What makes SL Lenses so big?

[Einst_Stein]

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Is it because of AF? Or simply Panasonic/Sigma are incapable of making small lens?

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[PhotoCruiser]

SL lenses can have different size, the Panasonic 100mm macro i saw was smaller than my Sigma 105mm Macro and afaik there are other Panasonic lenses being smaller than other brands.
AF definitively makes the lens bigger and heavier, low f stops as well.
My Nikkor ED lenses are a bit smaller than my Sigmas, but my Sigmas are 1.4 and 1.8 not 2.8as the Nikkors.
The only really smaller lens is the first series Nikkor 105mm 2.8 Macro, much smaller than my Sigma 105mm Macro.
Chris

[Stuart Richardson]

Lens design often boils down to three characteristics: Image Quality, Size and Price. You can choose 2. You could also put lens speed in there and choose 2 and a half or 3. In the case of SL lenses Leica chose to make lenses with the best image quality they could, and so the lenses are big. The price is high because all of Leica prices are high. But for Panasonic and Sigma, the lenses are cheaper and smaller, but not quite as good. But Sigma in particular has pulled out some magical lenses that have succeeded on all three, like the 24mm 3.5. 

In general lenses have gotten a lot bigger over the years because the demands of high resolution digital bodies are so much higher than they were for 35mm film. You might get 16mp of detail out of 35mm, but it will be softish. Now we expect 60mp to be sharp edge to edge with very high contrast. That means more complicated optical designs. As the lenses get bigger, the AF struggles to move all the elements in a traditional design, so then you also have to design the lens design itself to have internally moving elements that adjust focus and are light enough to be moved very rapidly. All these constraints influence the cost and size ratio. 

[Jeff S]

Some of the SL APO lenses, according to Peter Karbe, are bigger than would have been necessary for superb IQ in order to standardize the barrel size (and share some internal parts) to create economies of scale and make production more efficient and reliable. In particular, he said that the 35 APO could have been smaller than its longer FL counterparts, as would have been typical with lens design.  This extra space also created opportunities for him to optimize IQ, which maybe helps explain why he considered it his favorite SL APO at the time.

[Einst_Stein]

Are you saying SL is bigger than.M because of better optical performance?

[Jeff S]

30 minutes ago, Einst_Stein said:

Are you saying SL is bigger than.M because of better optical performance?

Are you asking me? I discussed why standardizing SL lens barrels made the 35 SL APO bigger than it needed to be. And, yes, more space gives a designer more ease and opportunity to enhance IQ. SL lenses are easier, and less costly, to optimize IQ without size constraints like M lenses. But of course there are other factors leading to SL lens size, including AF and stabilization mechanisms, etc.

[Einst_Stein]

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37 minutes ago, Jeff S said:

Are you asking me? I discussed why standardizing SL lens barrels made the 35 SL APO bigger than it needed to be. And, yes, more space gives a designer more ease and opportunity to enhance IQ. SL lenses are easier, and less costly, to optimize IQ without size constraints like M lenses. But of course there are other factors leading to SL lens size, including AF and stabilization mechanisms, etc.

You do mean SL lens can have better image quality than M, but do not feel comfortable to say it explicitly?

[Jeff S]

37 minutes ago, Einst_Stein said:

You do mean SL lens can have better image quality than M, but do not feel comfortable to say it explicitly?

Too funny.  Karbe has explained it in detail.  You don’t need my thoughts.

 

[LD_50]

This thread seems like it can’t possibly be a real attempt to learn about lens design. 

[frame-it]

10 hours ago, Einst_Stein said:

Is it because of AF?

probably not, have you used the Zeiss Otus 85mm? monster size and weight, and very high quality but its manual focus.

[jaapv]

8 hours ago, Einst_Stein said:

Are you saying SL is bigger than.M because of better optical performance?

No - it is bigger because it is another type of camera. Not being rangefinder it allows bigger lenses which gives the lens designer more freedom to attain better lenses. So it is the other way around. They are better because they are bigger.

[jaapv]

 

 

Actually the Summarit series of 2007 was the first time that Leica standardized  the mechanical parts of a lens series. They were exceedingly proud of the new production line, which was designed for them by Porsche Consulting. It allowed them to bring the price down whilst maintaining quality. Unfortunately the lenses did not sell as well as they should have, as the customers (unjustly) linked the lower price to a lower level entry product. We see the same customer response to for instance the SL Summicron lenses and SL zooms, forgetting that Leica only sources designs that meet their quality standards and more importantly, that Leica has been using designs  and products by other lens makers since the middle of the last century. 

 

15 hours ago, Jeff S said:

Some of the SL APO lenses, according to Peter Karbe, are bigger than would have been necessary for superb IQ in order to standardize the barrel size (and share some internal parts) to create economies of scale and make production more efficient and reliable. In particular, he said that the 35 APO could have been smaller than its longer FL counterparts, as would have been typical with lens design.  This extra space also created opportunities for him to optimize IQ, which maybe helps explain why he considered it his favorite SL APO at the time.

 

[Jeff S]

4 hours ago, jaapv said:

Actually the Summarit series of 2007 was the first time that Leica standardized  the mechanical parts of a lens series.

I’m aware, and similar to the SL APOs, the 35 was generally considered the star  by many, including Erwin Puts, who wrote about the benefits compared to its Summicron counterpart, including flare control.

[Einst_Stein]

All responses so far are saying the SL lenses are bigger because that gives them better performance and cheaper price. AF is the main cause though it also contributes to my the size. All above comments implies SL lenses could be potentially either better in image quality or cheaper in price than M lenses. 
Leica SL lenses are not obviously cheaper then M,  but people are avoiding to say it explicitly the SL lenses are better in image quality. It’s funny, but it’s OK, I get it!

[Jeff S]

55 minutes ago, Einst_Stein said:

All responses so far are saying the SL lenses are bigger because that gives them better performance and cheaper price. 

No, as Jaap explicitly wrote, they are better (in part) because they are bigger. The SL APO lenses are generally better optically than M lenses, in some key respects.  Watch the 2 hours of video if you want to more fully “get it.”  Bigger isn’t always better, but Karbe had specific goals, and excelled at achieving them.  The extra space greatly helped.  And the standard barrel size and parts sharing helped facilitate reliable production (as important as design) and cost efficiencies.

[jaapv]

I’ll happily say so. 😇

[Jeff S]

Karbe has repeatedly said that the SL35 APO is his best performing lens. Not coincidentally, it had even more free space than its SL APO counterparts, as discussed above.

[Einst_Stein]

25 minutes ago, Jeff S said:

No, as Jaap explicitly wrote, they are better (in part) because they are bigger. The SL APO lenses are generally better optically than M lenses, in some key respects.  Watch the 2 hours of video if you want to more fully “get it.”  Bigger isn’t always better, but Karbe had specific goals, and excelled at achieving them.  The extra space greatly helped.  And the standard barrel size and parts sharing helped facilitate reliable production (as important as design) and cost efficiencies.

I think we all get your points!

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[Einst_Stein]

12 hours ago, LD_50 said:

This thread seems like it can’t possibly be a real attempt to learn about lens design. 

You want to learn real lens design from a spontaneous web discussion like this? Be wise!

The goal of the question is to probe how people think or expect if SL lens can be as compact as M. Apparently, the responses think, to be so, the SL lens will have to lower the image quality (in some way?) or to be more expensive then M lenses! Also, it seems none think AF is the main issue, or  an issue at all.

 

[Jeff S]

34 minutes ago, Einst_Stein said:

I think we all get your points!

All except you, apparently, or this thread would have ended after a few responses. Btw, even post #2 mentioned that AF is clearly a contributing factor in SL lens size, repeated later by others, including me (post #6). Typical with your discussions, it seems; not quite troll-worthy.

Edited 9 hours ago by Jeff S