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Thread started 28 Sep 2006 (Thursday) 09:49

# f1.4 versus f1.2

Sep 28, 2006 09:49 |  #1

Compared to f1.4, how much more light will f1.2 let in? Is it less than half a stop (.44)? I'm not sure if I am calculating this right...

Todd

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Sep 28, 2006 09:52 |  #2

It is one-half stop.

full stop increments 1, 1.4, 2, 2.8, 4, 5.6, etc.

Mike, The Keeper of the Archive

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Sep 28, 2006 10:15 as a reply to  @ In2Photos's post |  #3

Well, considering how all of the f-stops are rounded anyways, you can take f/1.2 to be both a half stop and a third stop faster than f/1.4.

-- Michael (a.k.a. SimonG)
EOS 5D | 17-40 f/4L | 24-105 f/4L | 40 f/2.8 | 50 f/1.4 | 85 f/1.4 | 430EX | Zenfolio

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Sep 28, 2006 10:18 |  #4

SimonG wrote in post #2048741
Well, considering how all of the f-stops are rounded anyways, you can take f/1.2 to be both a half stop and a third stop faster than f/1.4.

So I guess my .44 is accurate.

Todd

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Sep 28, 2006 10:39 |  #5

Square each. 1.2^2 = 1.44; 1.4^2 = 1.96. Subtract 1.96-1.44 = .52. Divide .52/1.44 = .36 or about 1/3 stop.

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Sep 28, 2006 10:42 |  #6

The only difference between the 1.4 and 1.2 is prestige. 1/3 stop is not enough to make a difference, since you can adjust ISO.

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Sep 28, 2006 10:45 |  #7

davidfig wrote in post #2048839
The only difference between the 1.4 and 1.2 is prestige. 1/3 stop is not enough to make a difference, since you can adjust ISO.

Unless, of course, you're already at the limit and absolutely desperate for light....

...or Dante.

Did you lose Digital Photo Professional (DPP)? Get it here. Cursing at your worse-than-a-map reflector? Check out this vid!

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Sep 28, 2006 10:55 |  #8

Aperture range: 1.0; 1.1; 1.2; 1.4; 1.6; 1.8; 2.0; 2.2; 2.5; 2.8 etcetera.

This is not just about prestige..... Sometimes it is not possible to use a higher ISO since you allready maxxed out. (allthough it is doubtfull that the extra 1/3 stop will help) Also an f/1.2 lens is stopped down when used at f/1.4 so (hopefully) delivers better IQ then the f/1.4 lens fully opened.

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Sep 28, 2006 12:04 |  #9

runninmann wrote in post #2048826
Square each. 1.2^2 = 1.44; 1.4^2 = 1.96. Subtract 1.96-1.44 = .52. Divide .52/1.44 = .36 or about 1/3 stop.

Sure, but like I said, there's a lot of rounding going on here that prevents your calculation from being 100% accurate (i.e. your idealized aperture value of 1.4 should really be √2, or 1.4142). As I said, it's impossible to know precisely how much faster a lens is in this range unless you know the actual diameter of the lens wide open... but it's somewhere in the range of 1/3 to 1/2 stop faster.

-- Michael (a.k.a. SimonG)
EOS 5D | 17-40 f/4L | 24-105 f/4L | 40 f/2.8 | 50 f/1.4 | 85 f/1.4 | 430EX | Zenfolio

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Sep 28, 2006 12:05 |  #10

I take a lot of shots @f/1.2.

Recent examples:

HOSTED PHOTO

HOSTED PHOTO

As you can see, in very low light situations like this, that 1/3d stop helps. Besides that, the 85L is a very sharp lens, according to the photodo test one of the sharpest.

P.

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Sep 28, 2006 12:47 |  #11

cdi-ink.com wrote in post #2048854
Unless, of course, you're already at the limit and absolutely desperate for light....

...or Dante.

Ok, thats it bub! me and you, bike racks after school!!

Dante
I am not an Lcoholic. Lcoholics go to meetings!
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Sep 28, 2006 13:49 |  #12

Dante King wrote in post #2049292
Ok, thats it bub! me and you, bike racks after school!!

*Hides in his locker*

Did you lose Digital Photo Professional (DPP)? Get it here. Cursing at your worse-than-a-map reflector? Check out this vid!

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Sep 28, 2006 15:30 |  #13

SimonG wrote in post #2049148
Sure, but like I said, there's a lot of rounding going on here that prevents your calculation from being 100% accurate (i.e. your idealized aperture value of 1.4 should really be √2, or 1.4142). As I said, it's impossible to know precisely how much faster a lens is in this range unless you know the actual diameter of the lens wide open... but it's somewhere in the range of 1/3 to 1/2 stop faster.

I don't disagree at all that liberal use of rounding is used in discussions of aperture values. That's why my answer was "about 1/3 stop". The purpose of showing the calculations was to assist others who might have a similar question about any 2 relative aperture values. You know..."Give a man a fish...."

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Sep 28, 2006 15:37 as a reply to  @ runninmann's post |  #14

I wasn't picking on your method by any means. I was just pointing out that the result of any calculation can only be as good as the input values, and in this case, those are not particularly well defined due to the heavy amount of rounding that exists in these standard aperture values.

-- Michael (a.k.a. SimonG)
EOS 5D | 17-40 f/4L | 24-105 f/4L | 40 f/2.8 | 50 f/1.4 | 85 f/1.4 | 430EX | Zenfolio

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Sep 28, 2006 15:48 |  #15

cdi-ink.com wrote in post #2048854
Unless, of course, you're already at the limit and absolutely desperate for light....

...or Dante.

You're a funny guy

"This aggression will not stand, man."

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f1.4 versus f1.2
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