Thanks useful information: 
I may not be helping, but a bit of research by yourself, prior to buying would have alleviated this thread entirely. A quick google would have found that ALL extension tubes are just metal or plastic round cylinders, no electronics at all.
You have to get the right ones for your brand (cause they need to fit the lens mounting system), then you need to shoot all your photos in manual, including manually focusing. As long as you brought the ones for your camera brand, they will work.
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