Optical Image Stabilizer : Rated for up to four equivalent stops of shake correction.
Close Focus : 3.6' (1.1m) at all focal lengths.
Maximum Reproduction Ratio : 1:3.2 (0.31x).
Focal Length : 55-250mm.
On the APS-C cameras for which it is designed, it gives angles of view similar to what an 88-400mm lens would give on a 35mm or full-frame camera. See also Crop Factor.
Angle of View : 27.7º - 6.25º diagonal.
Maximum Aperture : f/4 - 5.6.
Lens Mount : Plastic.
Size : 2.6" (70mm) diameter x 4.3" (108mm) when set to 55mm.
Gets longer at longer focal length settings.
Weight : 13.785 oz. (390.85g) actual measured.
Rated 13.75 oz. (390g).
This Canon 55-250mm IS II is one of Canon's most popular lenses because it's super sharp, focuses very close, has a perfect telephoto zoom range, has Image Stabilization for sharp hand-held photos in dim light, and is small, light and inexpensive.
You can pay more to get a lens that works better while being rained-on or blasted in a sandstorm while being beaten around by a news photographer, or that works on expensive full-frame cameras, but even if you pay more for something like a 70-200mm f/4 L IS, you'll have a bigger lens to carry around, it won't be any sharper, and it won't have as broad a zoom range! There are many reasons this 55-250 is among Canon's best selling lenses.
Canon calls this the Canon Zoom Lens EF-S 55-250mm f/4-5.6 IS II.
EF: Electronic Focus. All modern Canon lenses focus with a motor in the lens.
-S: Only works on newer, small (APS-C) DSLRs.
IS: Image Stabilization, which means no tripod needed except at night. See Why IS Matters. Canon claims 4 stops.
II: Second version.