|Canon EF 800mm f/5.6L Super Telephoto lens|
Canon pioneered the development of Diffractive Optics lens in the late 1990s and introduced the first Super Telephoto EF 400mm f/4 DO IS lens in 2001. It was the first 400mm lens with a combination of 'light weight' and speed, all packed into a professional piece of glass.
I bought the lens in 2008 and it quickly became a staple in my equipment bag for wildlife photography. The drawback was, the lens did not have the highest image quality in Canon's Super Telephoto lineup, especially when a teleconverter is added but I was willing to accept the compromise once all things are considered.
Then in September 2014, the EF 400mm f/4 DO IS II was announced. This time, I jumped at the chance of getting the Version II after almost 15 years of enhanced development. I have advocated the use of Diffractive Optics for years and now even Nikon has seen the light and announced their first 300mm DO lens in January 2015, called Phase Fresnel, and patented another zoom lens design.
Canon's longest Super Telephoto lens, the EF 800mm f/5.6L is aging and sorely needs a replacement. The company is indeed considering replacing the lens with a Series II, Diffractive Optics model. I cannot be happier, since this technology has now been proven and will give Canon a definitive edge over its competitor. I will definitely be interested in acquiring the EF 600mm or EF 800mm f/4 DO IS when it comes out.