With this zoom eyepiece the magnification can be adjusted smoothly. It is very convinient to use a zoom eyepiece but might be also cheaper than buying 3 or more separate fixed focus eyepieces. Can be used for both astronomical work and daytime observations. The zoom eyepiece contains 8 lenses, fits to 1.25" focusers and has standard filter threads. The field of view is 40 degrees (measured) at 24 mm and 57 degrees at 8 mm. Image distortion is present but almost unnoticeable even at f/5. A long eye relief eyepiece that can be used with glasses as well.