Summary: Well I paired with my nikkor 55-300 lens on my nikon d5300 and it constantly searches for focus, bypassing the focus constantly, never finds it so since I bought it in hopes to use it for surf photography, manual focus won't do it for me so I will have to return it.
Summary: Pretty nice teleconverter. Budget friendly and well built. My only complaint is that it is not the same as in the picture. The one I received has a different rubber grip. Not really a huge deal but I don't like the new style as much.
Excerpt: Since Nikons extenders won't work with my lenses I tried this one. It's well built, electronically connected and is very sharp. Auto focus doesn't work at full zoom, 300mm, but I didn't expect that given the write up on B&H's always excellent website. Initial testing shows it's way sharper than my Vivitar mirror lens. Pictures at 300 mm, Nikon 70-300 fully extended and at150 mm+2x extender are visually identical.