Sig 30 1.4 / 50D Microadjust issue

Started Dec 14, 2009 | Discussions thread
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AustinROB
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Sig 30 1.4 / 50D Microadjust issue
Dec 14, 2009

Ok, I love my Sigma 30 1.4, it really captures some jawdropping images, but I hope that some of you can explain to me if I have an issue that can be fixed with a standard lens calibration from the manufacturer.

the issue with my Sigma is that it is frontfocusing OR backfocusing depending upon the focusing distance, for example:

At its closest focusing distance, the lens front-focuses by 7mm (easily adjusted with a +7 microadust on my 50D, but as the lens gets further form the focusing object, the lens begins to back foucs(for expample by the time the lens is 6 feet from the focus point, I have to microadjust for 8mm of backfocusing). So, this means that to get the best performance out of my lens, I have to decide which focus distance I will most liekly use most with this lnse and microadjust for THAT distance...in my case I've currently set it up for 6 feet of distance as my sweet spot.

So, my questoin is, will sending the lens back to Sigma for calibration fix this changing focus distnace issue??

Sorry if this has been answered before, I could harldey even think of how to explain this let alone search for it...

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