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Old May 24, 2005, 12:20 PM   #1
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Good Morning all,



After watching the forums here and around for quite a bit I have decided to pick up the Sigma 24-70 DG EX f2/8 as my first addition to the kit and body.

While trolling around for prices I stumbled into this statement which I don't fully understand and thought some of the more informed folks here might have some insight "Was serviced and calibrated by Sigma and the new circuitry (flexboard) was installed"

They then go on to say, "Now its ready to accept all camera bodies, etc" I haven't ever seen anybody posting about circuitry problem or outdated software/hardware regarding this lens.

Anybody have an idea?

Thanks
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Old May 24, 2005, 1:46 PM   #2
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While I don't know what you're talking about, a flex circuit is a flexible mylar board that is used to mount electronics components on - Make sense, the lens is round, the circuit need to 'bend' around the glass elements and the outer barrel...

http://www.flexctech.com/compare.htm
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Old May 24, 2005, 3:11 PM   #3
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i have heard of this on their 70-200 2.8.. some of the earlier models of this lens needed "a new chip" to be compatible with the canon 10d and later bodies.. i suspect that this is the same w/ earlier models of the 24-70 2.8.. other than that i am not sure if it was all older models of the lens, or just certain batches.. but i do know that sigma will replace it no charge, no questions asked...
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Old May 24, 2005, 3:45 PM   #4
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Hards80

The 'new chip' only applies to non-HSM lenses... the 70-200 f/2.8 is an HSM and an EX 'Pro' series -> Theses lenses never did require any chip changes, check with Sigma

... the very older 70-210 series might need this but are long gone from production (or the market) :?
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Old May 24, 2005, 5:51 PM   #5
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all i have read is specific to the 70-200 2.8 EX HSM .. and that the very early versions of this lens needed the re-chipping because they had focusing problems with later model camera bodies from nikon and canon.. i have not talked with sigma, so it could very well be that what i read was wrong.. (the internet- best and worst place to get information)
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Old May 24, 2005, 6:36 PM   #6
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Yes, for the 20D, the 24-70 needed a new flexboard (which can be considered to be rechipping as that is where the chips are mounted - on the flexboard). Sigma is the only major 3rd party lens manufacturer that has this problem of chip incompatibility as camera bodies are updated. HSM/EX/APO/DL, it really doesn't matter, many Sigma lenses have had to be rechipped - there was an internet page that listed them but I don't have the URL anymore. When buying a used Sigma lens, you have to ensure that it is compatible with your camera body unless it is the current model of lens being marketed by Sigma. If the lens is current, they will rechip it. If it has been superceded in their lineup or no longer offered, they will not rechip it (happened to me).

The Sigma EX lenses are very good and you get a great discount compared to the Canon L lenses. Sigma also makes lenses that no one else does, like the 100-300 f4 and 120-300 f2.8 that are incredible. In those cases, you don't really have a choice but to buy Sigma because no one else has a lens that is close to what they are offering. In the 18/24/28-70/75 area, there are very good alternatives. If you don't mind that there is the very real possibility that the Sigma will become obsolete due to a chip incompatibility problem, it is a very good performer according to all the reviews I've seen after it's had the flexboard upgrade. But it just serves as a reminder that Sigma has historically had this problem.
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