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Extension tubes provide (for some people) an attractive way of adding a Macro capability to their camera set up. Extension tubes are available for almost every SLR body, can be attached to different lenses for different effects, and are much, much less expensive than dedicated macro lenses. I know that Canon and Nikon both make extension tubes for their cameras and I know that Kenko makes extension tubes for almost every SLR brand. The Nikon School plugged extension tubes as a reasonable alternative to macro lenses so I went that way. I have been learning about the peculiarities and limitations of extension tubes for several days now and wanted to share some of the things I've learned.

the subject is that the cheap extension tubes have not got the needed linkages to enable metering and aperture adjustment with your contemporary lenses, no longer to show autofocus. i take advantage of M42 tubes and an previous 50mm Pentacon lens for closeup artwork on my DSLR - yet this makes use of a glassless adapter and my digital camera can meter stopped down (Av and M modes) - the D3200 won't be able to. there is not any low priced thank you to do what you like and shield TTL metering with your contemporary equipment.

Guessing here...

You bought a really cheap tube? Those are full manual. You put a g-type lens on it. That means that the aperture is fully closed. Cheap tubes work best with lenses with an aperture ring and even then you woll have to focus manually.