There is a wide variety of opinions on the proper amount of vermouth to put in a martini. I believe the original ratio of gin to vermouth was something approaching 1:1, but the trend in recent years has been towards smaller amounts of vermouth, with some people (myself included) preferring a drink that might better be described as "cold gin in a glass". With an olive.

I've seen more than one bartender rinse the inside of a martini glass with vermouth, dump it out, then shake the gin with ice and pour it into the glass. I tend to favor this technique.

It's probably best to give the bartender some direction as to the amount of vermouth you want, since there seems to be no real standard.