Compared to other fresh fruit, raspberries are intensely flavorful and very tart, so to make ice cream you need less fruit and more sugar.
Although I find that 1 cup of sugar works well from my tastebuds.
Toss the raspberries, 0.75 cup sugar, and the lemon juice together in a bowl. Cover and refrigerate for 2 hours, stirring every 30 minutes.
Whisk the eggs in a mixing bowl until light and fluffy, 1-2 minutes.
Whisk in the remaining 0.75 cup sugar, a little at a time, then continue whisking until completely blended, about 1 minute more. Pour in the heavy cream and milk and whisk to blend. Drain the juice from the raspberries into the cream mixture and blend. Mash the raspberries with a fork until pureed and stir them into the cream mixture.
Transfer the mixture to an ice cream maker and freeze following the manufacturer's instructions. Makes 1 very generous quart. You may need to adjust the recipe down so it'll fit into your ice cream maker.
NOTE: If you prefer a chunkier raspberry ice cream, return the raspberries to the refrigerator after pouring off the juice. After the ice cream stiffens, about 2 minutes before it is done, add the whole raspberries.