The plastic bag trick works ok in light rain with no wind, but if its raining hard or you are in high wind I wouldn't recomend taking the chance. The storm-jackets are a good item for the price ($30-$60)and they are much safer. Although I have heard of troubles with it sliding back on the lens if you are using a very long lens. But if you get the larger one and don't use it with a very long lens it shouldn't be a problem.