Hi! I have a question about 3 items, produced by 3rd parties (of course all Nikon mount). Could anybody comment following items: Vivitar 70-210/4.5 AI Star-D 28/2.8 AI Star-D 2X tele converter What about optical abilities, color rendition etc. I haven't met anything about these particular pieces anywhere. Are they SO bad? I have in those focal distances no comparison possibilities so any hint is welcome! Cheerio! Peeter
