The zoom is a sliding zoom with a manual clamping ring, which no longer uses fixed at full zoom of 1300mm. The optics of a kink, in particular when a heavy camera is connected.
The focus does more bad than good to not at all. The rotating mechanism would, in my opinion, certainly tolerate twice the distance. So I would recommend to use the optics only for infinity or 5m (minimum focusing distance). In between, there will be more than frustig funny.
To paraphrase the words of a photographer: For the price you have to be happy that the lenses are really made of glass.
Who wants a similar zoom range with better quality should take a telescope with an adapter, or very, very profound, in his pocket.
Despite all the negatives you have to say that you can still make halfway decent photos so. Even a system transition from eg: Nikon to Canon does not represent a big problem as the lens itself has a T2 screw and can only be used with an adapter. Thus, the costs remain limited.
