Where can I buy magnifying glasses or just lens of various sizes? Any online shop or actual shop (Lahore) that sells optical instruments?
What do you need it for? Telescope?
yes. I found some magnifying glasses in book stores but they dont even have magification written on them properly.
Scientific stores or any optician should be the place to buy lenses.
Try bookstores ... saw several at Saeed Book Bank, Islamabad and presume bookstores in Lahore would also carry them. Can also get them online from AliExpress.