Prince William has been pictured wearing spectacles as he focused on an Army firepower demonstration.
The Prince attended the display at Warminster on Salisbury Plain, Wiltshire, with a group of fellow cadets from Sandhurst military academy.
Among the weaponry in action were Challenger and Warrior tanks, Apache helicopters and Jaguar aircraft, as well as artillery and rockets.
Clarence House confirmed the Prince does wear glasses from time to time.
Battle group formation
The three-day display forms part of the military education of members of Sandhurst and the Army's Staff College.
About 1,500 forces personnel attend each day to see individual weapons, support weapons, offensive support, aircraft and engineering assistance put through their paces.
A Ministry of Defence (MoD) spokesman said: "It's a routine display of Army equipment technology primarily for the Staff College, which is for Major and Lieutenant Colonel level, and it's to demonstrate the capabilities and equipment found in a battle group formation.
"For a large number of people there it's for their professional development and understanding. For others it's seeing equipment in action."
William is set to follow his brother Harry into the Household Cavalry's Blues and Royals, with the aim of becoming a troop leader in an armoured reconnaissance unit.
He is due to start a six-month course at Bovington Camp in Dorset upon passing out at Sandhurst in December.
The Prince passed his Regular Commissions Board (RCB) to gain entry to the Royal Military Academy in October 2005 and started his training at the college in January.