Lavinia asked if I had used a telescope to photograph the moon last night. Lavinia never lets me down on being observant and asking questions when something seems different like a whole lot of detail in the moon photo. As I answered her, I did not use a telescope, I used a 400mm lens that is equivalent to a 640mm lens on my Canon 7D Mark II body. I have been considering getting a long telephoto lens for quite some time.
I was originally looking at the Canon 100-400mm lens, which is one of Canon’s best telephoto zoom lenses for mere mortal photographers, such as myself. However, the 100-400mm lens is ƒ/4.5 to ƒ/5.6, which is a little slow for as much low light photography as I do. I really needed a faster telephoto lens. I seriously considered both the Canon 400mm ƒ/2.8 and the Canon 300mm ƒ/2.8 lenses. The problem with those lenses for me is their weight. The Canon 400mm ƒ/2.8 weighs in at 12 pounds, and the 300mm ƒ/2.8 weighs 6 pounds, 1/2 the weight of the 400mm ƒ/2.8, but still a heavy lens.
I ended up compromising on speed for lighter weight and bought a 400mm ƒ/4.0 DO lens with Refractive Optics, which enables Canon to put a 400mm ƒ/4.0 lens in the same body as the 300mm ƒ/2.8 lens, shaving 2 pounds off the weight in the process. At 4 pounds, the 400mm ƒ/4.0 DO is easy to handle, and fast enough to get decent images hand held in low light. In the photos of the owls below, we could only see outlines of the owls with our bare eyes like in the first photo, but not nearly as close up. The new lens is able to focus on the owls in relative darkness, through the branches and get an amazing amount of detail.