Using a 5D2 (i?? - -never heard of) in my eyes itÂ´s wise to use the 15mm. If you KNOW you will use it with only 4 shots for being very quick take the 8 - 15mm. You need - as said - only 4 shots to cover a sphere, but you loose resolution.
So i wouldnÂ´t do that.
Using the 15mm you anyway need only 6 shots when you make 5@-12° + Z. I donÂ´t know whether the NN provides a click-stop for that. So the difference in speed is not remarkable. The difference in resolution is!
I use 5@-12° + Z all the time. hereÂ´s an example: www.360impressions.de/LiR_FE_Oben
(a test-shot in a very narrow space)
1. Why do your prefer the Canon 15mm FE over the newer Canon 8-15mm zoom FE which would seem to be a more flexible option.
2. I had read that the Canon 15mm fisheye is very hard to fidn these days as it was discontinued by Canon some time ago. Or am I mistaken?
1) i donÂ´t need 8mm on fullframe. It saves TWO shots - but it costs resolution by only covering a fraction of the format due to being circular.
2) Right, Canon stopped the production of the 2,8/15mm FE - but you can get it still, and at a remarkable lower price than the 4/8-15mm, which is around 1200.-â‚¬.
Btw.: i find 1:2,8 preferable compared to 1:4. Using a fisheye you can shoot max. wide open and have reasonable DOF nevertheless.
ItÂ´s a very sharp lens - i do lots of work with it.
PS: the 8-15mm is clever when you work with FX and DX cameras. Here you have FOUR FE functions. FF on FF, FF on DX, circular on FX and almost-circular on DX.