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I need a trick to stop down a Sigma Lens.


New Member
Hello Everyone,

I own two Sigma lenses with Sigma mounts which I would like to stop down but I do NOT have a Sigma body. Are there any tricks to do this ?

I modified a Pentax to Eos adapter so I can attach them to my Canon but it would be much nicer to shoot stopped down.

I tried "zapping" the electrical contacts with some wires and a 4DC and 7.5 DC adapter and nothing happened ... well at least they didn't catch on fire ! LOLOL

So any suggestions would be most welcome !


Well-Known Member
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Your only option is to convert them to EF mount. First you need a doner EF mount lens or two and you will need to unscrew and remove its/their EF mounting plate/s. You will notice that the connector block is attached to a ribbon cable. Next unscrew and remove the SA mounting plate and you will notice a similar ribbon cable soldered onto its connector block. Unsolder the ribbon cable from each lens and then solder the EF connector block onto the SA ribbon cable. Solder the wires the same way around as the pin connections are indentical. Then fit the EF plate onto the SA lens. You will probably need to drill and countersink some new securing holes in the EF plate to line up with the ones in the rear of the SA lens, but this is easy if you use the SA plate you've removed as a drill template. Best of luck. BTW if you succeed and you have no further use for them I'll happily take those SA mounting plates off your hands.


New Member

Thanks for your reply ... unfortunately I do not have any EF plates ... but if Santa or maybe Alice brings me some ill send the Sigma mounting plates your way. Maybe Ill try and find a Sigma body owner ... here in Montreal ... where I live and do the "stopdown" preview trick and keep the lenses at F8.