A convex lens behaves a lot like a concave mirror — far objects give small real images, and only up close does it act as a magnifying glass.
Real, inverted, diminished image forms between F₂ and 2F₂.
Just like with mirrors, only two rays are needed to locate an image through a convex lens: a ray parallel to the axis (bends through the focus on the far side), a ray through the near focus (emerges parallel to the axis), and a ray through the optical centre (goes straight through, unbent). Any two of these pinpoint the image.
For a convex lens, the image again depends heavily on object position. Object at infinity: a highly diminished, point-sized real, inverted image forms right at F₂. Object beyond 2F₁: a diminished real, inverted image forms between F₂ and 2F₂. Object exactly at 2F₁: real, inverted, same-size image at 2F₂. Object between F₁ and 2F₁: real, inverted, and magnified, beyond 2F₂.
At F₁, the emerging rays become parallel — no image forms. But bring the object between F₁ and the optical centre, and the lens flips into magnifying glass mode: the image becomes virtual, erect, and magnified, appearing on the same side as the object — exactly how a watchmaker's loupe or magnifying glass works.
Key exam points
Watch it explained
Image Formation by Convex Lens | Ray Diagram — Light, Class 10th · CBSE Class 10