A candle tall is placed to the left of a thin convex lens with focal length . What is the height and orientation of the image created?

The focal length of a thin convex lens is . A candle is placed to the left of the lens. Approximately where is the image of the candle?

Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at ?