As a person that has taken wildlife photography for a number of years, I would never recommend a beginner start out with a mirror, they, because they are so light, lead to very bad technique, besides lacking in the quality department, if I were to ever use another mirror it would be a version of them that is called the "Solid Cat" mirror lens, then you get away with out the problems associated with a normal mirror lens, but that said, the 500mm f/8 presets are a far better choice, and often times I see the old 800mm f/8 lenses on ebay that go for very reasonable prices, I picked one up for $250 and it is actually very good quality, but you have to use stop down metering and if you don't have a good tripod, forget it, just won't work.