This lens looks good at first, but has some serious issues. Definitely not what one would expect from Vivitar. Image quality is rather poor: soft at f5,6 and slightly better at f8, acceptable sharpness at f11. Chromatic Aberrations (CA) are terrible: awful red fringing on almost all pictures (see samples), it is even visible in the "bokeh". The lens seems to have some kind of coating, but it is not very effective on the CA issues. I did not notice any haze or lack of contrast, so in that aspect the lens is fine. Handling is easier than one would think. The lens is not that long and can be hand held, although there is an adjustable tripod collar. Focusing is smooth and can be done pretty fast, after some practice. I would not recommend this lens unless you really need a telephoto and if you don't mind clearing the CA in post-processing. I'd say it would be worth maximum 25 euros, any higher than that and you can probably find something better, but for under 25 euros, it's acceptable. (I paid 10 euros)

 

(by Tom De Nies) 

Very sharp, lens with nice "bokeh". Lens design is very simple. Focusing is super fast almost fast as an AF lens. Lens barrel made from aluminium so light weight compare with other 400mm lenses. Easy to split  for transporting , much easier to handle than others. Before I made any test shoots I was worry about how I able to handle hand shaking, because I use 2x crop camera Olympus-E1. Effective focal length 800mm on this camera first usage was pleasant surprise, sharp at wide open! I could make many great shoots from hand without any tripod. I bought this lens with fungus. I cleaned my self, this lens was the most logical construction in my experience. I didn't find any weakness I love this lens ! SUPERB!

This lens has a little bit of everything, wide-angle, macro and portrait lens. Quality is good to average, certainly not top at each field area but it performs quite well. If you have no space to bring quality prime lenses this lens would be a good choice. Colour rendering is very nice, a well built lens both mechanically and optically.

A sharp lens, real Nikkor.Colour rendering is very nice, well built lens both mechanically and optically.First class quality even if  I found one weak point: "bokeh" is nothing  compare with other 135mm lenses like Pentacon 135mm, Carl Zeiss Jena Sonnar 135mm or Konica Hexanon 135mm.