Apologies if this should be in the Canon area. I put it here so as to get a general consensus.

My Camera - Canon 5D Mk III
My lens (for the purposes of this discussion) - 24-70 f2.8L

My question / Dilemma (bear with me) is this:

Ive long thought my 24-70 wasnt really wide enough for some landscapes and keep looking at the 16-35 MkII or 17-40, but not yet bought anything.

Ive also noticed that when shooting stars and the Milky Way that 24mm isnt normally wide enough either.

I know I could stitch for Landscapes but its a PITA / impossible when stacking startrails!

After reading a lot of threads, it strikes me many use about 10mm (on a cropped sensor) for night work and between 10mm & 22mm for landscapes (again cropped sensor), then last night I had a thought. What about using the 8-15mm Fisheye. I dont think this is as crazy as it may first seem. At 15mm on a full frame its VERY wide, only at 8mm is it circular and between 8 & 15 has varying degrees of circular-ness (is that even a word??)!

If 15mm on the full frame produces a decent image (albeit at f4), this could be used for landscapes and also for night work (may need to just lift the ISO up an extra notch to compensate for no f2.8). The missing bit obviously (compared to the 16-35) is the zoom from 15mm through to 24mm. The benefit though would be that I also have a fun lens for playing with (below 15mm).


Just had a thought... the 8-15mm wont accept filters because of its front curved element... Maybe the above is all rubbish because of this last nugget?

Any thoughts?

Thx
J