Lightly toast pecans in a shallow baking pan in middle of oven until fragrant but not darker, about 5 minutes, then cool. Leave oven on.
Cook 1/2 cup sugar in a dry 2-quart heavy saucepan over moderate heat, undisturbed, until it begins to melt. Continue to cook, stirring occasionally with a fork (to help sugar melt evenly), until sugar is melted into a deep golden caramel. Tilt pan and carefully add corn syrup (caramel will harden and steam vigorously). Cook over moderately low heat, stirring, until caramel is dissolved.
Remove pan from heat and add butter, stirring until melted, then cool caramel until it stops bubbling. Whisk together eggs, salt, vanilla, and remaining 1/4 cup sugar, then add caramel in a stream, whisking constantly. 3Spread pecans and cranberries evenly in tart shell and pour caramel over them, tapping pecans and cranberries down to coat thoroughly. Bake tart in middle of oven until filling is set, 30 to 35 minutes. Cool completely in pan on a rack before removing rim of pan.