"Edmund Hillary after his successful attempt on Everest with Alfred Gregory and Tom Bourdillon at advanced base camp" Alfred Gregory was the 1953 Everest expedition official photographer, the Rolleiflex is hanging from his neck; photograph taken by George Band. (Very low resolution image from the RGS, higher resolutions are for sale, click on thumbnail).
"Tom Stobart with cine camera and Alfred Gregory with camera preparing to take images of the Sherpas who had reach high altitude", photograph taken by George Lowe on 30 May 1953 during the British 1953 Everest expedition. The red arrow indicates the Gregory's Rolleiflex camera used for the expedition (Very low image resolution from the Royal Geographical Society, higher resolutions are for sale, click on the thumbnail) "...I also took a twin-lens Rolleiflex which I used for black and white.Despite being more bulky than the Contax and Retina it was extremely easy to use and with its superb Zeiss lens it was capable of producing pictures of exquisite quality. I took it as the South Col and the final results made the extras effort well worth while. When in recent years these three cameras were stolen I felt I had lost a very real part of history..." (Alfred Gregory, 1953 Everest expedition official photographer).
