REVISED (ADDITIONAL PHOTOS)
Several days ago I posted some photographs of Abraham Lincoln, including an early daguerreotype (taken when he was 31 or 32 years old) that looks entirely unlike the image of Lincoln we carry in our minds. That led me to remember the collection of presidents' images at the Smithsonian Institution's National Portrait Gallery in Washington, D.C. (The Portrait Gallery is closed for major renovations but much of the collection is available for viewing online.) Here are two priceless photographs from the Portrait Gallery's Hall of Presidents:
Daguerreotype of John Quincy Adams (1767-1848, president 1825-29), made in 1843 when Adams was 76 years old.
Daguerreotype of Martin Van Buren (1782-1862, president 1837-41), made ca. 1856 when Van Buren was about 74 years old.
Daguerreotype of Zachary Taylor (1784-1850, president 1849-50), with his aide and future son-in-law William S. Bliss, made ca. 1847 when Taylor was about 63 years old.
There's a lot more from Presidential Hall here.