50mm or 85mm on a 40d

ok im contradicting myself on these to buy. mostly want the lowest f stop like a 1.2 or 1.4 but reason is i want it for more indoor potraits wedding and pics. not sure which is the better choice out of them to get

85mm on a 40d isn't wide enough for portraits, in my opinion. I would go with the 50mm.

Just try both focal lengths on your 17-85 and you'll see.

I have the 1.4 and like it (light too). It does a nice job with portraits....but then again I'm not a wedding photographer making a living with my gear.

I'd go with the 50 for portraits on a 40d.

The 85mm is more like a 135 on a FF camera. 135 is usually too tight for most portraits. IT's more of a fashion look.

Plus, the 50mm Canon 1.4 has a more useable dynamic range than the 85 1.8. The 85 is very contrasty and can be more unforgiving on people.

Unity Gain wrote in post #4221603
Plus, the 50mm Canon 1.4 has a more useable dynamic range than the 85 1.8. The 85 is very contrasty and can be more unforgiving on people.

Lenses have dynamic range?

DocFrankenstein wrote in post #4222401
Lenses have dynamic range?

oh puleeze....you know exactly what I mean

The 50 will keep more detail in the highlights and detail in the shadows in comparison to the 85

BTW - i know this from experience and not from reading little nerd charts on the internets

On a crop I would go 50mm and on FF 85mm ... in fact, I have .

Unity Gain wrote in post #4223630
oh puleeze....you know exactly what I mean

The 50 will keep more detail in the highlights and detail in the shadows in comparison to the 85

BTW - i know this from experience and not from reading little nerd charts on the internets

I'll be damned if I anybody can tell the image quality difference between the two primes at f/4. I certainly can't.

DocFrankenstein wrote in post #4223664
I'll be damned if I anybody can tell the image quality difference between the two primes at f/4. I certainly can't.

Me either. And lenses have no impact on the dynamic range capture by the sensor. I think Unity doesn't understand the term.

Beside, f/4 (or any other set of equal apertures) on either lens allows the same amount of light into the camera, all other things being equal. Details in the shadows and hightlights will be no different with the 50mm vs. 85mm given the same lighting conditions and exposure.

Mark

I would go Sigma 30 1.4 on the 40D...it is more like a 50 on FF

Harleypugs wrote in post #4225855
I would go Sigma 30 1.4 on the 40D...it is more like a 50 on FF

What he said or the Canon 28 f/1.8... take your 17-85, set it to 30 50 and 85, walk around your house and see what works...