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Crazy disinformation about DOF, 4/3 f-stop vs 35mm, microlenses

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odl said:
Great Bustard said:
OK, well, this is an important point -- I'm talking about the photo. As you may, or may not, have read in my entry into this thread:

So, no, the lens does not change -- no one says it does (I mean, how could it?). But the effect of the lens most certainly does change.
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But he is talking about the lens.
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Neither perspective, framing, nor DOF are properties of the lens -- they are properties of the system .

I am talking about the photo that is made with the lens and the body it is used on. What other possible interest could I have in the lens except as it pertains to the photos created with it?
odl said:
No, but that also has nothing to do with framing or perspective. How we chose to frame a subject has nothing to do with the lens. We make our framing choice regardless of the lens. Same with perspective. We can chose and lens we like for the picture. There is no point comparing two different lenses... But he isnt, he is comparing the same lens.
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As a photographer, what interest do I have in a lens except in the context of the photos it produces on the body it is used on? The lens, by itself, does not create a photo -- the system the lens is used on creates the photo, and it is how the lens performs on the system that it is used on that is the relevant matter.
odl said:
odl said:
The D40 has ridiculously poor QE:

So, absolutely, in that particular case, the more efficient sensor in the D7000 which has double that amount will result in double the light being recorded for a given exposure (and thus only 71% the apparent photon noise), which is the primary element of the noise in the photo.
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But you see, between the two, the sensor improved. Nothing more. All image quality improvements will have everything to do with the sensor and processing and nothing to do with photon shot noise which has been a constant since photography began.
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Fair point, and I don't disagree. But it is important to realize that the efficiency of the sensor has two components: QE and read noise, where the QE is the proportion of photons falling on the sensor that get recorded (and directly influences the photon noise), and the read noise is the additional noise added by the sensor and supporting hardware.
odl said:
odl said:
In other words, photon noise is dominant, but the QE of the sensor plays a role in the photon noise. However, the maximum possible QE is 100%, and the best modern digicams are hovering around 50%, so we're not going to keep on seeing doublings in performance.
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Nope, but this is performance for current technology. We may see performance gains with new tech. We will see performance with processing.
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The photon noise is the dominant source of noise in a photo (unless the photo is mainly dark, and then the read noise is the dominant source of noise). The role of the sensor in photon noise, as I said above, is the QE.
odl said:
We dont need to see ANY data about sensor efficiency. I simply makes my point, a great deal of the noise we see in imaging is sensor noise.
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It's a weird way to put it, Ab. The bulk of the noise we see is photon noise, which is from the light itself, which is made worse by the fact that the QE of the sensor is not 100% (and also the fact that the sensor is RGGB rather than each pixel recording all photons).

Usually, when one speaks of the "sensor noise", they mean the additional noise added by the sensor and supporting hardware, which is different from the photon noise.
odl said:
Oh, i know how it works, It really isnt that complex.
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It really isn't. The primary elements of noise in a photo are:
  1. the total amount of light that falls on the sensor (Total Light = Exposure x Sensor Area)
  2. the proportion of that light that is recorded by the sensor (QE -- Quantum Efficiency)
  3. the additional noise added by the sensor and the supporting hardware (read noise)
Of course, that's just luminance noise. There's also color noise which has to due with the transmissivity and transmission error of the red, green, and blue dyes in an RGGB CFA.
odl said:
It is just that you do enjoy arguing a point slightly to the left of the main subject and enjoy dictating the terms of the discussion.
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Each party always thinks that of their "opponent". ;)
odl said:
Photography remains an art, not a science,
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Art and science are not mutually exclusive.
 
neil1c2000 said:
You say tomato I say tomahto.
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Well, as evidenced by others who came into this discussion on the thread, as well as the available literature, those who say "tomahto" are in a distinct minority, and when those saying "tomahto" make comments like:

http://forums.dpreview.com/forums/read.asp?forum=1022&message=39918037

Joking aside, your statement that noise is an inherent property of the light is just wrong
That you make such statements is a real worry.

That you refuse to admit you are wrong - well that's just the way you are I suppose, but unfortunately many readers of your work here take everything you say as true and correct.

Well, let's just say that it doesn't make the case for "tomahto" appealing.
 
neil1c2000 said:
neil1c2000 said:
neil1c2000 said:
neil1c2000 said:
neil1c2000 said:
Noise is an inherent property of the light itself
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--Now that's what I call disinformation.
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That's completely consistent with your posting history. Good luck to you, too.
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And my posting future, too. And good luck to you.
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Touché. While I accept your gracious offer of luck, in general, I find I don't really need it -- knowing what I'm talking about is generally enough (depending on the audience, of course).
 
Great Bustard said:
Great Bustard said:
Plus you keep dodging the NEX7 NEX5n example, you can clearly see the better performance of one over the other. Sensor performance. Now while people say 57% efficiency is very good, we mean "for current technology".
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I don't keep dodging it -- I keep saying that I have no information on the relative efficiencies between the two sensors. And, even if the NEX7 sensor turns out to be less efficient (rather than unoptimized RAW conversion software and/or jpg engines), it's still not a given that this is due to the smaller pixels, rather than some other cause.
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Nex5n vs a77 (same sensor as Nex7):
http://forums.dpreview.com/forums/read.asp?forum=1037&message=39719198

Notice that the Nex5n was used with an adapter containg a semitransparent mirror thus equalising the light loss to the AF module in both systems.

I don't see the better performance so clearly from this example
 
Great Bustard said:
Very nice demonstration of how DOF changes with enlargement:
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yes, and it demonstrates that crop 2 has shallower dof compared to aps-c or FF if you use the same lens and enlarge the photos to identical picture size.

and, if you want to have same framing and crop therefore the FF picture and enlarge the identical frame to identical picture size, then DOF and noise will be identical.
what not will be identical is autofocustolerance and most liekly resolution.

therefore it is better to use a crop cam instead of cropping FF.

best regards gusti
 
mcabato said:
Great Bustard said:
Very nice demonstration of how DOF changes with enlargement:
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yes, and it demonstrates that crop 2 has shallower dof compared to aps-c or FF if you use the same lens and enlarge the photos to identical picture size.
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If you use the same lens from the same distance, and therefore have different framing.
mcabato said:
and, if you want to have same framing and crop therefore the FF picture and enlarge the identical frame to identical picture size, then DOF and noise will be identical.
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Yes.
mcabato said:
what not will be identical is autofocustolerance and most liekly resolution.

therefore it is better to use a crop cam instead of cropping FF.
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It's even better to use a longer focal length on full-frame than shorter on crop.

--
Lee Jay
(see profile for equipment)
 
ljfinger said:
mcabato said:
Great Bustard said:
Very nice demonstration of how DOF changes with enlargement:
Click to expand...
yes, and it demonstrates that crop 2 has shallower dof compared to aps-c or FF if you use the same lens and enlarge the photos to identical picture size.
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If you use the same lens from the same distance, and therefore have different framing.
Lee Jay said:
and, if you want to have same framing and crop therefore the FF picture and enlarge the identical frame to identical picture size, then DOF and noise will be identical.
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Yes.
Lee Jay said:
what not will be identical is autofocustolerance and most liekly resolution.

therefore it is better to use a crop cam instead of cropping FF.
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It's even better to use a longer focal length on full-frame than shorter on crop.

--
Lee Jay
(see profile for equipment)
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I do fully agree. so please finance my 5.6/800 plus teleconverter or, better, the 5.6/1200mm plus team to carry.

BR gusti
 
mcabato said:
I do fully agree. so please finance my 5.6/800 plus teleconverter or, better, the 5.6/1200mm plus team to carry.
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Why, do you already have a 400/2.8 and 600/2.8 for 4/3?

--
Lee Jay
(see profile for equipment)
 
ljfinger said:
mcabato said:
I do fully agree. so please finance my 5.6/800 plus teleconverter or, better, the 5.6/1200mm plus team to carry.
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Why, do you already have a ..... ?

--
Lee Jay
(see profile for equipment)
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you bet, but your ideas are wrong :-)
2.8/500 and 5.6/1000mm FF equivalence :-)
rgds gusti
 
mcabato said:
you bet, but your ideas are wrong :-)
2.8/500 and 5.6/1000mm FF equivalence :-)
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That is correct, and I can and have proven it both mathematically and with images, over a range from full-frame to 6.25-crop.

--
Lee Jay
(see profile for equipment)
 
noirdesir said:
Now, take a good physics book (or just Wikipedia) and look up the term shot noise. IN short, the photons in light coming from an uncorrelated light source (which includes most light sources including the sun), do not come in a perfectly even stream but in noisy stream with fluctuations. And the relative amount of these fluctuations, the variation around the mean, decrease with an increasing total number of photons. Thus more light, more photons, less variations (in relative terms), less noise in the image.
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I conducted a small experiment which demonstrates this here: http://forums.dpreview.com/forums/read.asp?forum=1037&message=39918014
 
ljfinger said:
mcabato said:
you bet, but your ideas are wrong :-)
2.8/500 and 5.6/1000mm FF equivalence :-)
Click to expand...
That is correct, and I can and have proven it both mathematically and with images, over a range from full-frame to 6.25-crop.

--
Lee Jay
(see profile for equipment)
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yes, i know, because i studed also your maths smehow :-)

rgds gusti
 
jonas ar said:
jonas ar said:
jonas ar said:
Plus you keep dodging the NEX7 NEX5n example, you can clearly see the better performance of one over the other. Sensor performance. Now while people say 57% efficiency is very good, we mean "for current technology".
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I don't keep dodging it -- I keep saying that I have no information on the relative efficiencies between the two sensors. And, even if the NEX7 sensor turns out to be less efficient (rather than unoptimized RAW conversion software and/or jpg engines), it's still not a given that this is due to the smaller pixels, rather than some other cause.
Click to expand...
Nex5n vs a77 (same sensor as Nex7):
http://forums.dpreview.com/forums/read.asp?forum=1037&message=39719198

Notice that the Nex5n was used with an adapter containg a semitransparent mirror thus equalising the light loss to the AF module in both systems.

I don't see the better performance so clearly from this example
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Thanks for that link!
 
jonas ar said:
noirdesir said:
Now, take a good physics book (or just Wikipedia) and look up the term shot noise. IN short, the photons in light coming from an uncorrelated light source (which includes most light sources including the sun), do not come in a perfectly even stream but in noisy stream with fluctuations. And the relative amount of these fluctuations, the variation around the mean, decrease with an increasing total number of photons. Thus more light, more photons, less variations (in relative terms), less noise in the image.
Click to expand...
I conducted a small experiment which demonstrates this here: http://forums.dpreview.com/forums/read.asp?forum=1037&message=39918014
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Well done, Jonas! Thanks for doing the experiment and posting the results!
 
You're welcome. I suppose it is no major surprise given the almost identical DXOmark data on the a77 and a55.
I'm looking forward to see the 55MP scaled a77 sensor in the a99 next year :D
 
jonas ar said:
You're welcome. I suppose it is no major surprise given the almost identical DXOmark data on the a77 and a55.
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Like I said earlier, I haven't been following the developments much on the new Sony cameras. But, absolutely -- if the DxOMark data shows the sensors to have almost identical performance, that would have been a clue. ;)
jonas ar said:
I'm looking forward to see the 55MP scaled a77 sensor in the a99 next year :D
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Shoot -- I'm just hoping that Canon can do something, anything, to come close to the rumored D800 which will likely have a FF version of the Sony Exmor sensor in the D7000:

http://forums.dpreview.com/forums/read.asp?forum=1032&message=39892267
 
Good lord, I didn't know what kind of a firestorm I was igniting.

A lot of good information, and a lot of...well, random diatribes fueled by guesswork about how it should work based upon opinion instead of science.

So where did I go wrong? With the DOF, I didn't consider the fact one wouldn't use the same focal length on a 4/3 as they would on an APS to take a given shot. People harped on 4/3 longer DOF at a given aperture and I called BS, but in reality they meant larger DOF at a given aperture when factoring in the different focal length used to capture a given field of view with a FF, 4/3 or APS sensor.

I know light falloff is an issue with all large glass, but blanket statements made saying aperture over f/2 is wasted on 4/3 is provable bat guano. Taking my Sigma 30mm and going from f/1.4 to f/2 causes my exposure time to double JUST LIKE IT SHOULD. If Olympus was playing games with ISO like some posters accused Canon and Nikon (and Olympus) of doing then exposure wouldn't track ISO in a perfect 1 stop ratio, and shots taken at f/2 ISO would have less noise than f/1.4.

Last but not least, image noise is all about sensor design and there are many tradeoffs, size of the sensor and size of photo sites and micro lenses is just three of thousands. I work in the semiconductor industry in a state of the art fab, this is one area in which I have firsthand knowledge.

Sorry for igniting such a wild and wooly thread...there are some hard core people here that love to rip each-other a new corn hole!
--

Give a man a match, and he'll be warm for a minute, but set him on fire, and he'll be warm for the rest of his life.
 
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