I'm new to the photography scene, and so far I'm more interested in the old prime lens so I picked up a few old 50mm. One of it is the OM 50mm f1.8, the lens itself is in pretty good condition aside from some cosmetic wears, and I got a triplus extension tube for the OM mount as well and that is also in pristine condition. I tried the combination out with the 50mm and the tube for some macro shots, but somehow the focus is all wacky, it looks more like tilt shift when I have the tube on. There would be only a just a 1/4 of the screen in an angle like a / is filled with focus-able view, the rest is just blurry. I'm currently clueless what could be the problem, as the lens itself can focus just fine without the tube, and the tube has no gaps or any damage that could potentially affect the image either (test with 1, 2 and 3 parts of the tube connected). Maybe veterans like you guys could give me an idea of what could cause it. Currently I'm at work so unable to upload sample images, will do later when I return to home.