Here are some pictures of the Angenieux 90/2.5 lens. It is part of my Alpa-Reflex collection and I have had it for years. Only lately did I find an Alpa -> m43 adapter on ebay that I ordered from Hong Kong. It is solidly built and infinity focus is correct. A slight inconvenient is that the top of the lens (distance scale, focusing wheel) is not completely centered, but this only a minor inconvienence that does not detract from its usefulness.
The lens has stood the long storage very well, focus, diaphragm, preset lever are still silky-smooth like new. Including the adapter, it weighs 550g and is 92mm long and can thus be used very well hand held.
The button on the top serves only on the Alpa to close the lens to the preset value and release the shutter. I very much like the aperture setting wheel, I find it much more user-friendly than the usual aperture rings. It has big engraved numbers that are easy to read and once you know the lens, you can set the aperture by click stops without even looking at it.
On the bottom of the lens you see the DOF preview button. It makes it easy to focus at full aperture and then close the diaphragm to the preset value in a snap.