If the focal length of objective lens is increased then magnifying power of

Magnifying power of a microscope, m=LfoDfewhere f0 and fe are the focal lengths of the objective and eyepiece respectively and L is the distance between their focal points and D is the least distance of distinct vision. If f0 increases, then m will decrease.  Magnifying power of a telescope, m=f0fewhere f0 and fe are the focal lengths of the objective and eyepiece respectively. If f0 increases, then m will increase.