I'm not saying don't buy it. But you must consider that you will still need an adapter and you will have to use full manual controls without any camera feedback. They are a great lens no risk. But are they really any better than a Sigma F/3.5 8mm Fisheye with the advantage of being camera matched and half the size/weight?
I think a lot of the "good thoughts" on this lens were written long before the release of a 5D or in fact the Sigma F/3.5 8mm. It may well be still classed as better! But how much better? ......and look at the price difference.
Have you looked at the results of this combination on the stats of the World Wide Panorama? Simon from this forum has this set up Canon 5D and Nikkor 8mm though the stats say this was with a Sigma 8mm - Hmm, I though Simon said he used the Nikkor with this one? Actually the WWP page does say so! Stat man made an error it appears?
You asked in another thread about (3) shots using a 5D and Sigma 8mm.
Here is one