How does WarmCards compare to ExpoDisc?
First of all, ExpoDiscs must be mounted on the front of your lens. So you’ll need different sizes or buy adapter rings for every lens you own. Second, ExpoDiscs are designed to only give you an ordinary neutral white balance — while WarmCards are designed to give you a warmer or cooler white balance. Although there is new version of ExpoDisc called “portrait” that provides some warming, once again, it won’t fit all lenses, and it only offers one shade. On the other hand, WarmCards work with all lenses and every kit includes 8 different shades to choose from. Third, the biggest problem with ExpoDisc is one that you might overlook until you’ve used it. Once an ExpoDisc is mounted on the lens, it can only measure the light that happens to be hitting the front of the lens. Think about that. Is the lighting at the camera position the same light that is hitting your subject? Not always. There are many situations where setting a white balance based on the light striking the camera lens is no
