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Photo

D40 with Sigma 70-210 f2.8 APO


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5 replies to this topic

#1
bobthebuilder

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This has probably been asked before but I can't find any similar questions so please excuse me if it's has been asked a million times.

 

I have recently inherited a Sigma 70-210 f.28 AF APO lens but it won't auto focus with my D40, is there a problem with the lens or is it just incompatible with the D40 AF system? The lens is in pretty poor shape so I'm wonder if a service would help it.

 

Are there other Nikon cameras with which it would auto focus?

 

Thanks for any insight.

 

Cheers,

Bob



#2
Merco_61

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If it is a lens without a built-in focus motor, the AF won't work on the D40 as the D40 has the crippled F-mount without a focus motor in the body. The lens might work with a D7xxx, D70, D50, three-digit or single-digit body unless there is a firmware problem. Sigma have to reverse-engineer the communications protocol for Nikon F-mount and have been caught out a couple of times when Nikon have activated new functions in new bodies. Older Sigmas don't have a flashable CPU, so they need to be sent in and an upgraded CPU soldered in place when this happens.



#3
bobthebuilder

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Thanks for the reply. 

 

According to this it has an in body AF drive, so I guess it's an issue with the reverse engineered comm protocol. I'll see if I can get any answers from Sigma to see if it's possible to upgrade the CPU or whether it's even worth it.

 

Bob.



#4
Merco_61

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In body AF means that it needs a focus motor in the camera body that the D40 doesn't have. Lenses that are compatible with the D40 have In Lens AF.

 

Besides which, the site you linked to is a Sony/Minolta site and the specifications are for the A-mount version.



#5
bobthebuilder

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Besides which, the site you linked to is a Sony/Minolta site and the specifications are for the A-mount version.

 

Oops! I looked at so many sites looking for the info about the motor I glossed over other important information.

 

Guess I won't need to bother contacting Sigma.Thanks for the follow-up.

 

Bob



#6
Merco_61

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Here is a partial shot of two lenses.

PES_2017-11-05_19-57-47_105mm_.JPG

The one to the right has an in-lens motor, the one on the left is screw-drive.

The AF driver is at 5 o'clock on the left lens.

 

The driver mates to the driver on the body as seen in the second photo.

PES_2017-11-05_19-59-26_105mm_.JPG

 

If the driver on the lens is there, that lens doesn't have a focus motor and won't AF on your D40. It is as easy as that to check, once you know what to look for.