You don't need slow motion camera, it's enough with most normal catch the worst offenders in the store if they have those led display sets where you can see the

You don't need slow motion camera, it's enough with most normal catch the worst offenders in the store if they have those led display sets where you can see the lightbulb lit. Just shove the camera real close to the lightbulb and watch the stripes. If no stripes, put it even closer (almost touching) and if it's still ok, buy it :-)