TL;DR: you need tubes that have electrical contacts and aperture control linkage pass-through to control your "G" lens's aperture.

Nikon lenses that are not the "E" (electronic aperture) type have mechanically-actuated apertures. The lens has a spring-loaded aperture control lever that is controlled by a matching aperture control lever in the camera body.

Nikon "G" lenses, being a non-E lens, require mechanical aperture control. The "G" designates lenses without aperture control rings. Thus, the only way to control the aperture in "G" lenses is by the camera body, or some device that mounts on the lens and mechanically moves the aperture lever, such as the Nikon BR-6 auto diaphragm ring, or the Photodiox Nikon G Aperture Control Enabler.

(Note: both of the mentioned adapters are for reverse-mounted lenses, with the lens mount being exposed towards the subject, not for using inline between lens and body).

There are a few brands of extension tubes available with electrical contacts that pass signals between the body and the lens. The electrical contacts are necessary because even the aperture linkage is mechanical, the camera will not control the aperture if it doesn't know there is a lens attached. The identification of the lens is through the electrical contacts.

Thus, in order to control the aperture of "G" lenses mounted on extension tubes, the tubes must have electrical contacts to pass signals between the camera body and lens.

Below is a non-exhaustive list of tubes currently available that will work with "G" lenses (links go to brand websites, not retailers):

• Vello Auto Extension Tube Set for Nikon
• Kenko DG Teleplus Extension Tube Set
• Xit Pro Series Extension Tube Set for Nikon
• Meike MK-N-AF-A Metal Auto Focus AF Macro Extension Tube Set for Nikon Camera

There are several other brands that don't have their own websites, that can be found on Amazon, B&H, Adorama, etc.

Disclosure: I own and use the Xit tubes. They work fine, and I have not had any problems with them.