Canon 50mm 1.4 DOF Vs 85mm 1.8 Help

Canon EF 85mm f/1.2L II USM

02/15/2011 12:45:16 PM · #1

I need some help determining whether to get the 85mm 1.8

I shoot aps-c only and have a canon 50mm 1.4, which I shoot wide open. If I were to buy the 85mm 1.8, would I get more shallow DOF compared to the 50mm?? If so! would it be a big improvement? and also, is the quality of the bokeh on the 85mm 1.8 better than the 50mm 1.4?

No full frame only APS-C

Cory

Canon EOS-1D Mark IV

02/15/2011 01:22:53 PM · #2

No time right now to answer all of the finer points, but I can tell you this: I had the choice, purchased the 85 1.8, and couldn't be happier.

tholmir

Canon EOS-400D Rebel XTi

Canon EF-S 18-55mm f/3.5-5.6

02/15/2011 01:29:11 PM · #3

You can use this tool to compare the DOF: //www.dofmaster.com/dofjs.html

Bear_Music

Samsung Galaxy S24, S24+, S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

02/15/2011 02:24:19 PM · #4

At a given distance and wide open, significantly less DOF with the 85mm. Shooting for the same angle of coverage (i.e. stepping far enough back to frame the scene the same as with the 50mm) you'll actually have slightly more DOF with the 85mm than with the 50mm...

R.

Samsung Galaxy S24, S24+, S24 Ultra

02/15/2011 02:27:42 PM · #5

Originally posted by tholmir:

You can use this tool to compare the DOF: //www.dofmaster.com/dofjs.html

At maximum apertures for both lens. 50meters (@1.4) vs 85meters (@1.8) distance to compensate for the 85mm. The 50mm has a slightly shallower DOF of 5meters. Did I do it right???

Bear_Music

Sony 24-70mm F4 Vario-Tessar T* FE OSS

02/15/2011 02:34:02 PM · #6

I'm not sure your premise is correct (that 85mm lens at 85 metres has same angular coverage as 50mm lens at 50 metres) but the result's close enough, yes. It's interesting, I've never thought of what is the ratio between angular coverage and focal length in quite those terms. It'd be fascinating if you're correct. Did you dig that info up somewhere or is it just a fly-by-night stab-in-the-dark?

And yes, you used the DOF calculator correctly, for those given distances.

R.

Samsung Galaxy S24, S24+, S24 Ultra

02/15/2011 02:38:53 PM · #7

Originally posted by Bear_Music:

I divided 85 by 50 and used 1.7 Still uncertain of the calculation lol

Bear_Music

Sony 24-70mm F4 Vario-Tessar T* FE OSS

02/15/2011 03:24:15 PM · #8

Well, the actual angles of view, diagonally, for the two lenses are 28.6 and 46.8 (for the 85mm and the 50mm, respectively). But I have yet to find anyplace that translates that into how much DISTANCE you have to back up to frame the same subject.

That is to say, if at 10 feet your 50mm frames up a subject of "x" height, how far do you have to back up to frame the same subject with the 85mm? Does it follow that simple multiplier?

R.

Message edited by author 2011-02-15 15:25:27.

02/15/2011 03:41:44 PM · #9

Originally posted by Bear_Music:

It approximately follows that rule, for longer focal lengths. It's exactly true for equiangular fisheyes, for what that's worth - next to nothing, LOL!
The reason it's a close approximation for long focal lengths is that such lenses are close to equiangular, whereas WA lenses are definitely *not*! You can see there is some divergence, since 85/50 is 1.7, whereas 46.8/28.6 is 1.63, somewhat smaller than expected for the ratio of focal lengths. I'd expect this, because for smaller focal lengths, you gain less AoV than you think; going from 50mm to 25mm, you don't get twice the AoV.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

02/15/2011 07:52:47 PM · #10

So the 85mm 1.8 is'nt going to give me anymore shallow DOF than my 50mm 1.4
And neither will the 100mm 2.0

chromeydome

Nikon D7000

02/15/2011 08:04:00 PM · #11

It isn't just the actual dof metric that matters, but the "character" of it. That is not just attributable to the numbers, the focal length, field of view, etc, but a characteristic of the specific lens design. I am not directly familiar with the canon versions, but for me the Nikon 85 1.4 is unlike any of my primes or zooms in that it has a certain look/feel/quality. Bokeh depends on the lens design, not just the focal length (number of blades forming the diaphragm, etc.)

So the 85 might not be different in the dof mathematics, but it well might produce different looking images. Both are great primes to have. Maybe you can rent an 85 (locally or online), or perhaps borrow one to try it out, see what differences there may be, and if they matter enough to you to purchase.

Canon EF 85mm f/1.2L II USM

02/15/2011 08:20:41 PM · #12

Originally posted by dmadden:

So the 85mm 1.8 is'nt going to give me anymore shallow DOF than my 50mm 1.4
And neither will the 100mm 2.0

For the same subject framing, no. They are all pretty close in fact. For the same distance, there is an advantage to the 85/1.8 over the 50/1.4, and a small advantage to the 100/2 over the 85/1.8 in achieving narrow DoF. But then again, the framing is radically different.

Cory

Canon EOS-1D Mark IV

02/15/2011 09:11:39 PM · #13

Sounds to me like you need to pony up and just buy a used 5D, that'll solve your problems very nicely.

02/15/2011 10:13:50 PM · #14

Originally posted by coryboehne:

Sounds to me like you need to pony up and just buy a used 5D, that'll solve your problems very nicely.

Most definitely!!! A 5d is definitely the way forward. Maybe end of year I'll be able to afford a used 5d original, watching keh.com. I'll continue with the 50mm 1.4 for now.

Sony 16-50mm f/3.5-5.6 E-mount

03/17/2011 11:57:56 PM · #15

I got the 85mm. It delivers. I'm extremely happy :)

jmsetzler

Sony Alpha a6000

03/18/2011 12:19:49 AM · #16

I have both lenses and prefer the 85 simply for the longer focal length. The DOF difference is rather insignificant when using both wide open.

robs

Canon EOS R6 Mk II

Canon EF 24-105mm f/4.0L IS

03/18/2011 12:22:22 AM · #17

I have both.... You could always just not choose like me :-) I prefer the DOF & feel on the 50mm but the 85 is good once you get rid of the CA.

jmsetzler

Sony Alpha a6000

Sony 16-50mm f/3.5-5.6 E-mount

03/18/2011 12:36:54 AM · #18

Originally posted by robs:

I have both.... You could always just not choose like me :-) I prefer the DOF & feel on the 50mm but the 85 is good once you get rid of the CA.

I can't tell any difference in CA between the two.

Sony 16-50mm f/3.5-5.6 E-mount

03/18/2011 01:20:50 PM · #19

Originally posted by dmadden:

I got the 85mm. It delivers. I'm extremely happy :)

I think for what you do it will be a workhorse :-)
Now, if you like the 85, give the 135/2 a try sometime. But don't do it unless you are prepared to lust after it.

jmsetzler

Sony Alpha a6000

03/18/2011 02:39:50 PM · #20

Originally posted by kirbic:

Originally posted by dmadden:
I got the 85mm. It delivers. I'm extremely happy :)

I think for what you do it will be a workhorse :-)
Now, if you like the 85, give the 135/2 a try sometime. But don't do it unless you are prepared to lust after it.

The 135 f/2 is one of the next lenses on my list. I recently came into a good bit of money that I promised myself I'd spend on my photography hobby and the 135 was on the possibility list but it didn't make the cut. That is a sweet lens. The Lensbaby composer will probably be one step ahead of the 135 though :)