Weird 550D AF, back/front focus at long distance, but OK at close distance

Started May 9, 2011 | Discussions thread
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ashyxt
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Weird 550D AF, back/front focus at long distance, but OK at close distance
May 9, 2011

hi guys, I have an early batch 550D

I have 3 lenses:

EF-S 55-250 IS - early batch serial no. 37002037
Helios 44-2 58mm f/2 M42 converted to EF with EMF-chip-adapter

they both focuses SPOT ON at minimum focusing distance, but at long distance, the DOF is shifted backwards on the EMF adapter, resulting in backfocus, BUT it's shifted forward on 55-250 IS, WHAT THE HELL?!?! O_O

to make things even more complicated, I also have a Sigma 17-70 OS HSM, at 40mm~70mm, it front focuses at minimum focusing distance but it's fine at long distance, goshh.....

has anyone experienced this???

thanks in advance for any input...

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