I got this 8mm-180 degrees circular fish-eye for some virtual tours and really that is probably the only sensible use for this lens. It is hard to find other useful applications for this extreme circular fish-eye, so it is not very often in my bag. But when that happens it is fun to experiment to see what can be done with it.
I must say the sharpness and built quality is amazing. Chromatic aberration is very well controlled with very little need for correction.
Here the Willis Building and the Lloyds building in the City of London.
5D markII Sigma 8mm f/3.5 30 seconds at f/11