How to tell which fisheye lens has a wider angle?

For example i was looking on ebay at 52mm lens for my nikon and next to some it may say like x brand.18x fisheye lens. So what i want to know is would a.18x lens have a wider angle then a.3x?

The seemingly random use of "number-X" and "number-MM" designations on lenses can be confusing, but it boils down to 2 things: simple math, and whether it's a "prime lens" or an "adapter".

Your Nikon 52mm lens spec is telling you that it's a prime lens (fixed focal length in millimeters; and a true lens, not an adapter). Then to make that 52mm "normal" lens into a wide-angle, you'd need an adapter with a multiplier (the "X-factor" or "times-factor") of less-than one.

Using simple math to multiply the.18x or the.3x with your 52mm focal length would, respectively, give you 9.4mm and 15.6mm focal lengths (when the adapter is screwed onto the 52mm).

The smaller the "millimeters" (focal length), the wider-angle the resulting lens is.So.18x adapter is wider than a.3x one. (An adapter with a number greater than "1", e.g., "2.5x", would be a teleconverter or "telephoto adapter" for closeups from a distance. Same math applies.)

Since you're a skateboarder, from looking at your other Y! A Questions, you've probably heard the terms "death lens" and "baby death lens" which are just nicknames for regular and small wide-angle adapters, due to the injury hazards of getting too close to the action with fisheye lenses.

hope this helps,
--Dennis C.