My copy is coded UZ (made in 2011).
Firstly I'd like to say that this lens is SUPERB!!!
Unlike most people's reviews which are generally quite disappointing, I find that this lens is made for certain field of usability. I have only purchased this lens last month, and used it as I travel Melbourne.
Some people run backfocus tests using line charts and uncover the focus shift problem at shorter distances wide open. My finding is that if you focus on something that's smaller than the camera viewfinder's red focus point (such as the line chart for example) , you get 50/50 chance of correct focus if used wide open (f/1.2 - f/2.0). This is NOT a macro lens (it doesn't have macro focus capabilities like the 28-135mm f/3.5-5.6 USM for example) so you will find it quite hard to obtain consistency results on small objects shooting wide open. There are reasons why people use this lens mostly on people (hence the saying 'portrait lens' stuck) - or street photography, in my case-. They dont require critically sharp objects in shallow depth of field, which is required for, say, food photography (though you can use this lens for just about anything if you equip your camera with an external flash guns, such as the 430ex).
The ideal objects for this lens would be those measuring approximately as big as a human head, framed horizontal above the waist. When you shoot people waist-up, try to focus on the face and you will get quite consistent result. The camera - object distance would be 3-4 feet away and even combined with f/1.2 you will still get acceptable sharp face part (eyes-nose-hair). If you need to frame full body length, the DOF will be wide enough to contain the body as well (according to my experience)
Also, my find is that this lens is not quite sharp at higher ISO (800-3200), but this phenomenon, I think, is more likely due to the camera's sensor not the lens. High ISO tend to soften the edge contrast, therefore if you shoot under lowlight (nightshots), indoor and handheld (at a banquet for example) this lens is no better than the average L series zoom lenses.
In the first few days, I frustrated over its inconsistency results, as well. I hook the lens with the 1Ds and tried to shoot some objects in my bedroom, handheld and under lowlight situation (without external flash) but cannot get the sweet spot while wide open (f/1.2 - f/2.0). I cannot determine the amount of micro adjustment needed with the 1Ds body as well because the results vary and greatly random at all adjustment (Believe me, I tried them all...). Then I change the body with the 7D knowing that longer MFD might get conclusive results. I then found that the lens backfocus by -18 in Micro Adjustment while shooting at MFD up to 3 feet away using the 7D. I exchange the body with 1Ds again, but still cannot support my finding in the 7D.
Come morning, I open my studio and set up a single light - single object scheme. I hook up my Hensel remote trigger to the 1Ds and set the numbers to 1/200 - f2.8 - ISO 100. (I chose f/2.8 since it's the widest I can go with consistence results) The tests results are quite explanatory, but if you dont want to download the big files just to proof I'm correct (:p), here's the steps I did :
( TO BE REVISED SOON )
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| AF-20 f/1.2 ISO50 1/200sec (4714) |
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| AF-20 f/2.8 ISO100 1/200sec (4721) |
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| AF-20 f/2.0 ISO100 1/200sec (4722) |
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| AF-20 f1.4 ISO100 1/200 sec (4723) |
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| AF-20 f/1.2 ISO100 1/200sec (4724) |
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| f/11 ISO400 1/125 sec (4757) |
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| AF0 f/5.6 ISO200 1/125 sec (4758) |
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| AF-18 f/5.6 ISO200 1/125 sec (4759) |
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| AF0 f/2.8 ISO125 1/200sec (4761) |
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| AF-18 f/2.8 ISO125 1/200sec (4771) |
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| AF0 f/2.8 ISO125 1/200sec (4780) |
I have tested, re-tested & re-tested again (with 1Ds mk3 & 7D).Now, the test above wasnt meant to scrutinize all the pros and cons of the 50mm f/1.2L USM, but simply to proof that mine doesn't back focus, especially at f/1.2. That's it. All else are secondary. I believe no lens are 100% perfect let alone a $1500 prime which has so many pros (color rendering / built / sharp) beside the notorious focus-shift problem. Sure, $1500 is a LOT of money, but to say expensive or cheap are subject to relativity. For me, though, that amount of money is equal to 5 jobs (and I'm no famous photographer), so I can safely say that anyone entering the photography business should be well paid enough to afford the lens. Since this is one of Canon's fastest lenses, it's quite mandatory to own one, dont you think :P~~
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