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Thanks everyone!Here's another one from the Cahokia Mounds state park. Low fog during an autumn sunset.Statistics: Posted by smulnik — Sun Jan 28, 2024 8:18 pm
Thanks guys!A frozen Horseshoe lake. The lake is only about 6 feet deep and freezes quickly. It's just 10 minutes from my house, so it's one of my quick go-to places if it looks there is going to be a nice sunrise or sunset.SigSunrise SunsetStatistics: Posted by smulnik — Sun Jan 28, 2024 7:51 pm
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I have a similar lens. Where the aperture control does not work on my Canon 1000d. Don’t know if it is exactly the same.
I still do not understand how this could work. How can the camera change aperture without having any electrical connection to the lens.
Johannes
The Canon lens is entirely different. The Minolta/Sony aperture control is purely mechanical and does not depend on any electronic feedback (hard though that may be to understand). The body moves a lever, which has a certain amount of travel for every 1/3rd stop down from wide open. The lens transmits its maximum aperture and the permissable variation to the body, and that is all. The body then moves the actuator the appropriate amount. The chip for the Minolta AF version just enables AF. Without the chip the lens still has a working aperture system.
Hi:
I bought a Tokina AF SD 70-210 F4-5.6, Minolta Mount A, to use with my Sony A200. It’s only work Manual, focus and aperture-shutter. When I select Auto or Program, the LCD warns that “no lens attached, shutter lock” I wrote several emails to James Lao (and he received it) but no answer. Does anybody can tell me if this guy is still working? Any other idea to solve the issue?
Thanks a lot
Jaime
Lao is still around but he can not re-chip a Tokina. A good way to deal with the problem would be to find a damaged 70-120mm of a similar specification, but made by Minolta, and remove the chip – fit it in the Tokina
I’m sorry but I do not understand. Shouldn’t you solder the cable from the old chipboard onto the new chipboard in order to have functioning AF and aperture control?
The old chip has no further use. There are no electrical functions in the lens. It’s all mechanical. The chip just provides identity, the camera knows where the lens is focused by doing calibration – that’s when you switch on (and off) it sets the focus to infinity before doing AF – it’s telling the camera what lens is fitted, then the camera gets the ‘reading’ at infinity, and uses the number of rotations of the drive to work out what’s happening. Of course with modern SSM (focus motor in lens) designs there’s a lot more feedback, same goes for eight-pin contacts and chips (xi and D lenses). But the original 5-pin chip like this does not actually get any data from anything happening in the lens.
Hi there. Great post. Do you have any idea which chip to order from James’ page? I really need to get my 400mm rechipped, but James’ page is a little impenetrable for mere mortals like myself!
Please Sigma UK, can I have that lens I sent to you that you couldn’t rechip for me back now please? – Actually having seen the results optically I don’t think I would bother 😉 I’ll stick to the 70-300G and crop.
Current web address for ordering chip:
//www.eadpt.com/eadpen.htm
same as iamike-
this is great info, is there a current contact for Lao? Google doesn’t seem to connect any James Laos with a product like this.
Hi David,
Thanks for the information. Could you give me Lao’s email or other contacts? I couldn’t open the link.
I have a similar lens. Where the aperture control does not work on my Canon 1000d. Don’t know if it is exactly the same.
I still do not understand how this could work. How can the camera change aperture without having any electrical connection to the lens.
Johannes
The Canon lens is entirely different. The Minolta/Sony aperture control is purely mechanical and does not depend on any electronic feedback (hard though that may be to understand). The body moves a lever, which has a certain amount of travel for every 1/3rd stop down from wide open. The lens transmits its maximum aperture and the permissable variation to the body, and that is all. The body then moves the actuator the appropriate amount. The chip for the Minolta AF version just enables AF. Without the chip the lens still has a working aperture system.
Hi:
I bought a Tokina AF SD 70-210 F4-5.6, Minolta Mount A, to use with my Sony A200. It’s only work Manual, focus and aperture-shutter. When I select Auto or Program, the LCD warns that “no lens attached, shutter lock” I wrote several emails to James Lao (and he received it) but no answer. Does anybody can tell me if this guy is still working? Any other idea to solve the issue?
Thanks a lot
Jaime
Lao is still around but he can not re-chip a Tokina. A good way to deal with the problem would be to find a damaged 70-120mm of a similar specification, but made by Minolta, and remove the chip – fit it in the Tokina
David
I’m sorry but I do not understand. Shouldn’t you solder the cable from the old chipboard onto the new chipboard in order to have functioning AF and aperture control?
The old chip has no further use. There are no electrical functions in the lens. It’s all mechanical. The chip just provides identity, the camera knows where the lens is focused by doing calibration – that’s when you switch on (and off) it sets the focus to infinity before doing AF – it’s telling the camera what lens is fitted, then the camera gets the ‘reading’ at infinity, and uses the number of rotations of the drive to work out what’s happening. Of course with modern SSM (focus motor in lens) designs there’s a lot more feedback, same goes for eight-pin contacts and chips (xi and D lenses). But the original 5-pin chip like this does not actually get any data from anything happening in the lens.
David
Hi there. Great post. Do you have any idea which chip to order from James’ page? I really need to get my 400mm rechipped, but James’ page is a little impenetrable for mere mortals like myself!
Tom
I have now updated the link again – the new one I found failed shortly after putting it in place. Also, I have corrected a typo – James Lao not Loa!
David
The URL always worked for me and was redirected by the owner to a new domain. I have now changed the URL to the new domain.
David
Thanks David.
Do you have a working link to James Lao?
The link in your text does not work.
Regards
John
Thanks for the report on the lens David.
Please Sigma UK, can I have that lens I sent to you that you couldn’t rechip for me back now please? – Actually having seen the results optically I don’t think I would bother 😉 I’ll stick to the 70-300G and crop.