Good product. Be careful. It is a tes tfor the best tripod. I added a weight to the front end to get it to balance better with my D90 attached. Only had it 2 days and have shot pictures from f5.6--f16 with good results. Shot a snow capped mountain from about 10 miles this a.m. @1200mm and it filled the viewfinder.
More than the product, I would give five stars to Overstock's fast processing, low international posting rates (they sent it nicely packed via FedEx for next to nothing); and prompt delivery notifcation. The product, well, I am still trying to look for ways and means to make it work. It is good, but its chief drawback is that it is a manual lens in an automatic world. My Nikon D90 has to struggle, alongside me, to figure out how to take the best pictures with it. By the time the settings (extremely complex, unless you are a professional photographer with almost 10+ years of working) come out right, the subject has usually moved. Apart from that, life is good if you eat right, love others, exercise regularly and thank the Lord.
I can't give this lens a good review. The locking ring is so tight at the 650mm mark but the lens will spin in place. When the ring is unlocked the the adjustment part of the lens will not tighten up at all and if I move it to the 1300mm mark it just flops up and down and side to side. If I could have returned this item I would have.