A reminder for some memebers as to what the F stop is all about.

Started Jan 26, 2014 | Discussions
gsergei Contributing Member • Posts: 841
A reminder for some memebers as to what the F stop is all about.
17

Hi, all.

I've just had a quick look at the thread started by Dave Gaines about equivalence , again. He has made a very good point overall. Surprisingly, there are still photographers who fundamentally don't know what the aperture is all about. They say things like " convince me, that the amount of light going through Olympus 25/2.8 is the same compared to Canon, e.g., 50/1.4 set to 2.8". I have to disappoint you: YES ,it is the same. Why? -because it is a relative measure, not absolute. F2.8 on a Lumix LX3 allows the same illumination of sensor as PL 25/1.4 set to F2.8, the same as Canon 50/1.4 set to F2.8 !!!

also there is a lot of "expert talk" that bigger lenses allow more light and therefore this results in less noise in the image. This is total BS.

Now let's go through some lesson of optics. Some people visiting this website have no knowledge about the school items like : candela (don't confuse with Nelson Mandela), lumen, brightness, decibel, voltage, Amper, semiconductor electronic noise level, relative to signal vs absolute, etc.

So, F2 on a lens means that this diameter of the opening of the optical instrument can fit TWO times into its focal length. For a 50 mm F2 lens it means that the aperture  diameter at F2 is 25 mm. That's it, people. It has  never meant FF versus 4/3 versus whatever sensor/film size you had in your camera. Just the optical geometry. Easy ? Accordingly , F11 means that this diaphragm /aperture diameter will fit 11 times into the instrument's focal length. It's been like that since the inception of photography in the 19th century.

Now about the sensor noise on FF cameras vs. 4/3 vs anything else. The ONLY reason why they (FF) have less noise and better dynamic range is because their individual photosites are BIGGER electronic devices. Any semiconductor/ transistor/ diode has its electronic noise, because inside its P-N-P or N-P-N layers there are electrons which move randomly even when there is no "useful" signal. This chaotic movement is called "noise". A bigger semiconductor device can put through higher DC current and have "relatively" less noise.

The DPR once had a very useful parameter in the camera specification table describing the sensor's photosite in micrometers. there one could easily see that larger Canikons had bigger photosites, something like 8 micrometers vs Olympus's (don't remember precisely) 4.6 or something like that,  therefore their light sensitive "transistors" were bigger and could provide higher DC current compared to Olympus's or any other smaller sensor. It is This DC micro current that gives you higher DR and less noise, NOT the size of the sensor. Mind you , if Canon were to put 50 megapixel into its FF sensor it will have a much worse performance for noise and DR compared to their own 16 Mp or whatever on their current offerings. Again it has to do with pixel density (diodes per square mm) and size of the electronic device,it has nothing to do with 36x24 mm. If Olympus were to put only 3 Mp into their 4/3 sensor it would be the same of better than any Canikon you know in terms of noise and DR, but then you would complain about the low resolution, yeah, right !

The megapixel race is for stupid consumers and marketing boys/ploys, it has nothing to do with photography. I am totally against it. I don[t need even 16 MP on my EM1 and would love to see a new Olympus sensor with 10 or even 8 MP but with a higher quality sensor properties. That's it.

In the mean time : kudos to Olympus engineers for designing their fine lenses !

thank you for reading and now I will retire to my morning coffee.

Photo amen to all of you.

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OP gsergei Contributing Member • Posts: 841
Ah, sorry for "memebers".

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Silverback46
Silverback46 Senior Member • Posts: 1,368
Re: Ah, sorry for "memebers".

Isn't that how you spell members in the West?....hmmm maybe that's the East coast spelling!

Silver

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Jim Salvas
Jim Salvas Veteran Member • Posts: 5,670
Re: Ah, sorry for "memebers".

No, "memebers" are people who post memes on Facebook.

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Silverback46
Silverback46 Senior Member • Posts: 1,368
Re: +1 nt

No text.

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Ben Herrmann
Ben Herrmann Forum Pro • Posts: 20,697
Gosh - that complicates everything...

I always thought of myself to be a "remember..." 

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Have a great one....
Bernd (Ben) W. Herrmann
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Ben Herrmann
Ben Herrmann Forum Pro • Posts: 20,697
Oh boy - this should get really good. I can't wait to....

see what Sergey Green has to say about all of this.  He always seems to pop in when discussions about full frame vs other sensor dialogues are concerned.  This should get interesting.

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Have a great one....
Bernd (Ben) W. Herrmann
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OP gsergei Contributing Member • Posts: 841
A suggestion.
4

People on this forum who don't understand the F stop concept and continue to argue about the superiority of the so called FF cameras from now on are to be called "memebers" !

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CollBaxter
CollBaxter Forum Pro • Posts: 12,724
F......STOP and popcorn.
4

F......STOP   is what is what my wife shouted  when I nearly ran over a old lady with a walker at the traffic lights today.

I am going to put some popcorn in the microwave.

Let see.

Hmmmmm GB , SG R3D will be along shortly.

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OP gsergei Contributing Member • Posts: 841
Thanks for the humor, Colin,

I had a good laugh.

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TrapperJohn Forum Pro • Posts: 16,488
Is photosite size that relevant any more?
1

Back in the E1/E500 days, there was a marked difference between their output, and that of, say, the Canon 5D, under most circumstances.

Today, if you put the EM5 or EM1 up against the best FF, the noise advantage doesn't really become visible until ISO6400, and even then, it's not a huge difference. Not like it was in the mid 2000's.

What has happened in the intervening years is - sensor tech has improved a lot. What that has resulted in is bringing the 4/3 sensor more on a par with the larger ones, when used under typical photo circumstances. Both sensors got better, but you have to be really pushing things to see a substantial difference, in the year 2014.

So while it's easy to say 'bigger is better', that does not quantify how much better, or under what circumstances it will be better. That is contingent upon the state of the art of sensor tech, and the situation that the sensor is being used.

There really aren't any absolutes. MF should be better than FF, but for a variety of reasons, some technical, some practical, it isn't as good.

By today's standards, the 'difference' in terms of noise between 4/3 and FF, isn't nearly the factor it once was.

Sergey_Green
Sergey_Green Forum Pro • Posts: 11,993
Re: A reminder for some memebers as to what the F stop is all about.
1

There is no f2, there is f/2. And so whatever you want to remind members of, I think it would be better if you learned what it means first yourself. And how it relates to the larger imager behind it. Slowly.

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- sergey

veroman Veteran Member • Posts: 4,862
Re: A reminder for some memebers as to what the F stop is all about.
10

Sergey_Green wrote:

There is no f2, there is f/2 ...

Wow. Big difference. Surprised nobody caught this before. What a terrible "error."   

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RoelHendrickx
RoelHendrickx Forum Pro • Posts: 26,617
OK... this sounds distinctly
15

Sergey_Green wrote:

There is no f2, there is f/2. And so whatever you want to remind members of, I think it would be better if you learned what it means first yourself. And how it relates to the larger imager behind it. Slowly.

This sounds distinctly like really wanting to say something without having anything to say.

We get that all the time with our teenage son.

We will remark on something about his behaviour or whatever; and he knows that we are right; but instead of just admitting it, he tries to find a mispronunciation in what we said.

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DRB in NM
DRB in NM Regular Member • Posts: 188
Re: Is photosite size that relevant any more?
1

TrapperJohn wrote:

Back in the E1/E500 days, there was a marked difference between their output, and that of, say, the Canon 5D, under most circumstances.

Today, if you put the EM5 or EM1 up against the best FF, the noise advantage doesn't really become visible until ISO6400, and even then, it's not a huge difference. Not like it was in the mid 2000's.

What has happened in the intervening years is - sensor tech has improved a lot. What that has resulted in is bringing the 4/3 sensor more on a par with the larger ones, when used under typical photo circumstances. Both sensors got better, but you have to be really pushing things to see a substantial difference, in the year 2014.

So while it's easy to say 'bigger is better', that does not quantify how much better, or under what circumstances it will be better. That is contingent upon the state of the art of sensor tech, and the situation that the sensor is being used.

There really aren't any absolutes. MF should be better than FF, but for a variety of reasons, some technical, some practical, it isn't as good.

By today's standards, the 'difference' in terms of noise between 4/3 and FF, isn't nearly the factor it once was.

+1. It does seem that the larger pixels don't exhibit the noise advantage that they used to have. I imagine that pixel efficiency is getting so good that something else is contributing more to the noise (e.g., connecting metal line length/size in the sensor IC??? FF sensor=longer lines=more resistance=more noise???). I dunno. Maybe I'll ponder it some more.... Nah. I think I'll just go out and take some pictures:-)

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bobn2
bobn2 Forum Pro • Posts: 62,183
Re: A reminder for some memebers as to what the F stop is all about.
7

veroman wrote:

Sergey_Green wrote:

There is no f2, there is f/2 ...

Wow. Big difference. Surprised nobody caught this before. What a terrible "error."

It's a silly little thing, but quite important. The 'f2' notation doesn't tell you what's going one. For instance, if you say

'The aperture of the lens if f2' it sounds like the aperture is 2 and it's measured in 'effs'. That is quite wrong, the aperture isn't two.

If you say 'the aperture of the lens is f/2' what you are saying is 'the aperture of the lens is f divided by two', so then you ask, what is 'f' - of course it's the focal length, so 'the aperture' is 'the focal length divided by two' and is measured in units of distance, usually millimetres.

So, if someone tells you that the aperture of a 50mm f/2 lens and a 25mm f/2 lens is the same, they are wrong. in the case of the 50mm lens it is 50/2 mm, = 25mm and in the case of the 25mm lens it is 25/2 mm = 12.5mm. If both lenses are collecting light from the same angle of view (for instance because the 50mm lens is working with a sensor of twice the linear dimensions of the 25mm lens, then it is collecting from the same solid angle over four times the area, so it collects four times the amount of light.

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Bob

xtforest
xtforest Contributing Member • Posts: 605
Re: OK... this sounds distinctly

+1

cheers,

Rob

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bobn2
bobn2 Forum Pro • Posts: 62,183
Re: Is photosite size that relevant any more?
2

DRB in NM wrote:

TrapperJohn wrote:

Back in the E1/E500 days, there was a marked difference between their output, and that of, say, the Canon 5D, under most circumstances.

Today, if you put the EM5 or EM1 up against the best FF, the noise advantage doesn't really become visible until ISO6400, and even then, it's not a huge difference. Not like it was in the mid 2000's.

What has happened in the intervening years is - sensor tech has improved a lot. What that has resulted in is bringing the 4/3 sensor more on a par with the larger ones, when used under typical photo circumstances. Both sensors got better, but you have to be really pushing things to see a substantial difference, in the year 2014.

So while it's easy to say 'bigger is better', that does not quantify how much better, or under what circumstances it will be better. That is contingent upon the state of the art of sensor tech, and the situation that the sensor is being used.

There really aren't any absolutes. MF should be better than FF, but for a variety of reasons, some technical, some practical, it isn't as good.

By today's standards, the 'difference' in terms of noise between 4/3 and FF, isn't nearly the factor it once was.

+1. It does seem that the larger pixels don't exhibit the noise advantage that they used to have. I imagine that pixel efficiency is getting so good that something else is contributing more to the noise (e.g., connecting metal line length/size in the sensor IC??? FF sensor=longer lines=more resistance=more noise???). I dunno. Maybe I'll ponder it some more.... Nah. I think I'll just go out and take some pictures:-)

The truth is that the pixel size argument was always nonsense. Nothing has changed.

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Bob

bobn2
bobn2 Forum Pro • Posts: 62,183
Re: A reminder for some memebers as to what the F stop is all about.
11

gsergei wrote:

Hi, all.

I've just had a quick look at the thread started by Dave Gaines about equivalence , again. He has made a very good point overall. Surprisingly, there are still photographers who fundamentally don't know what the aperture is all about.

If you're going to make statements like that, best to ensure that you know 'what aperture is all about' in the first place.

They say things like " convince me, that the amount of light going through Olympus 25/2.8 is the same compared to Canon, e.g., 50/1.4 set to 2.8". I have to disappoint you: YES ,it is the same. Why? -because it is a relative measure, not absolute. F2.8 on a Lumix LX3 allows the same illumination of sensor as PL 25/1.4 set to F2.8, the same as Canon 50/1.4 set to F2.8 !!!

This is wrong. The f-number dictates the amount of light per unit area, so all lenses set to f/2.8 will project the same amount of light per unit area onto a sensor behind them. That means put a FF sensor behind a f/2.8 lens it will collect four times the amount of light than wiill a Four thirds sensor behind an f/2.8 lens.

also there is a lot of "expert talk" that bigger lenses allow more light and therefore this results in less noise in the image. This is total BS.

If 'total BS' means 'the truth', yes, it is.

Now let's go through some lesson of optics. Some people visiting this website have no knowledge about the school items like : candela (don't confuse with Nelson Mandela), lumen, brightness, decibel, voltage, Amper, semiconductor electronic noise level, relative to signal vs absolute, etc.

So, F2 on a lens means that this diameter of the opening of the optical instrument can fit TWO times into its focal length. For a 50 mm F2 lens it means that the aperture diameter at F2 is 25 mm. That's it, people. It has never meant FF versus 4/3 versus whatever sensor/film size you had in your camera. Just the optical geometry. Easy ? Accordingly , F11 means that this diaphragm /aperture diameter will fit 11 times into the instrument's focal length. It's been like that since the inception of photography in the 19th century.

Frankly, your sarcasm is misplaced. Everyone discussing this knows that. The question is, what is the implication of that fact.

Now about the sensor noise on FF cameras vs. 4/3 vs anything else. The ONLY reason why they (FF) have less noise and better dynamic range is because their individual photosites are BIGGER electronic devices. Any semiconductor/ transistor/ diode has its electronic noise, because inside its P-N-P or N-P-N layers there are electrons which move randomly even when there is no "useful" signal. This chaotic movement is called "noise". A bigger semiconductor device can put through higher DC current and have "relatively" less noise.

Actually, you don't know how a sensor works at all. It's not a current collecting device, it's a charge collecting device. The precise relationship between the size of various components in a pixel is complex, but on the whole, small pixels do not demonstrate any higher electronic noise than big ones. In any case, the electronic noise is only a very small component of the overall noise in an image, and only really apparent in the hsadows. Most image noise is 'photon shot noise' which is the noise due to the quantum nature of light (i.e. it is not a continuous phenomenon). The more photons you collect, the better the signal to noise ratio. that's why bigger sensors (behind the same f-number lens) display better signal to noise ratio.

The DPR once had a very useful parameter in the camera specification table describing the sensor's photosite in micrometers. there one could easily see that larger Canikons had bigger photosites, something like 8 micrometers vs Olympus's (don't remember precisely) 4.6 or something like that, therefore their light sensitive "transistors" were bigger and could provide higher DC current compared to Olympus's or any other smaller sensor. It is This DC micro current that gives you higher DR and less noise, NOT the size of the sensor. Mind you , if Canon were to put 50 megapixel into its FF sensor it will have a much worse performance for noise and DR compared to their own 16 Mp or whatever on their current offerings. Again it has to do with pixel density (diodes per square mm) and size of the electronic device,it has nothing to do with 36x24 mm. If Olympus were to put only 3 Mp into their 4/3 sensor it would be the same of better than any Canikon you know in terms of noise and DR, but then you would complain about the low resolution, yeah, right !

Sorry, the stuff about 'DC micro current' is completely wrong. Sensors measure charge not current.

The megapixel race is for stupid consumers and marketing boys/ploys, it has nothing to do with photography. I am totally against it. I don[t need even 16 MP on my EM1 and would love to see a new Olympus sensor with 10 or even 8 MP but with a higher quality sensor properties. That's it.

In the mean time : kudos to Olympus engineers for designing their fine lenses !

thank you for reading and now I will retire to my morning coffee.

I suggest that over your cup of coffee you learn something about optics and sensor technology, so that you can get it just a bit right next time.

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Bob

OP gsergei Contributing Member • Posts: 841
After reading your " Sensors measure charge not current"
6

I am positive you have never finished your high school.

Overall - a superb technical illiteracy. Can't argue with you, sorry.

BTW, the term "charge" is used for capacitance and is measured in Culons or Farades as in capacitors, not light sensitive diodes output , which is voltage/current.

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