Therefore, maximum power of optical microscopes are thought to be 1000x to 1500x. There are several indications on an eye-piece lens. I recommend using 10x eye-piece. Higher power eye-piece is difficult to look through and has very narrow field. And also note that higher power eye-piece does not make the resolution higher.
Resolution depends on the quality of the objective lens.
If you use high power eye-piece on a image made by low resolution objective lens, blur will just be enlarged and will see nothing. Field Virtual image of objective lens will be made just in front of the eye-piece. Eye-piece is designed to enlarge this virtual image. Normal eye-piece has field of 10 to 12. Microscopes designed for super wide field has bigger tube.