Why are modern lenses bigger than their older counterparts?

[rajatbhardwaj]

Hello,

I'm not sure if this is the right place to ask, but I'll start here.

Why is it that older lenses for systems like Leica, Contax G, etc. are smaller than something like the Sony FE mount lenses.

From what I can see, they both cover a full frame. I thought maybe the AF mechanism might take up a lot of space, but Leica MF lenses/Zeiss Otus lenses aren't the same size, and neither are the Contax G series/Zeiss Batis lenses.

I had heard something about film not needing the light rays to hit it perfectly straight like a digital sensor does, but then why can I use old smaller lenses on modern cameras?

What am I missing?

 

[Texas Parrothead]

I am really looking forward to the answer to this one as I have been thinking the same thing!!!!

 

[AksCT]

Size is strongly impacted by the brightness (max aperture opening) of the lens. It is simple physics of light. The other factors are related to number of internal elements, fixed vs zoom, glass materials, internal vs external focus movement and built-in stabilization.

 

[Promit]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Don't like vignetting? Image circle gets bigger and so does the lens.

Like IS? Now you need room for floating elements inside the lens.

Internal focus, or especially internal zoom? Now you've got a ton of extra stuff to squeeze in there. Don't want a rotating front element? Yet another piece to deal with.

It all starts to add up.

 

[rajatbhardwaj]

Size is strongly impacted by the brightness (max aperture opening) of the lens. It is simple physics of light. The other factors are related to number of internal elements, fixed vs zoom, glass materials, internal vs external focus movement and built-in stabilization.

This would make sense if the comparative lenses were the same size. Why is a Leica Summilux 50mm f/1.4 so much smaller than a Zeiss Otus 55mm f/1.4? They're both fixed focal lenses and have no in built stabilization.

 

[rajatbhardwaj]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Thanks for this! The above cleared things up for me, until I got to the last sentence. If digital does hate the steep angles, why is it perfectly fine to use the older smaller lenses on digital cameras? A Leica M9 (or a Sony A7RII with an adapter) seems to do just fine with lenses made back in the day.

Don't like vignetting? Image circle gets bigger and so does the lens.

This one definitely makes sense too.

Like IS? Now you need room for floating elements inside the lens.

The lenses I'm comparing, like the Leica Summilux 50mm f/1.4 vs the Zeiss Otus 55mm f/1.4 don't have IS in either one.

Internal focus, or especially internal zoom? Now you've got a ton of extra stuff to squeeze in there. Don't want a rotating front element? Yet another piece to deal with.

Same thing about the lenses I mentioned above.

It all starts to add up.

Definitely!

 

[pixelpushing]

Don't forget about focus float, we can't have any of that.

 

[ProfHankD]

Why is it that older lenses for systems like Leica, Contax G, etc. are smaller than something like the Sony FE mount lenses.

From what I can see, they both cover a full frame. I thought maybe the AF mechanism might take up a lot of space, but Leica MF lenses/Zeiss Otus lenses aren't the same size, and neither are the Contax G series/Zeiss Batis lenses.

I had heard something about film not needing the light rays to hit it perfectly straight like a digital sensor does, but then why can I use old smaller lenses on modern cameras?

Let's start with the last part. Yes, rear telecentric lens designs help with sensors, and they do tend to result in bigger (longer) lenses. There are also issues like sensor reflections, which make certain element shapes (e.g., flat rear surfaces) undesirable for digital cameras. There was also a lot of pressure to make rangefinder lenses small -- for example, too wide a lens diameter blocks the rangefinder's viewfinder.

As for the general question, it is not true that all modern lenses are bigger. When making the lens small is top priority, we can get tiny lenses -- for example, the APS-C Sony 16-50mm. For a full frame example, Cosina Voigtländer has been able to make lenses that are quite small, such as the 12.6mm-long (collapsed) VM 40 mm f/2.8 Heliar.

The catch is, especially for FE lenses, top priority has generally been something else. In many cases, something like maximizing MTF50 resolution has been the primary goal. Many of the newer lens designs are better corrected at the cost of being much more complex. For example, the old Minolta Rokkor PG 50mm f/1.4 consists of 5 groups with a total of 7 elements (that's what PG means), while the Sigma 50mm F1.4 DG HSM consists of 8 groups with 13 elements -- and is correspondingly bigger. Another example (specific to FE) would be the Sony 24-240mm: compared to the size of older 24-240mm lenses it... actually exists! Optical feats like that require complex optics, which tend not to be tiny unless you're willing to sacrifice some other attributes, and were literally infeasible years ago.

One more point: smaller sensors more easily allow smaller lenses. This is why superzooms all have tiny sensors. It also means that someone who really cares about size more than IQ has a multitude of choices that are much smaller than any viable FE lens would ever be. I'd bet that the reason Sony hasn't been giving lens size priority is that their market analysis said people who care about that are not the folks who buy A7 series bodies. Note that Sony makes plenty of other cameras for them.

 

[mike105105]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Thanks for this! The above cleared things up for me, until I got to the last sentence. If digital does hate the steep angles, why is it perfectly fine to use the older smaller lenses on digital cameras? A Leica M9 (or a Sony A7RII with an adapter) seems to do just fine with lenses made back in the day.

Don't like vignetting? Image circle gets bigger and so does the lens.

This one definitely makes sense too.

Like IS? Now you need room for floating elements inside the lens.

The lenses I'm comparing, like the Leica Summilux 50mm f/1.4 vs the Zeiss Otus 55mm f/1.4 don't have IS in either one.

Internal focus, or especially internal zoom? Now you've got a ton of extra stuff to squeeze in there. Don't want a rotating front element? Yet another piece to deal with.

Same thing about the lenses I mentioned above.

It all starts to add up.

Definitely!

The difference between those 2 lenses...modern design

Leica





Zeiss





Many more elements to correct different problems.



Mike

 

[Daniel Lauring]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Thanks for this! The above cleared things up for me, until I got to the last sentence. If digital does hate the steep angles, why is it perfectly fine to use the older smaller lenses on digital cameras? A Leica M9 (or a Sony A7RII with an adapter) seems to do just fine with lenses made back in the day.

Don't like vignetting? Image circle gets bigger and so does the lens.

This one definitely makes sense too.

Like IS? Now you need room for floating elements inside the lens.

The lenses I'm comparing, like the Leica Summilux 50mm f/1.4 vs the Zeiss Otus 55mm f/1.4 don't have IS in either one.

Internal focus, or especially internal zoom? Now you've got a ton of extra stuff to squeeze in there. Don't want a rotating front element? Yet another piece to deal with.

Same thing about the lenses I mentioned above.

It all starts to add up.

Definitely!

The difference between those 2 lenses...modern design

Leica



Zeiss



Many more elements to correct different problems.

Mike

Exactly. Modern glass materials, profiles and coatings can do things lens designers only dreamed about 20 years ago.

 

[Promit]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Thanks for this! The above cleared things up for me, until I got to the last sentence. If digital does hate the steep angles, why is it perfectly fine to use the older smaller lenses on digital cameras? A Leica M9 (or a Sony A7RII with an adapter) seems to do just fine with lenses made back in the day.

Steep rays are primarily associated with wide angle lenses and then mainly towards the edges. There are many people who have found many older lenses to be not "fine", particularly the rangefinger wide angles. There are many discussions about which adapted lenses actually work well on an A7R. But the newer sensors have continually improved their behavior with respect to angled rays in an attempt to deal with this, too (microlenses, shallower photon wells, etc). An A7RII is showing you multiple generations of improvements.

Keep in mind that the Otus is designed for a dramatically longer mount distance than the Summilux. This has implications for the lens design, since all of the rays need to be aimed nearly dead straight down the throat of the mount. The Zeiss can also focus closer than the Leica, and this seems dramatic when you consider that the distance is measured from the sensor plane.

There are also some other technical issues of note - both types of chromatic aberration, spherical aberrations, bokeh rendering, coma, distortion, ghosting/flaring, uniformity, field curvature, transmission, close focus distance etc. You should sit down and really try to compare two lenses of interest in terms of how they actually perform in all aspects, and try and identify the key differences. There are a lot of trade offs in lens design, and it's educational to identify which trade offs were made, when you can.

Modern improvements in glass, coatings, manufacturing, and computerized lens design have also made it possible to successfully use large numbers of correcting and tweaking elements in lens designs.

 

[No account anymore]

Size is strongly impacted by the brightness (max aperture opening) of the lens. It is simple physics of light. The other factors are related to number of internal elements, fixed vs zoom, glass materials, internal vs external focus movement and built-in stabilization.

This would make sense if the comparative lenses were the same size. Why is a Leica Summilux 50mm f/1.4 so much smaller than a Zeiss Otus 55mm f/1.4? They're both fixed focal lenses and have no in built stabilization.

Then start comparing sharpness and especially corner sharpness, the amount of vignetting, aberration like coma and astigmatism, etc., and things might start to explain themselves.

Also, take pictures of the night sky, and you will notice that the large, blue "blobs" around the stars are gone. This also affect daylight scenes. ;-)

 

[Keit ll]

All of these explanations contain some truth but when I see some lenses cut open I also see a lot of space surrounding a relatively small centre column of glass so why isn't the surrounding metal a bit smaller ?

 

[dbm305]

How, you ask?

Because decent pictures can now be got cheaply and easily.

So the market left for system cameras is for very critical people (and often on very critical 30+ megapixel sensors)

These people care about corner performance wide open; and looking at their images at 1:1 they can see the limitations of most lenses.

I don't know why most people care about corner performance wide open (yes I can see some circs in which you would, but for most wide open pics there'll just be bokeh)

But the market responds to what people what; and getting sharp corners wide open means bigger lenses. Yes your favourite f 1.4 Leica lens looks a bit dodgy in the extreme corners wide open an a high MP sensor at 1:1

 

[No account anymore]

All of these explanations contain some truth but when I see some lenses cut open I also see a lot of space surrounding a relatively small centre column of glass so why isn't the surrounding metal a bit smaller ?

Probably look and feel - design that sell, or design that is easier/cheaper to procuce, or maybe such lenses take more beating? Hard to tell.

 

[Keit ll]

All of these explanations contain some truth but when I see some lenses cut open I also see a lot of space surrounding a relatively small centre column of glass so why isn't the surrounding metal a bit smaller ?

Probably look and feel - design that sell, or design that is easier/cheaper to procuce, or maybe such lenses take more beating? Hard to tell.

I suspect that it is down to perceptions over appearance but many users keep asking for mirrorless cameras to be lighter & more compact & smaller/ thinner lenses contribute greatly to that aim.

 

[Adam-T]

Stablilizers and AF take up a lot of room - also Film is forgiving of a curvy image being presented to it whereas sensors need a flat projection , this means more complex optics

Also no one ever pixelpeeped those old film camera images at the equiv of 36Mp at 100% let alone expected the corners to be sharp wideoopen

--
** Please ignore the Typos, I'm the world's worst Typist **

 

[kryten61]

Size is strongly impacted by the brightness (max aperture opening) of the lens. It is simple physics of light. The other factors are related to number of internal elements, fixed vs zoom, glass materials, internal vs external focus movement and built-in stabilization.

This would make sense if the comparative lenses were the same size. Why is a Leica Summilux 50mm f/1.4 so much smaller than a Zeiss Otus 55mm f/1.4? They're both fixed focal lenses and have no in built stabilization.

Possibly one reason is:

Partly to do with the Retro focal lenses needed to allow a 35mm lens to be actually further away from the Film/sensor plane because of the DSLR mirror box. A 35mm lens in essence should have an optical centre that is 35mm from the film plane. bit had to do when the mirror box is already 2 to 3 centimetres so extra elements are used to allow this. So DSLR lenses are bulkier whereas the Summilux may have none or less as it was designed for a rangefinder camera.

 

[Lightshow]

It's a rich mix of many things.

The wide availability of digital testing suites (Imatest et al) means that every random jerk is now going in and charting how sharp lenses actually are, and in general we've got far more emphasis on the technical qualities of lenses. How much resolution could film ever resolve back in the day, especially with generic photo lab processing? Now we're looking at lenses designed to resolve 50+ MP and people want the lenses to do it across the frame. Combine that with the issue of digital's distaste for incident rays at steep angles, and the requirements of the design start getting pretty substantial.

Thanks for this! The above cleared things up for me, until I got to the last sentence. If digital does hate the steep angles, why is it perfectly fine to use the older smaller lenses on digital cameras? A Leica M9 (or a Sony A7RII with an adapter) seems to do just fine with lenses made back in the day.

It's not perfectly fine on the Leica M's, they introduced the 6 bit coding for in camera corrections.

Don't like vignetting? Image circle gets bigger and so does the lens.

This one definitely makes sense too.

Like IS? Now you need room for floating elements inside the lens.

The lenses I'm comparing, like the Leica Summilux 50mm f/1.4 vs the Zeiss Otus 55mm f/1.4 don't have IS in either one.

Lens design is all about balancing the tradoffs, distortion correction, aberrations, sharpness across the frame, resolution, etc... With size, complexity, and cost, the Otus was designed with few limits, so their size had to grow.

Then there are issues that must be dealt with, the Leica system was designed with the natural flange back distance of the lens in mind, the Otus has extra elements just so it can clear the mirror, if it was a 50mm lens, it would possibly require another element, and even more correction.

The Wiki camera lens design history will show you how advances in lens design, glass formulations, aspherical elements, and computer design, all contributed to the current state of the art lens design. https://en.m.wikipedia.org/wiki/History_of_photographic_lens_design

Internal focus, or especially internal zoom? Now you've got a ton of extra stuff to squeeze in there. Don't want a rotating front element? Yet another piece to deal with.

Same thing about the lenses I mentioned above.

It all starts to add up.

Definitely!

Trur, if the lens designer chooses to.

 

[Mike Fewster]

Size is strongly impacted by the brightness (max aperture opening) of the lens. It is simple physics of light. The other factors are related to number of internal elements, fixed vs zoom, glass materials, internal vs external focus movement and built-in stabilization.

This would make sense if the comparative lenses were the same size. Why is a Leica Summilux 50mm f/1.4 so much smaller than a Zeiss Otus 55mm f/1.4? They're both fixed focal lenses and have no in built stabilization.

All of the things like AF that others have mentioned. Plus Close focus distance. By and large, we expect out lenses to focus closer than used to be the case. Particularly true of the small lenses that were designed for RF cameras.