i own a Sony DSC H1 camera.. i want to by a teleconversion lens for the same... shopkeeper suggested to buy 58mm (2x) teleconversion lens... now what does this 58mm signify?? how can i choose a good one at an economical rates?? please help 58mm is the diameter of the front of your video camera lens. It tells you what thread size (in this case 58mm) lens accessories to buy for your camera (i.e. filters, teleconverters). It has no bearing on the type of product you buy, so long as it fits the thread. the answer above is correct, it is how big of a size of lens. Best bet for a good lens is to buy a lens of the same maker as your camera. The better the glass is in the lens the higher the price so you have to decide where your budget fits vs. your wants. | 