Originally posted by jpzk I am really trying to figure this "debate" out between the Bigma and the BigMos (as they often call it) vs. the 150-500.
I think this will be hard to do, there are a lot of variables.
First when someone does a review of a 50mm lens you assume they are competent to take a picture with it. But with a 500mm there is a learning curve, it is not just point the camera and shoot. It requires real skill, proper stance, proper breathing, proper conditions, good light and low wind, low haze in the atmosphere, proper tripod and head if using one.
Second you are comparing 4 different lenses, which may have had updates or changes over the years that were not announced so different people may be talking about slightly different models.
Third Sigma has a reputation for a lot of sample variation in their lenses, so one reviewer's outstanding lens is just so-so with another lens.
And last you have camera/lens tuning, were the tested lenses AF tuned? Were the cameras used even capable of AF tuning?
I would love to see a controlled test, on the same camera, in the same conditions. But without that I think the reviews are even more unreliable for this type of lens than they are in general because of the inherent difficulty in getting a good image from this focal length.