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Lens corrections equivalent to audio corrections when possible

M00ndancer

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#21
It has always been the case that prime lenses have much better boke than zooms as well as having less distortion, flare and a flatter field. Zooms are getting better but I have a big psychological problem using a zoom for anything other than snapshots of grandchildren wizzing about!
My take is also that a good prime is a lot cheaper than an "equal" zoom lens.
Most of my "good" lenses are primes. I do have three zoom lenses that I use when I don't want to carry that much.
 

M00ndancer

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#22
But everything pointed me to the Nikon 14-24.
There are extreme outliers, as always. I don't use that much wide zooms so I don't know if the Ziess lenses was really a replacement for the 14-24.
A great lens.
 
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Frank Dernie

Frank Dernie

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Thread Starter #23
Outside of the cinema industry, photographers didn't used to talk much about how out-of-focus areas looked, and lens designers didn't pay attention to it. So when a lens had nice blur, it was usually a happy accident, typically due to undercorrected spherical aberration. Nowadays, photographers care about out-of-focus performance and are willing to pay for it. This has shifted priorities in the industry.
I don't know how recently you mean but I and friends using fast lenses have been talking about boke for well over 30 years, and I know nothing of cinema photography.
If you take portraits with fast lenses any harshness in the oof area draws the eye away from the subject.
It may well be uncorrected spherical aberration in some cases but presumably there is a way of calculating and/or measuring it so one knows at the design stage.
The Canon Lens Work books over 20 years ago mentioned that the closer the meridional and saggital lines are in the MTF measurement "the more natural the background blur becomes" but does not elaborate. I have used some of their lenses and it is true the best oof rendering goes with lenses like this but some of them are certainly not burdened by uncorrected spherical aberration.
Zoom lenses are almost always poor in this respect.
As you say one of the biggest advances is in manufacturing the elements. Hand ground asphericals were monumentally expensive and had a high scrap rate, the hot pressed ones relatively cheap and easy enough to be in any lens.
Lenses which used to take hours to grind from cylindrical blanks are precision pressed to their final profile without grinding at all, and so forth.
Like so many things manufacturing technology has made what was almost impossible and expensive once cheap and quick.
This also has made the need for super sophisticated glasses largely redundant since modern coatings on multiple elements and asphericals can do the same job.
I read that the blanks of the super high refractive index glass used in the Leica 50mm F1 of 1976 had to be annealed for months before grinding.
 

paulraphael

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#24
There are extreme outliers, as always. I don't use that much wide zooms so I don't know if the Ziess lenses was really a replacement for the 14-24.
A great lens.
I have no doubt the Zeiss primes would have been great. It was just interesting / surprising to me that this zoom was a contender, and even seemed to edge out those primes a bit. I think you're right that this zoom is an outlier. It was an extreme outlier when introduced. But 13 years later, it seems this kind of performance is becoming more standard (although maybe not cheaper).

All else being equal, I'm with you ... I'd rather keep it simple and use a prime.
 
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Frank Dernie

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Thread Starter #25
The "Gestalt" of an unubtainium Leica lens
I had quite a few of those in my collection, now sold.
I would not compare them to old valves though. Some of the old Leica Zeiss and Nikon lenses are still close to sota today and would be impossibly expensive to make now.
 

paulraphael

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#26
I don't know how recently you mean but I and friends using fast lenses have been talking about boke for well over 30 years, and I know nothing of cinema photography.
That sounds about like the timeframe I'm thinking. I first heard people talking about out-of-focus rendering in the 1990s. I'd never seen lens ads from then or earlier that talked about it. Of course they might have been out there and I just missed them.

Edited to add: I do remember special-purpose lenses designed for this that went back at least to the 80s. Schneider and Rodenstock each had an expensive large format portrait lens that let you progressively de-correct spherical aberration and make smooth portraits. Nikon had something similar.
 
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Frank Dernie

Frank Dernie

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Thread Starter #27
I did too, until a few years ago when I needed a couple of very wide lenses for a project. I consulted with some architectural photographers and dove into reviews and measurements, assuming I'd end up renting Zeiss primes. But everything pointed me to the Nikon 14-24. I rented it for a day and was so impressed that I sold my most expensive lens to buy a copy of my own. It's one of the best lenses I've used of any type for any format. And it's not even state-of-the-art anymore ... I believe it was designed in 2007. There are now better zooms.

I have no idea about its bokeh, because I've never used it for that (and it doesn't come up much with ultra-wides). It's not world class at the long end of its range, and it's indeed susceptible to flare. And it weighs a ton, and has a very vulnerable bug-eye front element, so not perfect, and not right for everyone. But for my purposes I don't think a better lens was available.
I have that lens. I would not say it is better than wide primes but it is very, very good and much cheaper than buying several primes.
Boke is a non issue for wides, as you say, and it is a splendid lens.
Distortion and light fall off are correctable with digital but field curvature isn't - again not a real problem with wides at the sort of aperture likely to be used.
 
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Frank Dernie

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Thread Starter #28
That sounds about like the timeframe I'm thinking. I first heard people talking about out-of-focus rendering in the 1990s. I'd never seen lens ads from then or earlier that talked about it. Of course they might have been out there and I just missed them.
I hadn't seen it much in ads, it wasn't mainstream then perhaps.
For all the portrait photographers I know using fast lenses for the obvious reason it was as important as sharpness
 

paulraphael

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#29
I hadn't seen it much in ads, it wasn't mainstream then perhaps.
For all the portrait photographers I know using fast lenses for the obvious reason it was as important as sharpness
That may well be it. I hung out with landscape photographers and we never thought about this kind of thing. There seemed to be a time when suddenly everyone was talking about it (when I first heard "bokeh" I thought people were smoking something). Possibly that's when it shifted from a specialized engineering concern to a widespread one.
 
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Frank Dernie

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Thread Starter #30
That may well be it. I hung out with landscape photographers and we never thought about this kind of thing. There seemed to be a time when suddenly everyone was talking about it (when I first heard "bokeh" I thought people were smoking something). Possibly that's when it shifted from a specialized engineering concern to a widespread one.
Yes if there is "boke" in a landscape it is bin fodder :)
 

Wes

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#31
I hear that Panasonic's DFD system uses bokeh to achieve focus.

also, the manfs. don't give all their data to Adobe...

Bokeh is more common in "environmental" portraits, but is often sought in landscape photos as well - e.g. dew drops on flowers in the foreground etc.

I was just thinking about the photo vs. audio comparison the other day. People go wild for old Leica and Zeiss (Hassy) lenses in order to get a certain type of distortion (rendering)....
 

Wes

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#32
Perfect timing for this topic Frank... I just got ahold of a Leica Noctilux-M 50mm f/0.95 ASPH, a lens not know to be very sharp, and yet creates the most amazing photos (when you're in focus!!) and been learning about how extreme optics behave ... going to follow this thread.
you could buy a fancy power cable for that much $$
 

Wes

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#33
I think the biggest similarity between lenses and audio is the "magical thinking" that goes on in the high end of both hobbies. The "Gestalt" of an unubtainium Leica lens and the unequaled musicality of an original Western electric 300b tube for example.
The real difference here is that in photography the creator of the art piece (or the "arty" piece) is doing the magical thinking - so it is allowed if not encouraged. It may allow the consumer (viewer) to see something in a new way.

In audio, it is the accurate reproduction of a created piece (the recording) that is at issue. The consumer can 'tune' whatever he wants but magical thinking is bad. The performer or recording engineer is the analog to the photographer. So that Western 300b is just fine on a console, but a distortion in a home amp.
 
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#34
Interesting topic! As I ponder it, it seems to me that in audio the closest analogue of a lens is a microphone, as it operates upstream of the recording medium. The audio systems in our homes are more the equivalent of displays, whether screens or prints, and our listening experiences are akin to viewing experiences. In between comes data processing/editing. Some very apt analogies throughout; it's all information theory in general and capture, preservation and modification of modulation (contrasts of various types, usually now reduced to ones and zeroes) in particular.
 
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#35
Canon provides diffraction correction in it's RAW processor Digital Picture Professional when certain lenses or teleconverters are used for which Canon provides full correction profiles.

Imho that approach is excellent and produces impressive results especially for some older (supported) lenses.

https://hk.canon/en/support/8202900400
https://www.dpreview.com/forums/thread/4203324


Some marketing stuff from a retired Canon website (https://web.archive.org/web/20180225022433/http://web.canon.jp/imaging/dlo/effect/index.html):

Principle of the Digital Lens Optimizer
After passing the lens and various filters, the light has diverted from the ideal condition as it reaches the image sensor where the image will be formed. This is due to the influence of factors such as aberrations, diffraction, and the low-pass filter. If these influences can be compensated for using highly precise and specific data, the result ideally would be the original and optimal image. This is the unique principle behind the Digital Lens Optimizer. Factors contributing to optical image deterioration as the light passes through the lenses and filters in the camera were identified and converted into mathematical functions (optical transfer functions (OTF)). By applying the inverse functions to the captured image, the state of the light (image quality) can be returned to approach the state that the incident light had before entering the camera.
The factors such as aberrations, diffraction, and low-pass filter influence differ for different lenses and cameras, and they also are dependent on shooting parameters. The Digital Lens Optimizer therefore uses inverse functions that are carefully optimized and based on precise data. This makes it possible to compensate even for complex and asymmetric aberrations such as coma.

Main optical factors in image deterioration By reverting light as close as possible to how it was before entering the system by converting light transmission coefficients into functions/filters which are applied to apply to the image received by the sensor

Reduction of lens aberration
Conventional shooting practice

In photographic circles, there is a long-held rule of thumb that you should stop down slightly from maximum aperture when taking photos with a shallow depth of field for a blurry effect, or for scenes requiring a fast shutter speed. This is done to prevent a degradation of resolution in the focal area. The technique does not represent the optimal intention of the photographer, rather it is a compromise based on experience.
Produce images that are at least close to the original intention by accepting a tradeoff between photographic expression and image quality. This is a technique that is commonly used by experienced photographers.

Shooting practice with Digital Lens Optimizer
The rule about avoiding maximum aperture no longer applies when Digital Lens Optimizer is used. Because the optical characteristics will be optimized, high image sharpness with minimal aberrations can be achieved even with maximum aperture.
Whether using a fast shutter speed to capture a special moment, or a shallow depth of field for a blurry effect, the desired aperture can be chosen freely. A wider aperture also allows lowering the ISO speed for even better image quality.



Reduction of diffraction effect
Conventional shooting practice

Using a great depth of field for pan focus is one of the standard techniques of photography. But this involves a tradeoff, because small apertures could not be used if softening of the image caused by the diffraction effect was to be avoided. Conventional wisdom therefore prescribed that for better image quality, very small apertures should be avoided.

Shooting practice with Digital Lens Optimizer
The Digital Lens Optimizer is great for improving the sharpness of images taken with higher f-stops. The photographer need not worry about diffraction when shooting various kinds of scenes. The entire range, from fully open to minimum aperture, can be used, giving free reign to creativity.
Even at middle range, where image quality is generally good, aberrations and diffraction used to reduce image quality to a certain extent. With the Digital Lens Optimizer, further improvement is possible at intermediate f-stops as well.


Improvement in exposure setting flexibility
Conventional shooting practice

When shooting in the field, shutter speeds often need to be adjusted to the target. So far, this also required taking care with f-stops. If opened too much, aberrations would show up, while small apertures tended to invite diffraction. Looking for the optimum aperture that would retain sharpness while having the effect reflected in the image was one of the techniques in the arsenal of a photographer.
The question was whether to go for image quality at the expense of expressiveness, or vice versa. Even in the very moment when face to face with the object, the seasoned photographer needed to find a balance between quality and expression.

Reduces factors contributing to lower resolution across almost the entire aperture range, improving the sharpness of images taken at any aperture

Shooting practice with Digital Lens Optimizer
Because the Digital Lens Optimizer can improve sharpness over the entire aperture range, neither aberrations at full open nor diffraction when stopped down need to be a great cause for concern. Shutter speed can be at will, regardless of aperture stop.
Measures such as using an ND filter for slow shutter speeds or increasing ISO speed for high shutter speeds will rarely be called for, resulting in enhanced flexibility and responsiveness. Aperture and shutter speed cease to be a worry, allowing one's shooting style to become more creative.
 
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Frank Dernie

Frank Dernie

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Thread Starter #36
Canon provides diffraction correction in it's RAW processor Digital Picture Professional when certain lenses or teleconverters are used for which Canon provides full correction profiles.

Imho that approach is excellent and produces impressive results especially for some older (supported) lenses.

https://hk.canon/en/support/8202900400
https://www.dpreview.com/forums/thread/4203324


Some marketing stuff from a retired Canon website (https://web.archive.org/web/20180225022433/http://web.canon.jp/imaging/dlo/effect/index.html):

Principle of the Digital Lens Optimizer
After passing the lens and various filters, the light has diverted from the ideal condition as it reaches the image sensor where the image will be formed. This is due to the influence of factors such as aberrations, diffraction, and the low-pass filter. If these influences can be compensated for using highly precise and specific data, the result ideally would be the original and optimal image. This is the unique principle behind the Digital Lens Optimizer. Factors contributing to optical image deterioration as the light passes through the lenses and filters in the camera were identified and converted into mathematical functions (optical transfer functions (OTF)). By applying the inverse functions to the captured image, the state of the light (image quality) can be returned to approach the state that the incident light had before entering the camera.
The factors such as aberrations, diffraction, and low-pass filter influence differ for different lenses and cameras, and they also are dependent on shooting parameters. The Digital Lens Optimizer therefore uses inverse functions that are carefully optimized and based on precise data. This makes it possible to compensate even for complex and asymmetric aberrations such as coma.

Main optical factors in image deterioration By reverting light as close as possible to how it was before entering the system by converting light transmission coefficients into functions/filters which are applied to apply to the image received by the sensor

Reduction of lens aberration
Conventional shooting practice

In photographic circles, there is a long-held rule of thumb that you should stop down slightly from maximum aperture when taking photos with a shallow depth of field for a blurry effect, or for scenes requiring a fast shutter speed. This is done to prevent a degradation of resolution in the focal area. The technique does not represent the optimal intention of the photographer, rather it is a compromise based on experience.
Produce images that are at least close to the original intention by accepting a tradeoff between photographic expression and image quality. This is a technique that is commonly used by experienced photographers.

Shooting practice with Digital Lens Optimizer
The rule about avoiding maximum aperture no longer applies when Digital Lens Optimizer is used. Because the optical characteristics will be optimized, high image sharpness with minimal aberrations can be achieved even with maximum aperture.
Whether using a fast shutter speed to capture a special moment, or a shallow depth of field for a blurry effect, the desired aperture can be chosen freely. A wider aperture also allows lowering the ISO speed for even better image quality.



Reduction of diffraction effect
Conventional shooting practice

Using a great depth of field for pan focus is one of the standard techniques of photography. But this involves a tradeoff, because small apertures could not be used if softening of the image caused by the diffraction effect was to be avoided. Conventional wisdom therefore prescribed that for better image quality, very small apertures should be avoided.

Shooting practice with Digital Lens Optimizer
The Digital Lens Optimizer is great for improving the sharpness of images taken with higher f-stops. The photographer need not worry about diffraction when shooting various kinds of scenes. The entire range, from fully open to minimum aperture, can be used, giving free reign to creativity.
Even at middle range, where image quality is generally good, aberrations and diffraction used to reduce image quality to a certain extent. With the Digital Lens Optimizer, further improvement is possible at intermediate f-stops as well.


Improvement in exposure setting flexibility
Conventional shooting practice

When shooting in the field, shutter speeds often need to be adjusted to the target. So far, this also required taking care with f-stops. If opened too much, aberrations would show up, while small apertures tended to invite diffraction. Looking for the optimum aperture that would retain sharpness while having the effect reflected in the image was one of the techniques in the arsenal of a photographer.
The question was whether to go for image quality at the expense of expressiveness, or vice versa. Even in the very moment when face to face with the object, the seasoned photographer needed to find a balance between quality and expression.

Reduces factors contributing to lower resolution across almost the entire aperture range, improving the sharpness of images taken at any aperture

Shooting practice with Digital Lens Optimizer
Because the Digital Lens Optimizer can improve sharpness over the entire aperture range, neither aberrations at full open nor diffraction when stopped down need to be a great cause for concern. Shutter speed can be at will, regardless of aperture stop.
Measures such as using an ND filter for slow shutter speeds or increasing ISO speed for high shutter speeds will rarely be called for, resulting in enhanced flexibility and responsiveness. Aperture and shutter speed cease to be a worry, allowing one's shooting style to become more creative.
Looks almost too good to be true.
Surprised I hadn't heard of it, given I was a Canon used from back the original EOS cameras in film days.
Looks almost like the sort of thing they would post on April 1st.
 

Tks

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#38
It is the computer programmes.
The "standard" designs which had been shown to have known strengths and weaknesses were then calculated for focal length using log tables.
Once computer ray tracing was fast enough any element layout could be investigated without it being almost a life's work so now we do indeed have some fantastic lenses which are complex.
It has always been the case that prime lenses have much better boke than zooms as well as having less distortion, flare and a flatter field. Zooms are getting better but I have a big psychological problem using a zoom for anything other than snapshots of grandchildren wizzing about!
Zooms have no inherent detriments quality-wise compared to primes (in reality, zooms are far more R&D heavy on development costs by quite a bit). Primes simply can achieve lower f-stops in the same package size, and cost less than an equivalent performing zoom, and naturally slightly less loss on clarity in the corners compared to zoom's extreme ranges of the focal lengths. See for yourself what end-game zoom lens can really do when money is basically no object.

Likewise the Zooms coming from the new mirrorless generation of releases are simply brilliant. Sony's 12mm-24mm F2.8 G-Master ($3,000 Made In China believe it or not) mops the floor with anything around those specs even in prime land. Again, if you got the cash, and the on paper aperture and focal length are to your flavor, and don't mind the generally larger sizes, newly released zooms for the mirrorless mounts can be purchased without reservation to quality. Their resolving power even at 50MP+ resolutions aren't impacted. Any hints of appreciable distortion are now corrected in-post.

That's not to say there isn't much progress in Prime land. Sony just delayed their 35mm f1.4 G-Master, but not before sending out a few pre-production units to Youtubers. That lens literally, seems actually (like literally from a performance perspective compared to any other 35mm within the same bracket) flawless for a photographer. The only single downside I see anywhere is perhaps if you're into video, there is noticable focus breathing.

Which also brings up an interest fact. By the nature of focus mechanisms, prime lenses can be technically considered zoom lenses really.
 
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