Meh, I want to see a comparsion using equivalent focal lengths 210 and 200mm is fine.. but the framing must be exactly the same (subject takes up the same percentage on the sensor). Both images downsampled (never upsampled) to fit here on the site. Any crops (as long as there's no upsampling ) should be fine... ex: 100% on the sx50 and 55% on the 5D mark III (for equivalent sized images.)
other than that it's apples and oranges.
Well, they're both fruits; OP is talking about reach/resolution vs cost and its obvious SX50 comes on top. Comparing them in the exact same frame doesnt make any sense.
Of course it's apples and oranges... an apple makes a better apple than an orange.... and vice versa.
Setup 1: 5D3 and 400F5.6 Setup 2: SX50
Take a picture of Ospreys on the nest.... middle of the day with good lighting, #2 is best, poor lighting, #1 is best. Osprey is sitting still, #2 is best... while flying it's #1. Zoomed all the way out, #2 is best, closer, it's #1. #2 is a LOT more portable and much less expensive. Weathersealing..
There are no absolutes. No camera, no lens, no technology does it better than everything else in every situation. A camera is a tool and we need to learn what tool works best for what purpose under which situation.
For what it is, the SX-50 is fantastic. It is a wonderful tool for capturing images of far away subjects that are past the reach of an affordable DSLR lens when the lighting is good.... but it will never replace a DSLR as an all-round camera, particularly in poor lighting or hard to focus situations.