50mm 1.4 or 85mm 1.8?

I've been eyeballing a Canon 50mm 1.4 and a Canon 85mm 1.8 and I decided I don't need both so I'm wondering which you guys would recommend.

Assuming that you're gonna keep the 50D body:
You already have a 50 thus I don't see the need of another (though "faster",but really not very usable up to f/2).
On the other hand,the 85/1.8 you're looking at could be a fine compliment to the lenses you have already.Aside that it's IQ and build is really great for what it costs,it should be the longest in your lineup (think at it in terms of FOV:85 x 1.6 = 136,so you're in the 135mm-lenght ballpark,in case you aim towards closeup portraits...but not only).
HTH!
Cheers,

I have both and love both. The 85 is far and away a much cleaner lens, especially wide open - far less corner softness, less vignetting, better color and contrast. I find the 50 1.4 too soft to shoot wide open and I often have to stop it down to 2.0 before I'm happy with it but it is still a great lens - that extra half stop over the 1.8 can come in handy when you absolutely have to use it.

All that being said, is there anything particular you're looking to shoot with this new lens?

85 1.8 is a great lens but could be somewhat limited in its use on your 50D.

You've already got a 50, get the 85. I've got both the 50 1.4 and the 85 1.8, the combinations make good compliments to each other, even on a crop. My 85 tends to see a little more use than the 50, my 135 sees more use than both of those.

rvank wrote in post #15649766
I have both and love both. The 85 is far and away a much cleaner lens, especially wide open - far less corner softness, less vignetting, better color and contrast. I find the 50 1.4 too soft to shoot wide open and I often have to stop it down to 2.0 before I'm happy with it but it is still a great lens - that extra half stop over the 1.8 can come in handy when you absolutely have to use it.

I tend to agree with that assessment, but considering the 85mm f1.8 is also a little better stopped down to f2-2.2, we are at a level playing field. Both are excellent at f2+, but the 50mm still has a stop in reserve. It's also not bad at those larger apertures if you are careful to centrally place your subject.

In terms of low light, consider 50mm gives about a stop of advantage based on focal length, and then adds in nearly another stop due to max aperture. In the dark, you might be at 50mm, 1/100, f1.4 and ISO 3200, where you'd be at 85mm, 1/160, f1.8 and ISO 12800 on the 85mm. (I think that math is right, it's about 1.66 stops difference)