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Optics Theory - This forum is aimed towards the TECHNICAL side of photographic OPTICS THEORY. There will be some overlap by camera/manufacturer, but this forum is for the heavy duty tech discussions. This is NOT the place to discuss a specific lens or lens line, do that in the appropriate forum. This is the forum to discuss optics or lenses in general, to learn about the tech behind the lenses and images. IF you have a question about a specific lens, post it in the forum about that type of camera, NOT HERE.

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Old 06-20-2018   #81
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Originally Posted by retinax View Post
You guys realize that we still use those same eyes to look at photographs?
And you do realize that a photograph is not real life?
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Old 06-20-2018   #82
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Originally Posted by oldwino View Post
And you do realize that a photograph is not real life?
Hmm the photographs in my life seem pretty real. Sorry if that still sounds a bit condescending. I'm in the habit of trying to provoke people to elaborate on their reasoning by poking questions and pointing out flaws, which often doesn't go down well, understandably...

But I think my concern is valid, if we use the same eyes with their optical flaws to look at pictures, why would it help to incorporate these flaws in the pictures, even if the premise that they make things look nicer holds true? Because more of them is better or?

Last edited by retinax : 06-20-2018 at 05:40. Reason: typo
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Old 06-20-2018   #83
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Originally Posted by retinax View Post
Hmm the photographs in my life seem pretty real. Sorry if that still sounds a bit condescending. I'm in the habit of trying to provoke people to elaborate on their reasoning by poking questions and pointing out flaws, which often doesn't go down well, understandably...

But I think my concern is valid, if we use the same eyes with their optical flaws to look at pictures, why would it help to incorporate these flaws in the pictures, even if the premise that they make things look nicer holds true? Because more of them is better or?
Because, I think, that our flawed eyes “see” a representational view of the world, and certain lenses seem to “see” the world in the same way. So the resulting photo, a 2D version of our 3D world, is somehow more “lifelike”.

I’m not a huge Garry Winogrand fan, but his assertion that he photographs something to so how it looks like in a photograph is right on.
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Old 06-20-2018   #84
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This thread is veering dangerously close to "what is art?".
I am still waiting for a near-consensus on which lens (that will fit my M2) (that I can afford) will POP.
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Old 06-20-2018   #85
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This thread is veering dangerously close to "what is art?".
I am still waiting for a near-consensus on which lens (that will fit my M2) (that I can afford) will POP.
Put them in the microwave with some butter and they’ll ‘POP’!
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Old 06-20-2018   #86
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Rather than a debate about what is art, this is veering more towards what is reality. What we see is not really what is there in front of us, it's simply how we view reality. With two eyes that see the external world at a different angle than the other, our brain has to put the two images together to come up with what we see. Fortunately, most of us see reality pretty much the same as someone else sees it, but not always. And this certainly doesn't mean that we see things as they are. Another type of being like a cat, dog, etc sees the world differently than we do. Which is more real than the other?

If we saw things as they really are, then objects would not get bigger and bigger as we get closer. That is impossible. The size remains constant, but in order to give us depth perception, our brain creates the illusion that things are getting bigger as we move closer to them. That doesn't really happen. There are many visual illusions that we take as fact because that's the way our brains have evolved. If they had evolved in a different manner, then what we see would look different than it does now.

NONE of what we see is actually there in the manner that we see it, so to think it's reality is a mistake. It's simply what we have agreed by consensus to call reality. Our human ears cannot hear certain sound frequencies, but that doesn't mean the sound isn't there. It's the same with our eyes. There are lots of things that are beyond the range of our optical capability, but that doesn't mean those things aren't there. And optical illusions are the clear perception of things that are NOT there. If you take a pencil, hold it in the middle with two fingers, and shake it up and down, it clearly appears to bend. That doesn't mean it really bends. If you photograph a spinning top with a high speed shutter it no longer blurs but appears to be clearly defined, while our eyes absolutely see a blurry, spinning image. Which is "real"? None of it!

Anyway, it's obvious to my eyes that many of the lenses I've owned that had lots of elements occasionally made photos that had lots of "pop" and a decided 3-D look if used in a manner that would give that effect. It just is what it is. Or from a different perspective, it clearly isn't what it is, it's simply what I see.
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Old 06-20-2018   #87
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Quote:
Originally Posted by davidnewtonguitars View Post
This thread is veering dangerously close to "what is art?".
I am still waiting for a near-consensus on which lens (that will fit my M2) (that I can afford) will POP.
Where is no such thing. Cheap and with POP.
Where are some lenses with not flat rendering. No cheapies, but not ebay Leica prices.
Ultron 35 1.7, you could find white LTM under 500 and VM under 1000.
Biogon C 35. Well under 1000, white is available.
Summarit-M 35 2.5 slightly above 1000.
I have Summarit and very often after looking at prints from negatives taken with this lens I'm saying YES, which is in some languages POP-POP-POP.
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Old 06-20-2018   #88
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Originally Posted by Steve M. View Post
Rather than a debate about what is art, this is veering more towards what is reality. What we see is not really what is there in front of us, it's simply how we view reality. With two eyes that see the external world at a different angle than the other, our brain has to put the two images together to come up with what we see. Fortunately, most of us see reality pretty much the same as someone else sees it, but not always. And this certainly doesn't mean that we see things as they are. Another type of being like a cat, dog, etc sees the world differently than we do. Which is more real than the other?

If we saw things as they really are, then objects would not get bigger and bigger as we get closer. That is impossible. The size remains constant, but in order to give us depth perception, our brain creates the illusion that things are getting bigger as we move closer to them. That doesn't really happen. There are many visual illusions that we take as fact because that's the way our brains have evolved. If they had evolved in a different manner, then what we see would look different than it does now.

NONE of what we see is actually there in the manner that we see it, so to think it's reality is a mistake. It's simply what we have agreed by consensus to call reality. Our human ears cannot hear certain sound frequencies, but that doesn't mean the sound isn't there. It's the same with our eyes. There are lots of things that are beyond the range of our optical capability, but that doesn't mean those things aren't there. And optical illusions are the clear perception of things that are NOT there. If you take a pencil, hold it in the middle with two fingers, and shake it up and down, it clearly appears to bend. That doesn't mean it really bends. If you photograph a spinning top with a high speed shutter it no longer blurs but appears to be clearly defined, while our eyes absolutely see a blurry, spinning image. Which is "real"? None of it!

Anyway, it's obvious to my eyes that many of the lenses I've owned that had lots of elements occasionally made photos that had lots of "pop" and a decided 3-D look if used in a manner that would give that effect. It just is what it is. Or from a different perspective, it clearly isn't what it is, it's simply what I see.
Not going into the philosophical discussion deeper for now, although it's interesting, but the issue of perspective I think you got wrong. Think of the camera obscura, it too represents further objects smaller. That's not in our brains. It's a consequence of projecting three dimensions onto a plane. I don't think there's an alternative.
Edit: P.S. I nearly got my brain in a knot trying to figure this out when I was a kid. If you know the excellent German children's book Jim Button, you know why.
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Old 06-20-2018   #89
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Quote:
Originally Posted by davidnewtonguitars View Post
This thread is veering dangerously close to "what is art?".
I am still waiting for a near-consensus on which lens (that will fit my M2) (that I can afford) will POP.
The Summaron 35/2.8. That will "POP".
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Old 06-20-2018   #90
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Originally Posted by Steve M. View Post
Rather than a debate about what is art, this is veering more towards what is reality.
That's a nice change, the thread started with a proposed theory that had nothing to do with reality!
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Old 06-22-2018   #91
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Sticking with the Nikkor 50mm f/1.4 AF-D. Classic 7 element, 6 group 50/1/4. Nothing more (or is there?). Nothing less. Light, well-made. Auto focuses. Nikon coating. Current production lens for 23 years now, introduced in 1995. There's a reason for that. Incidentally, its DXO score is the same as the newest Nikon G 50/1.4.

Let's go over to DXO and compare it to the similarly spec'd Zeiss Milvus:

Milvus
Price: $1200
Score: 35
Sharpness: 20 P-Mp
Distortion: .4%
Vignetting: -1.6
CA: .8 um
TRANSMISSION: 1.7

Nikon
Price $386 (but less than $200 minty used)
Score: 32
Sharpness: 16
Distortion: .4%
Vignetting: -1.4
CA: .9 um
TRANSMISSION 1.4

The newish $1200 Zeiss is sharper (at 1.4 mainly, and in the corners and borders nobody cares about, I'm sure) and vignettes less (does this even matter s'much in the digital era, really?)

However, the Zeiss has a t-stop value of 1.7. Like the Sigma Art 1.4, this is a horrid transmission score, while Nikon's is perfect 1.4 in, 1.4 out. No loss of light -- and the information that light is carrying, via I/O processing. The Milvus is another overcorrected 10 element lens that only transmits 82% of the light it captures to the sensor, "losing" 18% of the information along the way. Another lens to appease the DPReview MTF chart gods that sacrifices overall fidelity to win the sharpness wars, which is the new megapixel wars for lenses.

Plus none of the Zeiss lenses even autofocuses. (Perish the thought, right?) Welp I like autofocus. It's faster and more convenient. Must be nice for the Zeiss (and Leica) engineers not having to worry about such things as cramming gears, motors, electronics and firmware into a lens and make a MODERN fast/accurate objective that actually can autofocus. Imagine what the "Milvus" would cost if they did! But they better watch out. Samyang is putting out some pretty nice manual focus lenses these days for 1/2 the Zeiss price.

Now let's compare the lowly mass-produced (for 23 years) Nikon to the Leica Summilux M. DXO doesn't have a rating for that lens, so we head over to Photodo:

Nikon Photodo MTF score: 4.2
Leica Summilux M MTF score: 4.2

A tie! Did I mention the Nikon has autofocus? (But the Leica does have that "buttery smooth" manual focus ring, an engineering marvel! So there's that...)

Finally, fwiw, take it with a grain, enter the search term "lenses with best microcontrast" and you'll get a box straight-away, from which this is cut-n-pasted:

Nikkor AF 50mm 1.4D.
Nikkor AF 35mm 2D.
Voigtlander SLII 58mm 1.4 Nokton.
Zeiss ZF2 35mm 2.0 Distagon.
Nikkor Ai-S 50mm 1.4.
Voigtlander SLII 58mm 1.4 Nokton.
Nikkor Series E 135mm 2.8.

Obviously others are seeing what I am seeing.

Oh -- and nobody really cares about "bokeh" or how it looks. Bokeh is to be ignored -- that's the whole point of it, and I've never observed bokeh, even the allegedly "worst" based on internet bokeh raters to be "distracting" or "bad". Any cheap telephoto lens shot zoomed out with the subject close in will produce "amazing" bokeh better than any Zeiss or Leica 50. Shoot with a cheap Tamron zoom if that's your thing.
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Old 06-22-2018   #92
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Aren't we past the time when you tell us this thread was meant as a joke?
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Old 06-22-2018   #93
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Originally Posted by NickTrop View Post

However, the Zeiss has a t-stop value of 1.7. Like the Sigma Art 1.4, this is a horrid transmission score, while Nikon's is perfect 1.4 in, 1.4 out. No loss of light
You are claiming the 50mm f1.4d is the best based on one specification and then using a spec that is clearly wrong for the 1.4d.

What you continue to claim about the light transmission in the Nikon lens is not possible, it reflects light. And you continue to ignore that. As well as the tested data that shows the 50 f1.4d has about 91% light transmission. Not that that spec means anything like what you think it does.

If you want to use data to try and 'prove' your hypothesis you can't pick and choose to ignore data that disagrees with your hypothesis.

There are plenty of comparisons between Nikon 50mm available online. And they do much more than base this on a couple of specs. For example:

https://medium.com/vantage/comparing-nikon-s-cheap-50mm-prime-lenses-653bb2b46c2c

https://nikonrumors.com/2011/11/03/s...y-jordan.aspx/

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Old 06-22-2018   #94
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You are claiming the 50mm f1.4d is the best based on one specification and then using a spec that is clearly wrong for the 1.4d.
Is it wrong? The new Nikon G series 50/1.4 is rated at 1.5 t-stops with one more glass element (8) for the light to pass through. Perhaps this is a spec Nikon focuses on, while the others are trying to outdo each other in meaningless (beyond a certain point) resolution tests? Did DXO screw up twice? Or is there confirmation bias and cognitive dissonance happening here? I say the D-series 1.4 has a very high transmission score and that 1.4 = 1.4 due to rounding. Yes, there are surface-to-air regions but it likely loses a little less than 0.10, hence the 1.4 spec. Now that "Thom" guy doesn't like this particular Nikon s' much, complaining about a center hot spot "especially shooting IR film" at f16 that I've never seen and never shoot at and haven't shot IR film in 15 years. But he's a zoom guy anyway. What's he know from primes?

Do note that I do not cite quantitative scores as "be all and end all" but am trying to reduce subjectivity and make it as apples-to-apples as possible.

Basically I regard Zeiss and Leica glass as classic Veblen goods:

"Veblen goods are types of luxury goods for which the quantity demanded increases as the price increases, an apparent contradiction of the law of demand. Consumers actually prefer more of the good as its price rises, and the result is an upward sloping demand curve." -- Wikipedia entry

If Veblen goods are your thing? Go for it!
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Old 06-22-2018   #95
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F-stop is a rounded off marketing tool. So a lens with an advertised f-stop of 1.4 might actually be 1.5 or 1.6, at which point a t-stop of 1.7 is not that much different.
All of this is also dependent on how much of the frame is used in the t-stop measurements. Or, to put it another way, do you know how much vignetting is taken into the t-stop measure? One stop of vignetting could easily lead to a half stop reduction in transmission over the whole frame.
When you stop the Nikkor down to f/2 the t-stop value drops to around 2.0! That’s right, you lose half of all that pop information carried by the light. Even worse is the 70-200/2.8 Nikkor wide open doesn’t even have a t-stop value of 2.0! That’s why it sucks.
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Old 06-22-2018   #96
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A picture is worth a thousand words. Not many pictures here.

When intellectually discussing "something" you have to define what you are discussing. No one is saying what "Pop" is. Saying "It looks more 3D...." isn't saying anything.

Here is what I'd like. Someone set up a STILL LIFE, and show me how one lens exhibits more "pop" than another. Both with the exact same subject, lighting, focal length. Then we can dissect the proverbial "pop", if there really is any with any lens.

I watched the Cooke vs Leica cinema vid, and I still can't see it. When the speaker says "see how more rounded the subject looks....see how the wall in the back is flatter...blah" What? Where? Am I the only one that wants to say The King Has no Clothes!?
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Old 06-22-2018   #97
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F-stop is a rounded off marketing tool.
No. It's not. It's a standard unit of measure that describes the light-gathering ability of a lens for subjects focused at infinity, though the "infinity" part of the equation is largely ignored today. It's no more a "marketing tool" than shutter speed. It was defined in 1867 by Sutton and Dawson. It is calculated thusly:

N= F/D

Where F = focal length, and D is the diameter of the aperture at its widest.

I bet it's rounded because if this division results in an irrational number, the size of lens barrels would become quite unwieldy or the print so small so as to be illegible. By the way, your eye has an f-stop range of 2.1 to 8.3.
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Old 06-22-2018   #98
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A picture is worth a thousand words. Not many pictures here.

When intellectually discussing "something" you have to define what you are discussing. No one is saying what "Pop" is. Saying "It looks more 3D...." isn't saying anything.

Here is what I'd like. Someone set up a STILL LIFE, and show me how one lens exhibits more "pop" than another. Both with the exact same subject, lighting, focal length. Then we can dissect the proverbial "pop", if there really is any with any lens.

I watched the Cooke vs Leica cinema vid, and I still can't see it. When the speaker says "see how more rounded the subject looks....see how the wall in the back is flatter...blah" What? Where? Am I the only one that wants to say The King Has no Clothes!?
I too would like to see more examples. My mind is mostly made up at this point, and this isn't any kind of mysterious phenomenon, but a simple property of lenses. I'd love to have my mind changed.

I couldn't see anything in the Cooke vs Leica video that would make me want to spend money to buy the more expensive lens. I watched the video on a connection that is not very fast, so I'm sure compression removed some of the distinctions. This kind of hairsplitting just bothers me sometimes. I see the differences, but the preference of one over the other is often faddish.
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Old 06-22-2018   #99
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No. It's not. It's a standard unit of measure that describes the light-gathering ability of a lens for subjects focused at infinity, though the "infinity" part of the equation is largely ignored today. It's no more a "marketing tool" than shutter speed. It was defined in 1867 by Sutton and Dawson. It is calculated thusly:

N= F/D

Where F = focal length, and D is the diameter of the aperture at its widest.

I bet it's rounded because if this division results in an irrational number, the size of lens barrels would become quite unwieldy or the print so small so as to be illegible. By the way, your eye has an f-stop range of 2.1 to 8.3.
So you think a f1.45 lens wouldn't be sold as an f1.4 lens? You know that a 50mm lens doesn't have a 50mm focal length as well. Likewise, until modern electronic shutters, 1/500s wasn't actually that fast.

There's a reason that T stops are used in cinematography. It's because they're an actual measurement of the light transmissibility of the lens, which historically has been incredibly important for a medium which consists of spliced segments of film cut from many scenes. They can't rely on a manufacturer's statement that the lens is f1.4 to mean anything.

Fortunately, for still photography, with the latitude available in film and digital sensors, a few percent fudge factor on the largest aperture doesn't matter.
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Old 06-22-2018   #100
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What's to stop Nikon from producing a lens with an f stop of 1.2-1.3 or so, and saying it's a 1.4 so the T stop is 1.4? Without technically taking apart a lens who is to know. I sincerely doubt that Nikon's lens is f1.4 with a T stop of 1.4...

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Old 06-22-2018   #101
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Originally Posted by mich rassena View Post
So you think a f1.45 lens wouldn't be sold as an f1.4 lens? [...] They can't rely on a manufacturer's statement that the lens is f1.4 to mean anything.

Fortunately, for still photography, with the latitude available in film and digital sensors, a few percent fudge factor on the largest aperture doesn't matter.
Right. The f-stop value IS a measurement for the amount of light that a lens captures in the front end of the I/O process. It is not an estimate. It is an exact calculation that is the same for all lenses that was developed in 1897 iirc. However, the lens is an I/O device. The elements, coatings, surface to glass areas are all parts of the internal process of that I/O process that results in light and information loss when the "processed light" exits the I/O device (lens) through the rear element. A lens is a device that processes light. That process "robs" information carrying light to some degree, which varies from lens to lens.

The light that actually hits the film plane or sensor is the "T-stop value". Yes, it is important in cinematography, which is why cine lenses measure light in more accurate t-stops than f-stops (and cine lenses don't have click stops, etc...)

However, the difference or ratio between t-stop and f-stop is also important to still photographers, I argue, and is overlooked. A lens, like the Sigma Art (and many others) may have a t-stop value of 1.7 on a 1.4 lens. You may look at this value difference and shrug, it's only .3. However, if you calculated this as a percentage, this difference is more substantial as the additional corrective elements in this lens over traditional/classic designs for a 50 results in only 82% of the light captured as INPUT in this lens being transmitted to the sensor/film plane and the balance -- 18%, being lost in the "process", and never making its way to the sensor.

My understanding is this loss affects some frequencies more than others (the blue spectrum) and affects microcontrast but not resolution or detail data. I argue that the loss of microcontrast is what attenuates overall fidelity and attenuates "3D pop" of an image.

A "poppy" lens is, indeed, the lowly Nikon 50/1.4 AF-D, a classic 7 element configuration. This lens has an "at or near" 100% transmission rate according to DXO.

If you want to see examples, search this lens in Flickr (or any other low element count lenses). Another good one is the Nikon 45mm 2.8 pancake, which is a Tessar design -- 3 elements.

Here are a couple examples of the 50/1.4D that I think "pop".

https://www.flickr.com/photos/meccan...-8wVxrW-cvgLhy

https://www.flickr.com/photos/teamgr...8wVxrW-cvgLhy/
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Old 06-22-2018   #102
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Nick a small correction the Tessar has 4 elements not 3, also maybe Nikon was honest enough and actually used the T Stop instead of F-Stop. I agree the difference between F and T stop can be quiet substantial. But 7 elements ist not really a low element count lens as far as prime lenses go. For a Zoom lens it would but a 6 to 7 elements prime lens is pretty much the standard. Most of them being a double Gauss variation. 4 Elements is enough to correct most optical faults from a lens design point of view.
Also in cinematography you light for the T-stop you want, the shutterspeed can't be used in the same way as in still photography. You can vary the exposure by changing the angle of the shutter but this has some serious effects on the look of the image.
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Old 06-22-2018   #103
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What's to stop Nikon from producing a lens with an f stop of 1.2-1.3 or so, and saying it's a 1.4 so the T stop is 1.4? Without technically taking apart a lens who is to know. I sincerely doubt that Nikon's lens is f1.4 with a T stop of 1.4...

Joe
I have already addressed this. That's the DXO score. Look it up to verify, be my guest. I say there is probably some light loss but it's minimal and this 1.4 t-stop value is due to rounding. The actual number may be something like 1.44 (or something). The newer G-series has a 1.5 t-stop rating, also excellent, with one more element than its classic D-series counterpart. And this has been measured by a third-party, DXO, not Nikon. And what's to stop Nikon? I suppose they could but it's a standard measurement, and nobody buys a lens (nor seems to care other than me, really) based on differences between f-stop and t-stop values.
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Old 06-22-2018   #104
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Nick, thanks for starting this thread, and for defending it in the face of some unfriendly criticism. I can't have an opinion whether your theory is true or false as I understand very little of optics, but like the old saying "I may not be able to define it, but I know it when I see it" applies, and because of this thread, I will know a little more of what I am looking at.
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Old 06-22-2018   #105
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Originally Posted by goamules View Post
When intellectually discussing "something" you have to define what you are discussing. No one is saying what "Pop" is. Saying "It looks more 3D...." isn't saying anything.
Here is what I'd like. Someone set up a STILL LIFE, and show me how one lens exhibits more "pop" than another. Both with the exact same subject, lighting, focal length. Then we can dissect the proverbial "pop", if there really is any with any lens.
The nuts behind "glass is evil" have done that.

I think you will convert to the church when you see how much "pop" the 6 element lens have over 13 element lens (one picture was slightly altered to have roughly the same center exposure, corner fall-off and fov):

...

You can't see it? Just as well, not everybody has the eye that is required to see the "slower photons" (I'm not making that up!) and the havoc and flatness they create.
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Old 06-22-2018   #106
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The nuts behind "glass is evil" have done that.

I think you will convert to the church when you see how much "pop" the 6 element lens have over 13 element lens (one picture was slightly altered to have roughly the same center exposure, corner fall-off and fov):
...

You can't see it? Just as well, not everybody has the eye that is required to see the "slower photons" (I'm not making that up!) and the havoc and flatness they create.
Brilliant post! That link is simply hilarious reading. ... I wonder if there are any eye exercises that can let me see the slower photons too.
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Old 06-22-2018   #107
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Originally Posted by NickTrop View Post
Is it wrong? ...... Or is there confirmation bias and cognitive dissonance happening here?
Yes to both. It isn't possible for that lens to have 100% light transmission. Go look at the very best (likely extremely expensive) optical glass Schott mades. That is a single thin layer of glass that isn't doing anything else to the light and it doesn't have 100% light transmission. That thinking some couple of hundred dollar lens with many more elements beats that is absurd. You are looking at one single (wrong) spec and using it to try and confirm your hypothesis. That is the definition of confirmation bias.

100% transmission would mean the glass was invisible, you couldn't see it as no light would be reflecting off it. Clearly that isn't the case.

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I say the D-series 1.4 has a very high transmission score and that 1.4 = 1.4 due to rounding.
No, you said multiple times it had 100% light transmission and perfect transmission with no information loss. That isn't possible. The spec you keep repeating is wrong and a loss of brightness doesn't mean what you are implying. Stop down 1 stop and light transmission is cut in half. But almost every lens on the planet will improve optically. Think about that. Stopping down, literally passing less light through a lens from input to output, makes it objectively better in many measurable areas as well as subjectively better in sharpness, contrast and even lighting (vignetting). If reduced light transmission equaled information loss that would not be possible.

The 1.4d has about 91% transmission (for green) and its transmission is uneven across the visible spectrum. It has more color shifts that some other lenses.

I understand wanting to try to quantify this but you are trying to quantify something that is personal preference. That means it is a subjective opinion. If you like the 1.4d fine, it has some characteristic that you prefer. No problem.

Where a problem comes into play is when people try and justify or assume their preference is because some technical aspect of the product might be 'perfect' and then go out and try and prove that without much knowledge about all the other variables at play in the product and their preferences related to it.

If you like the 1.4d great, enjoy it. It isn't because of perfect light transmission.

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Old 06-22-2018   #108
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Quote:
Originally Posted by brbo View Post
The nuts behind "glass is evil" have done that.

I think you will convert to the church when you see how much "pop" the 6 element lens have over 13 element lens (one picture was slightly altered to have roughly the same center exposure, corner fall-off and fov):

...

You can't see it? Just as well, not everybody has the eye that is required to see the "slower photons" (I'm not making that up!) and the havoc and flatness they create.
I feel like there must be a bit of sarcasm in your post, but I'll break down what I saw when looking at the article.

In the right image, the camera is closer to the subject than in the left.

If you compare the image of the two heads cropped, where the article says "And there you have it: rounder cheeks, rounder neck, unstretched." you'll find that in the photo on the left, the head is closer to the camera. So, you get a shallower depth of field. Note the objects in the background. The perspective, the arrangement between objects in the foreground and background should not change if the entrance pupil is in the same spot. You could use an 18mm lens and compare a crop from that photo to one taken with a 600mm lens and they should align perfectly, as long as the camera hasn't moved. So something was done incorrectly. Being closer to the camera makes the head on the left appear larger. Putting the images side by side greatly exaggerates the effect. In fact there are a number of well-known optical illusions which rely on objects being compared this way.

For the curious, take the two images and overlap them in Photoshop and switch off the layer visibility and go back and forth. It should be very clear what is happening.

Also that whole business about stretch to the left. Being closer to a subject exaggerates the difference between objects which are near and far. Even the lips and nose of the sculpture will differ in presentation of they are different distances from the camera. Objects further away from the camera appear flatter. There is a typical portrait distance, which happens to coincide with fitting well with the field of view of a 85mm lens on full frame. Get too close, and the nose bulges out and the ears go away.

But again, overlay the two images, compare them. You'll see the differences are trivial.

It's not the camera or the lens, it's where you stand. It's frustrating to have to use the phrase "not even wrong" to describe this article, but there you are.
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Old 06-22-2018   #109
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Quote:
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No. It's not. It's a standard unit of measure that describes the light-gathering ability of a lens for subjects focused at infinity, though the "infinity" part of the equation is largely ignored today. It's no more a "marketing tool" than shutter speed. It was defined in 1867 by Sutton and Dawson. It is calculated thusly:

N= F/D

Where F = focal length, and D is the diameter of the aperture at its widest.

I bet it's rounded because if this division results in an irrational number, the size of lens barrels would become quite unwieldy or the print so small so as to be illegible. By the way, your eye has an f-stop range of 2.1 to 8.3.
It's rounded, fudged, and pushed as far as it can be to either a) be the "fastest" or b) fit in with full, 1/2 or 1/3 stop accepted values.

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Right. The f-stop value IS a measurement for the amount of light that a lens captures in the front end of the I/O process. It is not an estimate. It is an exact calculation that is the same for all lenses that was developed in 1897 iirc.
No, it's not a measurement, it's an ideal theoretical calculation, as you say above.

The light that actually hits the film plane or sensor is the "T-stop value". Yes, it is important in cinematography, which is why cine lenses measure light in more accurate t-stops than f-stops (and cine lenses don't have click stops, etc...)

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However, the difference or ratio between t-stop and f-stop is also important to still photographers, I argue, and is overlooked. A lens, like the Sigma Art (and many others) may have a t-stop value of 1.7 on a 1.4 lens. You may look at this value difference and shrug, it's only .3. However, if you calculated this as a percentage, this difference is more substantial as the additional corrective elements in this lens over traditional/classic designs for a 50 results in only 82% of the light captured as INPUT in this lens being transmitted to the sensor/film plane and the balance -- 18%, being lost in the "process", and never making its way to the sensor.

My understanding is this loss affects some frequencies more than others (the blue spectrum) and affects microcontrast but not resolution or detail data. I argue that the lost off microcontrast is what attenuates overall fidelity and attenuates "3D pop" of an image.
The difference between T and F stops is only important if you don't use a TTL meter and only if it is big enough to result in a botched exposure.

Correct!! The loss of transmission through a lens of course effects some frequencies more that others. Frequency = colour, and any reflection is a loss. If you look at your 1.4/50 AF-D you'll see that it's coated in purple and amber I believe. You can see those colours because they are reflected while others are not. Reflected = not transmitted, so if you can see a coating (or any part of the glass) then it doesn't have 100% transmission. The loss is specifically in the colours you see reflected.

So, micro contrast and 3D pop. Depending on your definition if 3D pop, micro contrast has an influence, but also how the contrast changes with respect to the focal plane and a whole host of other things. Contrast, micro and global, is important. But, it has nothing to do with T stop or F stop. Nothing.

Now I see the misconception. Blue light. Blue has a shorter wavelength, so it must feature in micro contrast more than red, whose wavelength is longer. This is incorrect.
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Old 06-22-2018   #110
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Quote:
Originally Posted by goamules View Post
A picture is worth a thousand words. Not many pictures here.

When intellectually discussing "something" you have to define what you are discussing. No one is saying what "Pop" is. Saying "It looks more 3D...." isn't saying anything.
+1 +1 +1

Whenever these conversations pop up, it soon becomes clear that different folks mean different things by "Pop", or 3-D, or plasticity, or roundedness. This is usually clearest when someone does post a photo illustrating what they take "Pop" to be about.

After looking at many of these threads, IMO, the argument goes on because people then argue about causes of different phenomena as though those phenomena were one and the same.

I, too, would love to see a set of photos illustrating these implicit definitions. Not so much because I think that would get us agreeing about the causes, but because we might get closer to agreement on nomenclature.

For example, some people showing a photograph they associate with POP show a photo taken at relatively wide apertures with a background in the distance (out of focus) often taken with a lens exhibiting vignetting.

This is not what I mean when I say 3D which often involve one of several situations: 1) the interwoven above ground roots of a tree, often with no out of focus portion, 2 portraits, 3) large woods, or high cathedral interiors, or 4) both rural and urban landscapes with receding lines.

Clearly the last two owe at least part of the 3D aspect to lighting direction and perspective effects in the subject. Not having seen enough such photos, I am not ready to conclude that ALL 3D impression is a result of lighting and subject characteristics.

Anybody interested in generation a group of photos with the characteristic they illustrate: 3d, POP, dimensionality, roundedness, plasticity, etc?
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Old 06-22-2018   #111
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It's just distortion.

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Old 06-22-2018   #112
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It's just distortion.
But, which one “pops”? It’s so obvious one just can’t decide!
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Old 06-23-2018   #113
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Ok folks, there is a difference. If you can't see it - too bad. Go to bed, dream of your Leica, Zeiss or Nikkor and sleep well. If you are using a cheap or average monitor with poor colour you won't appreciate the tonal differences. If you do see the difference, they are very minor. Just go, take photos and create art. The FIFA world cup is on, nukes haven't blown us up yet, tomorrow is another day. I might go and use my CV 21/4 with some Fuji SS 400 on my iiif. This could be nice! ;D
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Old 06-26-2018   #114
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Can someone explain why nowadays there is increasing number of multi-focal lenses with good wide apertures, such as olympus 12-40 f2.8? Or is it my perception? Has the technology advanced? To my knowledge it was hard to obtain single wide aperture for multi focals in the past. So in defense of the OP's main point here, they are supposed to be inferior to old low element count lenses such as my zeiss 45mm f2 for contax g? (I can hear people saying "inferior in what sense?", I dont know lets say its resolution power).
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Old 06-26-2018   #115
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Quote:
Originally Posted by LeicaFoReVer View Post
Can someone explain why nowadays there is increasing number of multi-focal lenses with good wide apertures, such as olympus 12-40 f2.8? Or is it my perception? Has the technology advanced? To my knowledge it was hard to obtain single wide aperture for multi focals in the past. So in defense of the OP's main point here, they are supposed to be inferior to old low element count lenses such as my zeiss 45mm f2 for contax g? (I can hear people saying "inferior in what sense?", I dont know lets say its resolution power).
In short, yes. Technology has advanced that far. Advances in computer simulations and designs, advances in manufacturing and repeatedly being able to make something to within small tolerances, advances in glass and glass-plastic hybrid element mouldings for highly aspherical elements, and lastly, advances in computation on the raw data in camera to reduce distortions and vignetting and such.

As an example, the lens elements in your phone are so highly aspherical that they would have been impossible to manufacture a decade or so ago, now they cost a few cents. See for example https://images.anandtech.com/doci/67...tation.013.png
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Old 06-26-2018   #116
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In short, yes. Technology has advanced that far. Advances in computer simulations and designs, advances in manufacturing and repeatedly being able to make something to within small tolerances, advances in glass and glass-plastic hybrid element mouldings for highly aspherical elements, and lastly, advances in computation on the raw data in camera to reduce distortions and vignetting and such.

As an example, the lens elements in your phone are so highly aspherical that they would have been impossible to manufacture a decade or so ago, now they cost a few cents. See for example https://images.anandtech.com/doci/67...tation.013.png

That (what you linked) is a pretty low element count lens. In earnest though I wonder when these complex surfaces will show up in lenses for larger sensors. That could indeed mean less elements.
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Old 06-26-2018   #117
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Admittedly I have only skimmed this so far but I see no mention of veiling flare. In the early days of Kodachrome it was not particularly unusual to prefer uncoated lenses, or to omit lens hoods, so that veiling flare (non-image-forming diffuse light) flattened contrast by "filling" the shadows. More light in the shadows = higher film speed, the equivalent of a faster lens.

In the 1930s it was famously the case that fast Leica lenses had higher resolution but less contrast (more lens groups -- not necessarily more lens elements) while Zeiss had more contrast but less resolution; this is why 50 Sonnars are 3-group lenses ( 6 glass/3 group for the f/2 and 7 glass/3 group for the f/1.5: fewer air/glass surfaces). Coating bought a lot more contrast to such lenses as the Xenon (7 glass, 5 group) and its successor the Summarit (7/5 again).

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Old 06-26-2018   #118
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No one also mentions about the content of the glasses (e.g.REE contents) or their quality such as the presence of micro bubbles or not. How does it compare past and modern times glasses? I heard from my father that during second world war, Russia took away a lot of raw zeiss or leica glasses, which were aged to get rid of bubbles, and later used those in their early russian lenses and hence the quality of early Jupiters are better (?). Has anyone heard of that story?
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Old 06-26-2018   #119
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Quote:
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No one also mentions about the content of the glasses (e.g.REE contents) or their quality such as the presence of micro bubbles or not. How does it compare past and modern times glasses? I heard from my father that during second world war, Russia took away a lot of raw zeiss or leica glasses, which were aged to get rid of bubbles, and later used those in their early russian lenses and hence the quality of early Jupiters are better (?). Has anyone heard of that story?
No, and it's not true anyway. You can't "age" glass to "get rid of bubbles", and the impact of small bubbles on image quality is immeasurably trivial.

Sorry, but not sure about what you mean by REE.

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Old 06-26-2018   #120
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Quote:
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No one also mentions about the content of the glasses (e.g.REE contents) or their quality such as the presence of micro bubbles or not. How does it compare past and modern times glasses? I heard from my father that during second world war, Russia took away a lot of raw zeiss or leica glasses, which were aged to get rid of bubbles, and later used those in their early russian lenses and hence the quality of early Jupiters are better (?). Has anyone heard of that story?
There are trade-offs with glass composition. We have newer glass types, but on the other hand toxic metals are no longer allowed, so I'm not sure if it's better or worse. In many ways modern lens designers have their hands tied compared to their predecessors.

Already in the early 1900's glass making was well established for those who paid for it, bubbles were not an issue for established lens makers.

Case in point is the Hasselblad SWC. Early models had lead containing glass (up to the CF). The 905SWC (CFi lens) had to eliminate the lead for environmental reasons, so newer glass types were chosen and the lens recomputed to compensate. It's considered to be not as good and indeed the MTF charts tell the same story (see links).
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