50 f/1.2 vs 50 f/1.4 - How much extra light?
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gdanmitchell
Registered: Jun 28, 2009
Total Posts: 9107
Country: United States

melcat wrote:
IMO most of these people would be better off with a normal zoom. Given that Canon sell four 50mm lenses, but only one, the f/1.2, is a modern one, they probably think so too. I wish it were an f/2, but they didn't do that.


That sounds like a quote from any of my many posts on the subject of lens choice. It also happens to be precisely in line with my primary points about lens selection and assessing individual need.

Hulot wrote:
I really believe [f/1.2] is only 1/3 of a stop [larger than f1.4] (as Canon has used a 1/3 stop number scale)


I wondered if anyone would catch that. It is why I wrote the ambiguous "about a half stop or so" - thinking that it might be wise to avoid a debate about that issue, too! ;-)

You are absolutely correct that the difference between f/1.4 and f/1.2 is less than half a stop.

Dan



Lars Johnsson
Registered: Jun 29, 2003
Total Posts: 33646
Country: Thailand

gdanmitchell wrote:
melcat wrote:
IMO most of these people would be better off with a normal zoom. Given that Canon sell four 50mm lenses, but only one, the f/1.2, is a modern one, they probably think so too. I wish it were an f/2, but they didn't do that.


That sounds like a quote from any of my many posts on the subject of lens choice. It also happens to be precisely in line with my primary points about lens selection and assessing individual need.

Hulot wrote:
I really believe [f/1.2] is only 1/3 of a stop [larger than f1.4] (as Canon has used a 1/3 stop number scale)


I wondered if anyone would catch that. It is why I wrote the ambiguous "about a half stop or so" - thinking that it might be wise to avoid a debate about that issue, too! ;-)

You are absolutely correct that the difference between f/1.4 and f/1.2 is less than half a stop.

Dan


I suppose all your advice doesn't apply to you. Looking at your gear least. From memory I would say your own gear list was a couple of FF bodies 10 L lenses including fast L lenses 4 different tripods and 8-9 bags to carry it in



jcolwell
Registered: Feb 10, 2005
Total Posts: 20498
Country: Canada

gdanmitchell wrote:
You are absolutely correct that the difference between f/1.4 and f/1.2 is less than half a stop.


Nope. He's wrong. f/1.2 is a half stop larger than f/1.4. To be more precise, f/1.189 is a half stop larger than f/1.414. I think it's quite fair to round 1.189 to 1.2 and 1.414 to 1.4 - don't you?

The math is based on powers of sqrt(2). Here's lists of full stops, half stops and third stops from f/1 to f/4, rounded to one decimal place.

full stops
f/
1
1.4
2
2.8
4

half stops
f/
1
1.2
1.4
1.7
2
2.4
2.8
3.4
4

third stops
f/
1
1.1
1.3
1.4
1.6
1.8
2
2.2
2.5
2.8
3.2
3.6
4


P.S. there is no YMMV - it's all in the math.



jerbear00
Registered: Jan 17, 2011
Total Posts: 666
Country: N/A

Awesome for a "normal" lens there is always so much back and forth on this topic about 50s in particular the L vs 50 1.4 vs sigma 1.4. Too many threads have beat this one to death.

I still read them as if waiting for divine revelation on the subject....

This doesn't answer your question but go read: http://www.lensrentals.com/blog/2012/01/the-great-50mm-shootout

My summation from owning the L, 50 1.8, 50 1.4, sigma 50 is that for the most part you are simply splitting hairs and each has it's place re: quality, price, focus, bokeh, rendering



jerbear00
Registered: Jan 17, 2011
Total Posts: 666
Country: N/A

Yup it's a 1/2 stop



gdanmitchell
Registered: Jun 28, 2009
Total Posts: 9107
Country: United States

jerbear00 wrote:
My summation from owning the L, 50 1.8, 50 1.4, sigma 50 is that for the most part you are simply splitting hairs and each has it's place re: quality, price, focus, bokeh, rendering


Yup, pretty much agree with that, and it is consistent with what I wrote.

Lars Johnsson wrote:
I suppose all your advice doesn't apply to you. Looking at your gear least. From memory I would say your own gear list was a couple of FF bodies 10 L lenses including fast L lenses 4 different tripods and 8-9 bags to carry it in


I never wrote about my specific equipment needs, nor did I write that people should own in specific gear or number of pieces of gear. However, if I felt it was remotely necessary (or relevant to the question about the 50mm lenses) I could explain how each piece is used and illustrate with photographs.

Lars, you are spinning off into ad hominem territory now.

jerbear00 wrote:
Yup it's a 1/2 stop


Sigh.

If half stops were calculated by averaging the two whole stop numbers, then we would find that the stop halfway between f/8 and f/4 was f/6. Last time I checked on my cameras, the silly manufacturers insisted that f/5.6 is actually found halfway between f/4 and f/8.

And, let's see, if f/1.2 is a half stop, then so is f/2.4 along with f/4.8. The whole stop midway between f/2.4 and f/4.8 would be calculated, according to the formula that would call f/1.2 a half stop, f/3.6. Gee, what happened to f/4?

You can learn a lot of amazing things about photography by reading photo forums! ;-)

Dan



jcolwell
Registered: Feb 10, 2005
Total Posts: 20498
Country: Canada

gdanmitchell wrote:
Lars Johnsson wrote:
I suppose all your advice doesn't apply to you. Looking at your gear least. From memory I would say your own gear list was a couple of FF bodies 10 L lenses including fast L lenses 4 different tripods and 8-9 bags to carry it in


I never wrote about my specific equipment needs, nor did I write that people should own in specific gear or number of pieces of gear. However, if I felt it was remotely necessary (or relevant to the question about the 50mm lenses) I could explain how each piece is used and illustrate with photographs.

You are spinning off into ad hominem territory now.

jerbear00 wrote:
Yup it's a 1/2 stop


Sigh.

If half stops were calculated by averaging the two whole stop numbers, then we would find that the stop halfway between f/8 and f/4 was f/6. Last time I checked on my cameras, the silly manufacturers insisted that f/5.6 is actually found halfway between f/4 and f/8.

And, let's see, if f/1.2 is a half stop, then so is f/2.4 along with f/4.8. The whole stop midway between f/2.4 and f/4.8 would be calculated, according to the formula that would call f/1.2 a half stop, f/3.6. Gee, what happened to f/4?

You can learn a lot of amazing things about photography by reading photo forums! ;-)

Dan


Half stops are not calculated by "averaging whole stop numbers". f/1.2 is the half stop between f/1.0 and f/1.4 because it equals sqrt(2)^(0.5), not because it is coincidentally the average of (1.0 + 1.4)/2 = 1.2. As I pointed out earlier, there is no YMMV.

The basic equation is the relationship between the diameter of a circle and its area. When you change the area by a factor of two (doubling or halving the amount of light it lets in), you change the diameter of the circle by a factor of the square-root of 2; i.e. sqrt(2). The f-stop is the ratio of focal length divided by apparent aperture diameter, as seen through the front element of the lens. One "step" in "full" f-stop numbers corresponds to one step in Exposure Value (EV), which means the amount of light is doubled or halved, and hence the f-stop changes by powers of sqrt(2), because that's the geometric ralationship between that amount of area change and the corresponding aperture diameter change.

Sometimes, you can learn new things on FM, especially if you actually pay attention to what is being discussed.



alundeb
Registered: Nov 06, 2005
Total Posts: 4243
Country: Norway

snapsy wrote:
I have both and the 50L is all about its rendering at f/1.2 - f/1.6, particularly the bokeh, which is highly unique. I actually prefer the 50 f/1.4 for general shooting because it's so incredibly sharp and less unwieldy.

Btw, most of the extra light of the 50L is wasted:
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues


The link above, combined with measured transmission of the two lenses : ...

http://www.dxomark.com/index.php/Lenses/Compare-Camera-Lenses/Compare-lenses/(lens1)/197/(brand)/Canon/(camera1)/436/(lens2)/196/(brand2)/Canon/(camera2)/436

(Click the "measurements" tab and then "transmission")

... should give the most accurate answer to how much extra light.

The measured T-stops are 1.4 and 1.6



gdanmitchell
Registered: Jun 28, 2009
Total Posts: 9107
Country: United States

So, then, the half-stop between f/2.4 and f/4/8 is f/3.6?

;-)

Dan

jcolwell wrote:
gdanmitchell wrote:
If half stops were calculated by averaging the two whole stop numbers, then we would find that the stop halfway between f/8 and f/4 was f/6. Last time I checked on my cameras, the silly manufacturers insisted that f/5.6 is actually found halfway between f/4 and f/8.

And, let's see, if f/1.2 is a half stop, then so is f/2.4 along with f/4.8. The whole stop midway between f/2.4 and f/4.8 would be calculated, according to the formula that would call f/1.2 a half stop, f/3.6. Gee, what happened to f/4?

You can learn a lot of amazing things about photography by reading photo forums! ;-)

Dan


Half stops are not calculated by "averaging whole stop numbers". f/1.2 is the half stop between f/1.0 and f/1.4 because it equals sqrt(2)^(0.5), not because it is coincidentally the average of (1.0 + 1.4)/2 = 1.2. As I pointed out earlier, there is no YMMV.

The basic equation is the relationship between the diameter of a circle and its area. When you change the area by a factor of two (doubling or halving the amount of light it lets in), you change the diameter of the circle by a factor of the square-root of 2; i.e. sqrt(2). The f-stop is the ratio of focal length divided by apparent aperture diameter, as seen through the front element of the lens. One "step" in "full" f-stop numbers corresponds to one step in Exposure Value (EV), which means the amount of light is doubled or halved, and hence the f-stop changes by powers of sqrt(2), because that's the geometric ralationship between that amount of area change and the corresponding aperture diameter change.

Sometimes, you can learn new things on FM, especially if you actually pay attention to what is being discussed.



jcolwell
Registered: Feb 10, 2005
Total Posts: 20498
Country: Canada

gdanmitchell wrote:
So, then, the half-stop between f/2.4 and f/4/8 is f/3.6?

;-)

Dan


Let's face it, neither of us has any idea what the other is talking about. At least, I know my math is right. BTW, it says the stop between f/4 and f/8 is f/5.7 (actually f/5.66). It's always been that way, but for some reason, the silly manufacturers insist on calling it f/5.6.



mttran
Registered: Nov 03, 2005
Total Posts: 6630
Country: United States

ok...ok...ok....it is not just about f-stops...none said anything about rendering of these two lenses, which one has more 3D effects than other



Hulot
Registered: Jan 22, 2012
Total Posts: 180
Country: N/A

so what reading do you get from your camera? what aperture can you dial in manually?

1.2 - 1.3 - 1.4 - 1.6 - 1.8 - 2
or
1.2 - 1.4 - 1.6 - 1.8 - 2

I am not owning a 50L so I cant tell


jcolwell wrote:
third stops




Peter Kotsa
Registered: Nov 02, 2007
Total Posts: 267
Country: Australia

The extra $1000 in this lens will be found in ......Micro-contrast, Colour, Bokeh, Build, and lastly f1.2
Also the resolution of the 50L at 1.2 is incredible.

The 50 1.4 only really becomes useable at around f2-2.2 (as sharpness and contrast finally catch up).
I have had three copies of the 50 1.4 in 15 years...all have been the same.....sharp from f2 up.

I purchased one copy of the 50L and have never looked back...great optic.



rabbitmountain
Registered: Aug 29, 2011
Total Posts: 940
Country: Netherlands

Dan,

If you go to Pizza Hut (for argument's sake let's assume you do) and you could choose between a 8", 12" or 16" size (for argument's sake let's assume that they offer those exact sizes), would you say that with a 16" pizza you can eat twice as much as with an 8" pizza and a 12" pizza is 1.5 times an 8"?

It's all about the Area, a mathematical excercise. Area = 0.25 x pi x Diameter x Diameter. Thus:
8" pizza: Area = 50.27 square inches
12" pizza: Area = 113.10 square inches
16" pizza: Area = 201,06 square inches

So, it turns out that the 16" pizza is 4 times the Area (and thus the weight) of an 8" pizza.

Now what if we would like to know the diameter size of a pizza that has exactly double the area of an 8" pizza? We would start the calculation with 100.54 sq. inches and our Diameter would be: 0.25 x pi x Diameter x Diameter = 100.54. Diameter = 11.31 inches.
For 25.135 sq.inches (half the Area of an 8" pizza), Diameter = 5.66 inches.
For 12.57 sq.inches (half the Area of a 5.66" pizza), Diameter = 4.00 inches

So if we're interested in calculating the half Area of each next pizza, starting from a 16" pizza we get:
16"
11.31"
8"
5.66"
4"
Should I go on?



retrofocus
Registered: Apr 19, 2007
Total Posts: 3734
Country: United States

alundeb wrote:
snapsy wrote:
I have both and the 50L is all about its rendering at f/1.2 - f/1.6, particularly the bokeh, which is highly unique. I actually prefer the 50 f/1.4 for general shooting because it's so incredibly sharp and less unwieldy.

Btw, most of the extra light of the 50L is wasted:
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues


The link above, combined with measured transmission of the two lenses : ...

http://www.dxomark.com/index.php/Lenses/Compare-Camera-Lenses/Compare-lenses/(lens1)/197/(brand)/Canon/(camera1)/436/(lens2)/196/(brand2)/Canon/(camera2)/436

(Click the "measurements" tab and then "transmission")

... should give the most accurate answer to how much extra light.

The measured T-stops are 1.4 and 1.6


Correct regarding the link - but this is not what I am seeing practically. The 50/1.2 lets a lot more light to the sensor. The 50/1.4 is much less light sensitive in this regard.



RobertLynn
Registered: Jan 05, 2008
Total Posts: 11513
Country: United States

My head hurts.



rabbitmountain
Registered: Aug 29, 2011
Total Posts: 940
Country: Netherlands

Now about the reasons I want the 50L:
When it comes to portraits and wedding photography, first thing that come to my mind are some gear independent things that attribute to an image that the client will like : get a good composition, the right angle, the right expression (timing). If you get all of that right, the gear becomes basically irrelevant, as long as it's not limiting you.

By limiting I mean in a dark church with no flash allowed (or the desire to keep from flash for IQ reasons) a 24-105 won't get me any shot, but either a 50/1.4 or 50/1.2 will get me the shot I want, and from the client's perpective they're probably equally good or bad.

So apart from the weather sealing, durability, AF speed, etc., purely in terms of IQ, is the 50/1.2 really that much better @f/1.2 than the 50/1.4 @f/1.4? I think a photographer will notice the difference, but will a client notice it too?

I think a lot of clients really will notice. For me, the 50L has this dreamy look when shot wide open. A dreamy look that goes perfectly with a wedding coverage, where a photographer stands before a task to capture events that chase those dreams. It fits perfectly. The 50L is able to give this dreamy bokeh look even at longer focusing distances like 12 feet. That is where a 50L can attribute to a great composition and timed shot and make it really special.

I'm even in the process of building my gear around the 50L. My current cameras are unable to AF the 50L with confidence, so I'm looking for another camera that will. It's that good. So far I've changed to an Ee-S focusing screen (for 5D) and sold my 40D. My next FF camera body will have to be one that focuses the 50L well.



rabbitmountain
Registered: Aug 29, 2011
Total Posts: 940
Country: Netherlands

RobertLynn wrote:
My head hurts.

Just go out and have a slice of pizza. That usually works for me Pizza solves many problems



mttran
Registered: Nov 03, 2005
Total Posts: 6630
Country: United States

Ralph, i love pizza....a big one, can't go wrong with that



RobertLynn
Registered: Jan 05, 2008
Total Posts: 11513
Country: United States

mttran wrote:
Ralph, i love pizza....a big one, can't go wrong with that

cutting weight..after competition I'll mow a pizza in honor of you guys.



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