounted on a tripod - would this be the way to go?

Is that your typical working distance Roy?

I would suggest trying your typical distance and move further back if results are inconsistant.

I found the 200/2.8 + 2X was consistant at much less than 50X focal length.

I tried to do all my test indoors to avoid wind vibration issues on the target, which would tend to act like a sail. I think that is the main issue with a large and thus outside range for longer lenses.

Lester Wareham wrote in post #9193392
Is that your typical working distance Roy?

I tried to do all my test indoors to avoid wind vibration issues on the target, which would tend to act like a sail. I think that is the main issue with a large and thus outside range for longer lenses.

I take your point about wind Lester, I guess if doing a test outdoors you would need a calm day.
The trouble with birds is that the typical distance would be anywhere between 20-100 feet depending on the size of the bird (and how near I can get). Would it make sense to use the two extreme distances and average the results?

Roy C wrote in post #9193415
I take your point about wind Lester, I guess if doing a test outdoors you would need a calm day.
The trouble with birds is that the typical distance would be anywhere between 20-100 feet depending on the size of the bird (and how near I can get). Would it make sense to use the two extreme distances and average the results?

I found it difficult to get a clear MA effect at much longer distances, but for 600mm 50x focal length is of course 100ft.

I tended to bias towards my closest working distance and use the minimum adjustment I could. For longer distances and infity I just checked for consistancy using live view.

there no easy way for us Birders Roy as we get big birds close and distant, and the same with small birds
I set my 500 at about 60/70ft ,dof is greater the further away from your subject and most birds are indeed further away, i just think the above gives the best overall MA for real life shots.
Also when a birds close say 20/30ft away its easyier to see you have your focus point on the eye SO after setting MA as above i just check its not a mile out on a close subject .ie a some clear writeing on a box at around 30ft away.
best to use a remote, fast shutter, tripod, to rule out camera shake when doing the MA.

Rob.