Have optic design changed in the digital age?

David Brown said:

Not to go off-topic, but, I held one of these Panasonics just this morning. It is larger than the 85mm "normal" lens on my RB67! The rep "explained" that it was because it was f1.4. I pulled out my Takumar 50mm f1.4 when I got home just to assure myself I wasn't crazy ...

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,,, and did you saw this:

HD Pentax-D FA* 50mm F1.4 SDM AW

• 
  
  
  • Focal length: 50mm
  • Aperture range: F1.4-16 (In 1/3EV stops)
  • Filter thread: 72mm
  • Close focus: 0.4m (1.3ft)
  • Maximum magnification: 0.18x
  • Diaphragm blades: 9
  • Hood: PH-RBB72 (provided)
  • Length / Diameter: approx. 80 x 106mm (3.1 x 4.2in)
  • Weight: approx. 910g (32.1oz)
  • Optical construction: 15 elements in 9 groups

vlasta said:

,,, and did you saw this:

HD Pentax-D FA* 50mm F1.4 SDM AW

• 
  
  
  • Focal length: 50mm
  • Aperture range: F1.4-16 (In 1/3EV stops)
  • Filter thread: 72mm
  • Close focus: 0.4m (1.3ft)
  • Maximum magnification: 0.18x
  • Diaphragm blades: 9
  • Hood: PH-RBB72 (provided)
  • Length / Diameter: approx. 80 x 106mm (3.1 x 4.2in)
  • Weight: approx. 910g (32.1oz)
  • Optical construction: 15 elements in 9 groups

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......an AF lens? What I did not feel fine with the parameters is the last stated characteristic :
15 lens elements? Why has this lens 50mm the need of 15 elements???
That sounds to me like "corection of failures with correcting element and from that failures a next
correcting lens element a.s.o. but marketing today is suggesting :

The more lens elements the better - like horse power ?

with regards

wiltw said:

In the early days of digital, with APS-C sensors, it was noted in the media that super wide angle FL had a problem with the different wavelengths of light being spread at different angles, and this cause the individual color-specific sensels to see light a bit more 'misaligned' (my term) and causing color fringing. So WA lenses for digital were designed so that the light rays struck the sensor surface a bit closer to perpendicular to the surface in an effort to reduce color finging with extremely short FL lenses.

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like a lens construction I mentioned :

a so called "telecentric lens design" ....but I have my doubts with the theory from
failures analysis by digital manufacturers = lens is responcible!
From my theory ALL FIRST DIGITAL SENSORS worked insufficiently!
So the problem should be solved meanwhile (with latest technology sensors) ?
No - from my point! Because latest and best technology sensors are working insuffficiantly
on a very high level! So has lens design changed? Perhaps - but then for compensating failures
of digital construction (no need with films....)!

with regards

faberryman said:

I get the impression that the only problem is with certain wide angle Leica M-mount lenses. I have not heard of any other manufacturer's wide angle lenses being a problem. If you want to use Leica wide angle M-mount lenses, you best bet is to use a Leica M-mount digital camera.

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The canon, leica screw mount, some of the voigtlander and contax wide angles all share this problem. And even on a M-mount digital, some of them still don't work well on digital but are wonderful on film.

trendland said:

......an AF lens? What I did not feel fine with the parameters is the last stated characteristic :
15 lens elements? Why has this lens 50mm the need of 15 elements???
That sounds to me like "corection of failures with correcting element and from that failures a next
correcting lens element a.s.o. but marketing today is suggesting :

The more lens elements the better - like horse power ?

with regards

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No

Sirius Glass said:

No

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+ 1 (in cases of doubts = fewer lens elements the better)
Prove : Zeiss Tessar 1902! Zeiss Sonnar 1931! Zeiss Planar 1896, 1926, Zeiss Biogon 1936, 1951!

with regards

trendland said:

+ 1 (in cases of doubts = fewer lens elements the better)
Prove : Zeiss Tessar 1902! Zeiss Sonnar 1931! Zeiss Planar 1896, 1926, Zeiss Biogon 1936, 1951!

with regards

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You entirely missed the point: more lens does not guarantee better performance. There are trade offs.

I don't actually know the answer to the original question, but I have a thought that may be relevant and worth discussion. A lens designed for film must be corrected for as many defects as possible because there is no correction in post for film. Some digital cameras allow for the correction (or at least partial correction) for some lens defects using software. This could allow the lens designer a little more freedom if he/she knows the lens will only be used on certain digital cameras. He/she could allow some deviation from best compromise for film if he/she is allowed to loosen up the target specification for aberrations that can be corrected in post. I think that lateral chromatic aberration might be an example if it is not allowed to be too bad. Certainly distortion would be an example.

I couldn't see it mentioned anywhere, but anyone interested in (*some of*) the (*potential*) differences between 'film-era' lenses and 'digital era' lenses might consider reading the following few articles:

https://wordpress.lensrentals.com/b...in-the-path-sensor-stacks-and-adapted-lenses/
https://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter/

Yes, there *can be* problems observed when putting film-era lenses on digital cameras (yes, I know this is the opposite of what the OP was asking, but trust me, I'm getting to it).
Especially wider-angles lenses, especially on short flange-distances mounts (mirrorless), but even more especially on micro 4/3rds.
In short, different sensors have different thicknesses of glass in front of them (for whatever reason), that bend the light again, *after* it has left the lens, and shows up as weird colour-fringing in the corners (when using lenses not designed for it).

The tl;dr of it is this:
The thickness of glass in front of a digital sensor is acting like a 'second rear element', changing the optical formula of *every* lens that's put in front of it. The thinner the glass, the more 'film-like' they perform.
That's no problem for digital cameras, *if you redesign the lens to account for this glass*, and that's what they do (see below), and that's what the OP is really asking: "do these new designs that take the sensor glass into account as another rear-element perform worse on film that lenses that were designed for film in the first place?"


Well, yes and no.

Certainly wider-angle lenses that are designed for the hugely thick glass on micro 4/3rds will have a hard time on film (but given that there are no film cameras that can fit these, they only cover a half-frame at best, trying to even adapt one of these to a film-frankencamera is insanity, so that's just a non-issue).

Voigtlander LTM/M lenses? I'm pretty sure they were all 'designed for film' as Mr Kobayashi is a big film fan, and they never made a digital camera (why design your lenses for someone else's digital camera?). You just need to look at all the posts complaining about trying to use these lenses on digital to realise that they were 'made for film'.

Leica Lenses? Probably not, they designed their digital cameras to mimic their huge back catalogue of film lenses, hence they have the thinnest sensor glass of anything in Roger's tables. So even their newest lenses now have to match not only their digital cameras but their legions of fans with old Leica film bodies (full credit to Leica lens engineers for managing to pull this off).

Back to the OP, Nikon (or even Canon) DSLR-era lenses? Well, their digital bodies look to have some *fairly thin* glass all round. More importantly, their *top* bodies (D1/1D etc) have the *thinnest* sensor glass. That says (to me) that they are trying to make their *best cameras* look better with *the widest range* of lenses, film lenses included. So why would they then go and redesign *new* (digital-era) lenses that look *worse* on their *best* new digital bodies? Doesn't make sense to me.
(Certainly they have more freedom with their 'digital-only' lines (EF-s, DX-format), if you could use them on a film camera I'm sure they would perform worse.)

Maybe for their Full-frame (real 35mm size) lenses they take a tiny bit of the effect of sensor-glass into account? Probably, they'd be stupid not to. But every engineering design is a compromise of objectives, and we can never know exactly what they're targetting without asking them.

But can you tell the difference anyway?
Especially when using a 'long' lens like 85mm?
Are you shooting Kodachrome 25 with a tripod set in concrete and enlarging to 4'x6' with a Super-Apo-Rodagon-HM-XL ? Yeah, you might see a difference...


(Also, as Alan just pointed out, there are a lot of corrections you can do digitally, I've seen reviews of people comparing the 'lens corrections' on and off, and for some of the cheaper bodies the 'lens correction off' photos are just absolute shite. But then the 'lens correction on' photos are also not as good as they could be, more post-processing just increases noise and/or decreases resolution, there's no substitute for good lens-design no matter what camera you're designing for).

Balancing all of this, of course, is lets just ignore the sensor-glass for a while and think about how much Computer Aided Design and fancy-glass manufacturing techniques have increased the quality of *top* designs in the last 20 years. Also balance that against the 'race to the bottom' to make cheaper and cheaper lenses. As always, you get what you pay for. No question a top-of-the-line lens that's 50 years old (I'm looking at you, Takumar and Summicrons) would easily outperform a cheapo-plastic lens designed yesterday, just as much as a new Otus would beat the pants off a POS from 50 years ago, no matter how you're capturing the image.

Sirius Glass said:

You entirely missed the point: more lens does not guarantee better performance. There are trade offs.

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Yes of course I know - my point is the following : I know a lot of people (beginning ~ in the 90s)
who state their new lens has a couple of more elements ! They are proud of most elements within their AF Nikons! That is like more horsepower! And that is of course nonsense!
The prove is from excelent lens design ~ 100 years ago! With a few lens elements!
Of course the argumentation : the less elements the better isn't correct also!
Today a new lens with less elements is often a cheaper one! Exeption some Leica from traditional
design and some Zeiss!
Why a standard lens 50mm with 15 elements? That is finally my point?
The reason is indeed : The task of additional elements is today a correction of other elements!
That is most in concern of special glass sorts of modern type!
In short : Your design is imperfect! But today it is no problem because a couple of additional
elements from correcting elements can make the basic design "nearly perfect"!
Beside the fact that additional correcting elements will cause the need of further correction!
So at last (the best example here) Pentax proudly presenting a 50mm standard lens 1.4
with 15elements - and amatheuric photographers can also be proud about in that way :
"My old lens had just 9 elements - the new one is providing me 15!!!"
BTW : Why Leica denied Zoom design for Leica optics such a long time?
(Their first "triplet" M-lens was a change - but no real zoom)!
Because Leica did not want to make compromises in regard of characteristics!
There is allways a smaler compromise with Tele Zooms AND Wide Angel Zooms!
But Tamron decided to 24mm-300mm - why?
Because of horse power!

with regards

PS : Next issue from lens design today is with AF lenses! Some manufacturers decided in the past
on one plastic element within that lens group of focussing! Because of its weight!
(interia)!
Well and plastic of course can have phantastic optical characteristics - Holga shooters will know!

Good english?

with regards

PS : WITHOUT TRANSLATER! (But from more short sentences)!

alanrockwood said:

I don't actually know the answer to the original question, but I have a thought that may be relevant and worth discussion. A lens designed for film must be corrected for as many defects as possible because there is no correction in post for film. Some digital cameras allow for the correction (or at least partial correction) for some lens defects using software. This could allow the lens designer a little more freedom if he/she knows the lens will only be used on certain digital cameras. He/she could allow some deviation from best compromise for film if he/she is allowed to loosen up the target specification for aberrations that can be corrected in post. I think that lateral chromatic aberration might be an example if it is not allowed to be too bad. Certainly distortion would be an example.

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Or are we allowed to state : The imperfection of tranfer to digital sensors is inherent in the system
of digital photography! And that will cause a much more expenditore in design!
Thats's my point Alan = with the same money you would get the better design for a film optic
= digital optics have to be worse if we regard the same price class!
(Software correction is compensating this disadvantage of digital)
So my conclusion = digital designed optics are not better ! Film optics are not worse!

Indeed it is the oposite!

with regards

PS : Wide agle lenses of type Voigtländer 12mm/15mm have indeed such a great sum of distortion, vignation, that a digital sensor will quit this with quality breakdown!
Zeiss lenses of M-mouunt type are a bit better! (double priced)!
The issue that even Leica M mount wide angle lenses will not work with digital is a serious prove
to me to state : There is indeed a disadvantage inherent in digital system!

Why it is not in hybrid forum?
From my practical experience on using lenses for both at both, I see no simple answer.
Some lenses from film only time are garbage on digital. Many are not.
Most if not all made after digital take over are just fine if not perfect on film.
Even some film only era lenses are fine on color film, but very boring on bw film, prints

Ko.Fe. said:

Why it is not in hybrid forum?
From my practical experience on using lenses for both at both, I see no simple answer.
Some lenses from film only time are garbage on digital. Many are not.
Most if not all made after digital take over are just fine if not perfect on film.
Even some film only era lenses are fine on color film, but very boring on bw film, prints

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Hi Ko.Fe.

Wich film only era lens is fine on color film but boring on bw film BTW?
Is it not often more in opposite direction? = old lens quite good for bw film but boring on color
film because of imperfect design and less correction for color?
What seams to be true for many pre war lens design? = phantastic results with bw film but not
designed for modern higher resoluted color films?

with regards

It is in the analog performance because the OP wants to know about digital lenses on analog cameras.

Trendland, since you have started using simpler and less complex sentences, your posts are much clearer. Thank you.

Sirius Glass said:

It is in the analog performance because the OP wants to know about digital lenses on analog cameras.

Trendland, since you have started using simpler and less complex sentences, your posts are much clearer. Thank you.

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You don't want to hear sentences of complexity in my native language - be sure about !

with regards

trendland said:

You don't want to hear sentences of complexity in my native language - be sure about !

with regards

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It is more about the thought being clearly understood as it is meant to be.

Trendland thanks as well. It is easier to understand your thoughts, which was the intent of my request.

Back to the topic: A lens whose marginal ray angle is perpendicular to the sensor is called a telecentric lens. This type of design is important in astrometry (for example) and machine vision where the position of objects in the scene do not move when racking through focus.

The drawback, however, is the lens must be roughly the size of the sensor. Not as big an issue with modern sensors so I’m sure most dedicated lenses are or nearly are telecentric.