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Archive 2011 · Consistent front focus wierdness
  
 
mark petri
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p.1 #1 · Consistent front focus wierdness


Well the new 5d markII arrived and while i'm not normally a pixel peeper, I did some shots of the trusty ruler while on the tripod, center point AF, etc @ 45 degrees. Just about every lens was front focusing by around 1/2". Never noticed it with my prior body (Dsmk3),but then again never really looked for it either. Wondering if it's the body AF ior all my lenses are off now... opened a can of worms.


Dec 16, 2011 at 01:17 AM
rscheffler
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p.1 #2 · Consistent front focus wierdness


If it's consistently in front, then there's not much weirdness going on, you probably just need to MFA it. But I'd suggest first using it in a variety of situations common for you, checking the images for any issues, then deciding whether or not to MFA.


Dec 16, 2011 at 01:28 AM
mark petri
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p.1 #3 · Consistent front focus wierdness


Correct me if I'm wrong, MFA is at least in theory is intended to dial-in small AF adjustments due deviations in AF on a per lens basis correct?

If so, I find it had to believe 8 or so different lenses all being off by roughly the same amount, thus I was guessing it would likely be the body and not the lens. Yes, of course if they are all off by x, I can dial in by that mount to solve the symptom (assuming it's consistent when stopped down), but was speculating more on the root cause.



Dec 16, 2011 at 01:36 AM
TrojanHorse
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p.1 #4 · Consistent front focus wierdness


Mine all seem to be off by +5 although one is +10 and one is about 0.

It doesn't take much to be "off" by +5, I'd just set your lenses and carry on. If they were all +20 I'd worry.



Dec 16, 2011 at 01:55 AM
 

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mark petri
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p.1 #5 · Consistent front focus wierdness


Ya, you gents are right- I suspect that in my normal shooting, i would hardly if at all notice it. Cheers!


Dec 16, 2011 at 02:55 AM
scalesusa
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p.1 #6 · Consistent front focus wierdness


If all lenses are off, you can adjust the MA for the body and all lenses will be adjusted. Its not just for adjustment of individual lenses. The calibration of each body can vary, so use the tool provided and your images will be what you expect.


Dec 16, 2011 at 06:57 PM
Ferrophot
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p.1 #7 · Consistent front focus wierdness


Yes, you can adjust MA for all lenses or for each individual lens. My camera seems to need a consistent +6, but there are some small variations from this for one or two individual lenses. I didn't use the "all lenses" adjustment, I did each one individually.


Dec 17, 2011 at 07:12 AM
BrianO
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p.1 #8 · Consistent front focus wierdness


mark petri wrote:
...I find it had to believe 8 or so different lenses all being off by roughly the same amount, thus I was guessing it would likely be the body and not the lens.


You are correct. It could be from a manufacturing tolerance in the lens mount, a difference in the distance of the AF sensor versus the image plane, etc.

Whatever the cause, though, unless it's extreme you can correct it with MFA rather than sending in the body for recalibration.



Dec 17, 2011 at 08:41 PM





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