Yup - I've got that lens too and I never use it - it flares horribly, you need to use it with a mattebox and even then I'm not sure if you'll be able to kill off all the flare (wide open).
These flares are lovely (although I can understand you may not want them in some situations). And this is a great scarce lens overall with warm color, a long focus throw and really close focusing, almost macro.
I had one for a while, and it's not too bad if you use a decent lens hood. I used one of the metal screw-on hoods - on a micro 4/3 camera I used one intended for tele lenses, and suffered no vignetting.
52mm fader nd + 49-52 step up ring + vivitar 28mm lens.... too much flare. but other options are more expensive. a lot more. i gotta save money so that i will have enough firepower to upgrade the body. GH2, GH3, etc.
i ended up ordering $3.99 collapsible rubber 3-in-1 hood with a free cap. hopefully that mitigates the issue.
I figured that if I suffered from vignetting, it would be easy to grind down the end of the hood, but it wasn't necessary. The one I bought allows a generic 52mm lens cap to be used on the end, which is handy.