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Thread: Re-chipping old AF lenses

  1. #1
    Senior Member dhsimmonds's Avatar
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    Re-chipping old AF lenses

    There is an interesting article in the current issue of 'Photoworld' the UK magazine for Sony Alpha/Minolta SLR user club.

    The writer describes a DIY re chipping of an old Sigma AF tele 400mm F5.6 Minolta mount lens using a purpose designed chip from James Lao in China.

    It cost $60 including postage and four days to deliver. The only tools used were a pair of precision side cutters and a small Philips screwdriver. The lens was shown in use with an A900.

    Some very nice long APO fairly lightweight and inexpensive lenses can be adapted this way!

    The same issue also carries an article with some stunning ground to air shots using an A100 with Minolta 100-300 APO zoom lens mostly at max. zoom of 300mm. (Equivalent of 480mm used with an APS sensor)
    Last edited by dhsimmonds; 11th May 2009 at 06:22.
    Cheers, Dave
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    Senior Member douglasf13's Avatar
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    Re: Re-chipping old AF lenses

    I'm a little confused. Why would these lenses need rechipping, if they were Minolta mount in the first place? Thanks, douglas

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    Re: Re-chipping old AF lenses

    Sigma did a crappy job reverse engineering their chips. A lot of the old lenses don't work on newer cameras.

    But then, why bother? The lens won't last a week before it throws a gear tooth.

    No, I'm serious.

    Greg

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    Senior Member dhsimmonds's Avatar
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    Re: Re-chipping old AF lenses

    Douglas - The Sigma was designed before the latest Minolta system which morphed into the Alpha mount. These conversions can be obtained for a number of different mount systems including M42.

    Greg - The older Sigmas were very well built with gunmetal barrels, black flock lined lens hoods etc so I am guessing that the gears were similarly made. However, I have also heard that the modern Sigma's have plastic gears which the high torque Alpha motors can easily strip.

    I have asked Sigma reps this question in the UK and they dodged the question referring me to their technical guru's. I notice that only selective Sigma lenses are fitted with the Sony mount, others don't. So I haven't bothered to ask the question

    At the moment I wouldn't take the risk myself of using Sigma lenses on the A900. Sigma are renowned for dodging quality after sales issues. The standard reply I am told is that "the lens must have been dropped" followed by the estimate for repairs.
    Cheers, Dave
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    Re: Re-chipping old AF lenses

    I have this Sigma APO 400/5.6, came along with my Minolta film system. The optics is very bad and it has cataract like hazziness all over. I sent it back to Sigma and it was beyond any help.
    However, all my other Sigma lenses are able to be rechipped by Sigma for free. I just do not understand why there is a need to rechip this particular lens at a cost

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    Senior Member dhsimmonds's Avatar
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    Re: Re-chipping old AF lenses

    Quote Originally Posted by Mark K View Post
    I have this Sigma APO 400/5.6, came along with my Minolta film system. The optics is very bad and it has cataract like hazziness all over. I sent it back to Sigma and it was beyond any help.
    However, all my other Sigma lenses are able to be rechipped by Sigma for free. I just do not understand why there is a need to rechip this particular lens at a cost
    The article was for modifying the pre APO version of this lens, which apparently is very much lighter in weight. This is the attraction plus it's optical performance. I think that I would suffer the weight penalty and go for the APO......but I am not into this retro stuff very much, just thought it might interest any one here with an old lens collection!
    Cheers, Dave
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    Re: Re-chipping old AF lenses

    Quote Originally Posted by dhsimmonds View Post

    Greg - The older Sigmas were very well built with gunmetal barrels, black flock lined lens hoods etc so I am guessing that the gears were similarly made. However, I have also heard that the modern Sigma's have plastic gears which the high torque Alpha motors can easily strip.

    I have asked Sigma reps this question in the UK and they dodged the question referring me to their technical guru's. I notice that only selective Sigma lenses are fitted with the Sony mount, others don't. So I haven't bothered to ask the question

    At the moment I wouldn't take the risk myself of using Sigma lenses on the A900. Sigma are renowned for dodging quality after sales issues. The standard reply I am told is that "the lens must have been dropped" followed by the estimate for repairs.

    You're probably essentially correct, but I don't think it's correllated well to age. Hopefully the older, metal lenses have metal gears...in general.

    But I'm pretty certain that one of the three or four Sigma lenses I've been burdened with that was defective was a 400mm f/5.6. And it was allegedly fine before it was shipped to me! (I trust the seller in this case).

    It was a few years back, so I can't recall the specifics.

    So, given that (as noted above), the IQ is uncertain as well, I'd say it's not worth the risk. The non-APO versions especially.

    Ironically...it's the Sigma UK people that I've heard were actually HELPFUL. The US ones are useless...it's a bummer that the UK folks seem to have taken the same tack.

    Greg

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    Re: Re-chipping old AF lenses

    Quote Originally Posted by dhsimmonds View Post
    The article was for modifying the pre APO version of this lens, which apparently is very much lighter in weight. This is the attraction plus it's optical performance. I think that I would suffer the weight penalty and go for the APO......but I am not into this retro stuff very much, just thought it might interest any one here with an old lens collection!
    Interesting. I heard the exact opposite. I've used the non-APO and it was meager at best.

    The only Sigma lenses I'd recommend are the 70-210 2.8 (for under $400) and the old 24mm 2.8 (for under $60).

    Both are fairly robust...and a little noisy, but seem to perform well for their price. The 24mm actually beat out the KM version...but then, so did the 17-35mm.

    Greg

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