My Kowa has the strait eyepiece, but almost all the others I had before were angled. I just reached a point in life that I had trouble getting a good focus out of the angled ones. I think it's due to wearing bifocals. But it just could be me. The first Kowa I used was a 77mm angled one, and it worked better than the other angled ones I'd used, but still found myself moving my head around trying to get a sharp picture. Then I tried a few with strait eyepieces and never had a problem. I also liked using the strait one better from a prone shooting position.
gary