The Swarovski 25-50x zoom eyepiece is a more recent addition to the ATS/STS range, and offers an excellent wide field of view throughout the magnification range. At the 25x setting you get a bright, wide field, ideal for low light use or scanning large areas of habitat. With a quick turn of the smooth zoom mechanism to the 50x setting, the sharpness and field of view remain very impressive, but at the same time apparently bringing your subject much closer with glorious detail. The enhanced field of view compared to the 20-60x eyepiece for many more than makes up for the slightly lower maximum magnification. The 17mm eye relief enables glasses wearers to comfortably see the full field of view.