Opinion: Best form of SR for telephoto shooting.

I recently added a Tamron 55BB mirror lens to my bag for use with my K5.  I am amazed at the handheld results I can get with the K-5's SR and the Tamron mirror.  Normally 500mm handheld is virtually out of the question as even the big 500mm glass with OS (read... big money) is frankly too cumbersome to handle and shoot without a tripod.

I was so thrilled with the Tamron making a walk-around 500mm a reality that I almost suggested it to a Canon-toting friend.  Yes, he could easily get the adaptall mount for his camera but without IBIS the lens would be pointless for handheld work.  In that case just go ahead and get out the big glass.

The Tamron 55BB is regarded as one of the best mirrors ever made and yet it would be mostly without point on a Canon or Nikon.

So... which is better... the one that works with any lens.

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