Some aspects to consider when buying a wide angle lens include:
Image Stabilization/Vibration Reduction – You don’t need to worry about this as much as you would when buying a different sort of camera lens since these lenses shoot at a very wide angle, the chances of image blur becomes less significant for handheld shooting. However, if you plan to take photos in low light conditions then a fast lens would come in handy.
Crop Sensor or Full Frame Sensor – As their names suggest, full frame sensors allow you the maximum wide angle possible, whereas crop sensors bring the “cropping factor” into play. For example, a 10mm wide angle lens would give you the complete 10mm with a full frame sensor, whereas a crop sensor would provide around 15mm. If all this seems confusing to you, fear not. For most photographers, either sensor/lens will suffice.
Fish eye lenses are a further advanced version of wide angle lenses and are named after the distortion of field of view they provide - similar to fish eyes! Though these camera lenses provide wonderful looking photos, ideally a photographer should first familiarise themselves with wide angle lenses in general.
(Photo by Il conte di Luna, click on images to enlarge)

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