MrFotoFool said:Very niche lens - I wonder who it is for. Wouldn't astro photographers want a wider angle?
it would be wide field deep sky stuff, that lens would be great for the likes of orion or the antares region particularly on a crop body where you can get tighter framing on bigger objects while being able to shoot at 1.4
for example i used my 24-70II at 70mm on a modified 760D for this just last weekend
Antares, Rho Ophiuchi and Blue Horsehead by Tony, on Flickr
i quite regularly use my 135 1.8 for dso as well