Originally posted by elliott If it is cheap enough, it is worth a shot. I have a feeling it might have been made by Samyang, who are doing some very good stuff lately, but their older glass isn't that great.
One that is a pretty safe bet is a 400mm f6.3 that was sold under many names. It was made by Tokina and has the interchangeable T-mount, so finding one with a dead mount like Minolta MD or Canon FD on it could be very cheap. I've seen it under Tokina, Vivitar, Spiratone, Bushnell, Soligor, Lentar, Asanuma and probably a dozen more.
Thanks a bunch, that was very useful information. I have been looking at the spiratone 400mm 6.3 and soligor and recently discovered they were the same (I had been led to believe they were a bit better than some). I was not aware that they were made by tokina though, and was not aware that they were the same as the other brands you mentioned. I had already decided to try and get the spiratone (they seem to sell for less than the soligor despite being the same lens). Knowing the other brands are the same will make shopping much easier.
Thanks again.