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Sigma : FE mount too small for ART quality lenses

Annna T

Active member
Sigma, recently interviewed by Mr Sama of the Spanish "DSLR Magazine", say they are receiving many requests for the development of FE mount lenses. But they consider the E mount diameter too small to produce excellent FF lenses like those of the ART series.


DSLR Magazine: hoy por hoy, el sistema configurado por las Sony A7, A7R y A7S parece que está –todavía– falto de objetivos ad hoc para estar completo y quizá le falte un poco de coherencia entre objetivos AF y objetivos de enfoque manual.
Con la enorme experiencia de la que dispone Sigma a la hora de crear ópticas para monturas de distintos fabricantes, ¿sería posible una cierta colaboración entre Sigma y Sony para desarrollar futuras ópticas? (ríen cuando, en mi "spanglish" digo "they need lenses")

KY: cierto: muchas personas nos dicen que tendríamos que hacer objetivos para esas cámaras A7 de 24 x 36 mm, pero nos gustaría estudiarlo. Y ello debido a que –en nuestra opinión– también en este caso, como en el de Nikon, la montura se nos antoja de un diámetro un poco escaso para el formato 24 x 36 mm. Sabes, Sony es capaz de hacer lentes de una calidad decente. En Sigma deseamos hacer objetivos de la más alta calidad y ese diámetro...

You can read the rest this interview here at DSLR Magazine.

If you don't get Spanish, Google translator is your friend..
 

Annna T

Active member
A little further down (after both have lamented the small mount and short register of the FE design):

DSLR Magazine: en nuestra opinión es una pesadilla óptica volcar correctamente los rayos de luz en ese hueco tan estrecho...

KY: tiene que haber una forma de resolver el problema óptico, tenemos que estudiarlo...

PS : that Sony chose a too small body and too small mount for a FF camera was my fear since the beginning.. The 55mm F1.8 wiped it for normal focal length and my 90mm F2.8 Tamron Macro is also an extremely good performer. But the jury us still out concerning wide angle. I think that with this mount, one shouldn't target extreme characteristics like F1.2 or F1.4, but aim for small, light but sharp lenses, exactly what the Loxia are already offering.. So I can understand why Sigma is hesitant here (has to study the question).
 

tn1krr

New member
Truth to be told this sounds like bs and an excuse; I think they just do not see the market as big enough yet as they could not reuse the same optical design outside Sony yet like they could with their their APS-C mirrorless lenses as adapting FF coverage lenses to MFT would not make much sense.

I mean, Nikon F Mount diameter is 2 mm smaller the Sony E if I remember correctly. If we can easily adapt Otuses, Apo Sonnars, Distagon 15/2.8, Sigma 35 ART etc. the only question that remains is how small can you make a superb quality lens for this mount. UWA presents its own optical challenges due to short registration distance and Sony's thick sensor cover glass (Zeiss talked about these issues in Photokina in context of Loxia design), but even these are only issues in terms of size optimization. Have long enough exit pupil distance in the lens and these become pretty much nonissues even for UWA.
 
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Annna T

Active member
Truth to be told this sounds like bs and an excuse; I think they just do not see the market as big enough yet as they could not reuse the same optical design outside Sony yet like they could with their their APS-C mirrorless lenses as adapting FF coverage lenses to MFT would not make much sense.

I mean, Nikon F Mount diameter is 2 mm smaller the Sony E if I remember correctly. If we can easily adapt Otuses, Apo Sonnars, Distagon 15/2.8, Sigma 35 ART etc. the only question that remains is how small can you make a superb quality lens for this mount. UWA presents its own optical challenges due to short registration distance and Sony's thick sensor cover glass (Zeiss talked about these issues in Photokina in context of Loxia design), but even these are only issues in terms of size optimization. Have long enough exit pupil distance in the lens and these become pretty much nonissues even for UWA.
Yes, but Nikon has a much longer register. When you add the two (small diameter and short register), it makes things more difficult for the FE mount. Of course it is a question of potential market. They have to sell gear to exist.

The challenge of designing good lenses for the A7 remains. And it should be something that fits well with the small A7 bodies in matter of size and weight.
 

UHDR

New member
i think it's just the standard CEO talk. what makes FE difficult is that the flange distance is large different to the rest of the market, and those micro lens means that the rear lens needs to be redesign. Sigma is good at making one design and make small changes to adapt to other system, for sony, it's probably too much development cost. and yet people might consider getting canon/sony A version and use adaptor instead.
 

ptomsu

Workshop Member
I am pretty sure that what Sigma says is right. Sony have stressed physics in this case which is never a great idea. Making mount and flange distance too small just for the sake of more compactness has to fire back somehow.

Look at the mount of m43, which is half the sensor size compared to FF and is much less stressed WRT to diameter and flange distance and thus makes lens design much easier. Which reflects in all the great m43 lenses!
 

jfirneno

Member
Yes, but Nikon has a much longer register. When you add the two (small diameter and short register), it makes things more difficult for the FE mount. Of course it is a question of potential market. They have to sell gear to exist.

The challenge of designing good lenses for the A7 remains. And it should be something that fits well with the small A7 bodies in matter of size and weight.
If the FE cameras become successful monetarily, I think Sigma (and every other lens maker) will be interested in making lenses for it. The fact that the registration distance is short does not mean you can't add space in the lens to project a good image. Maybe Sigma is saying that their existing lens designs would need expensive modifications to be used on FE cameras and they don't currently see the profit in doing it. Either way, I think between Sony and Zeiss we'll soon have some good lens choices to choose from.

Regards,
John
 

Steve P.

New member
It seems Zeiss have managed to make top quality lenses for Sony FE mount, albeit manual focus. I don't hear too many complaints about the Sony 55mm f1.8 either, so clearly it CAN be done. Whether Sigma wants to do it or not is a different matter but I think the interviewee from Sigma is being a little disingenuous in suggesting the FE mount is the stumbling block to them producing 'Sigma Art' quality lenses. As others have suggested, I suspect market size is a primary concern here. Manufacturers come out with this kind of comment from time to time on all sorts of things, insisting that something can't be done, right up until someone does it. Wasn't it Leica that once said it wasn't possible to make a 'full frame' digital rangefinder? :)
 

tn1krr

New member
Yes, but Nikon has a much longer register. When you add the two (small diameter and short register), it makes things more difficult for the FE mount. Of course it is a question of potential market. They have to sell gear to exist.
The longer register means the extra "size" is already in the camera body thickness; With DSLR UWA lenses you also always have extra glass to make chief ray angle small enough to clear mirror box.

Short register at least gives the opportunity to optimize size of overall package. Loxia 35 seems to be a good example; very short exit pupil distance, small size and quite high performance. With DSLR registration distance those 20-30 extra mm are always there even if the lens designer does not want or need them.

The challenge of designing good lenses for the A7 remains. And it should be something that fits well with the small A7 bodies in matter of size and weight.
High quality and small size is always act of balancing these two. Put bigger mount diameter and specially longer flange distance and you are just setting bigger minimum size for overall package; IMO this is kind of opposite what you would want when designing compact system.

ptomsu said:
Look at the mount of m43, which is half the sensor size compared to FF and is much less stressed WRT to diameter and flange distance and thus makes lens design much easier. Which reflects in all the great m43 lenses!
Sensor size in m43 is actually 1/4 of FF (~225 square mm for m43 vs over ~860 for FF) and as m43 lenses have much smaller sensor area to cover designing and manufacturing quality lenses is much easier, but this is much more of the factor of sensor size than anything else.
 

Annna T

Active member
Short register at least gives the opportunity to optimize size of overall package. Loxia 35 seems to be a good example; very short exit pupil distance, small size and quite high performance. With DSLR registration distance those 20-30 extra mm are always there even if the lens designer does not want or need them.
Loxia 35mm ? Are there already reviews available ? I saw a few for the 50mm, but I'd be glad to read about the 35mm too, if you have a link. Especially because I think that the challenge will be for wide angle (which we haven't seen yet, although the very first reviews of the 16-35mm sounds rather encouraging)

High quality and small size is always act of balancing these two. Put bigger mount diameter and specially longer flange distance and you are just setting bigger minimum size for overall package; IMO this is kind of opposite what you would want when designing compact system.
Concerning the body size : between the small APSC Nex bodies which Sony decided to use for the FE system and the size of traditional DSLRs like the Nikon D800 or the Canon D5, there was easily room to design a body at the same time smaller, lighter, but better adapted to FF sensors, something about the size of film range finders.

Concerning the compromises to consent in the lenses design, I think that the Loxia philosophy is on the right track. There are more than two elements to balance in a lens : to size/weight and IQ, you have to add fastest aperture and cost. IQ results also of the balance between several components : sharpness, micro contrast, uniformity, bokey, CA, distortion, etc.. My ideal lens would combine sharpness till the corners, high micro contrast and low distortion in a small size and weight. For this, I'm ready to give up on fast apertures (F 2.8 is enough or even F4 for wide angles), to put up with some CA and to pay a little more. I'm impatient to see whether Zeiss will be able to produce a performing 21-24mm Loxia.

Also, when considering the zoom lenses offered in the system, they are more or less as big as their DSLR counterparts. The Sony G 70-200mm is bigger and heavier than my Canon 70-200 F4 by a notch (and a lesser performer). This doesn't make much sense given the small A7 bodies.

These bodies are made for small and light fixed focal lenses of good IQ. I hope that Zeiss/Sony will be able to overcome the challenge presented by that mount and offer them soon, especially at the wide end.
 

jfirneno

Member
I hope that Zeiss/Sony will be able to overcome the challenge presented by that mount and offer them soon, especially at the wide end.
I am also very impatient to get a Zeiss 18 or 21 or 24mm native mount for my A7S. In fact I hope the 16-35 zoom and a Loxia 21mm are both proven good and available soon because I would be happy to own both right now.

Regards,
John
 

Annna T

Active member
on 3D-kraft: :)

Zeiss Loxia 2/35 - Short Comparison Review


(from completely unuseable to now barely unuseable :D)
Oh I saw that review a while ago. But I don't think one can draw any conclusion from these pictures : the performance of the corners is rather mediocre, but it could be due to a) not enough DOF and/or b) wind in the tree leaves.

Hopefully, the lens will be better than those pictures show, although the FE version has improved compared to the M version. !
 

Ulfric Douglas

New member
I don't see how the second point (short flange distance) can be remotely true as a restriction : it is the distance from sensor to rear element which is crucial, and that's completely up to the designer of the lens ... in this case Sigma. That manager is spouting gobbledigook for some commercial reason.
 

tn1krr

New member
Concerning the body size : between the small APSC Nex bodies which Sony decided to use for the FE system and the size of traditional DSLRs like the Nikon D800 or the Canon D5, there was easily room to design a body at the same time smaller, lighter, but better adapted to FF sensors, something about the size of film range finders.
Maybe there was but slightly more flange distance and bigger mount diameter would have pretty much killed adapting A Mount lenses with fast AF using LA-EA2/4. If you look at LA-EA4 it is pretty much as thin as one can put an SLT focus system. Kill adaptability of existing lens lineup to give lens designers a bit easier time? Did not propably take a long meeting to decide which way to go.

Concerning the compromises to consent in the lenses design, I think that the Loxia philosophy is on the right track. There are more than two elements to balance in a lens : to size/weight and IQ, you have to add fastest aperture and cost. IQ results also of the balance between several components : sharpness, micro contrast, uniformity, bokey, CA, distortion, etc.. My ideal lens would combine sharpness till the corners, high micro contrast and low distortion in a small size and weight. For this, I'm ready to give up on fast apertures (F 2.8 is enough or even F4 for wide angles), to put up with some CA and to pay a little more. I'm impatient to see whether Zeiss will be able to produce a performing 21-24mm Loxia.
At least small distortion and corner sharpness clearly translate to size. I have big hopes for UWA Loxias too. At short focal lengths I can almost forgive Zeiss the lack of electronic aperture and something like 18 or 21 with say F/3.5 speed should be possible to make quite small and high quality.

Also, when considering the zoom lenses offered in the system, they are more or less as big as their DSLR counterparts. The Sony G 70-200mm is bigger and heavier than my Canon 70-200 F4 by a notch (and a lesser performer). This doesn't make much sense given the small A7 bodies.
I have not seen anything suggesting that Canon 70-200/4 is markedly better performer than its Sony counterpart. Sony has dual AF motors (sensor focus has different AF motor requirements) that may explain slightly bigger size. I have the FE 70-200/4 OSS and it is quite ok to use with A7R body. Personally I would not touch anything that is slower than constant F/4 on that zoom range; for a meaningfull shrinkage in size the lens would need to be dreadfully slow.

The 16-35 zoom on the other hand is smaller and about 20% lighter than its Canikon cousins as it does not need extra glass to clear the mirror box.

These bodies are made for small and light fixed focal lenses of good IQ. I hope that Zeiss/Sony will be able to overcome the challenge presented by that mount and offer them soon, especially at the wide end.
Small and light fixed focal length lenses are gonna be small, dreadfully slow and light when focal lengths increase. If Zeiss made Loxia Apo Sonnar 135/2 for FE Mount it would be pretty much of same size as the Canikon version. I'm currently looking into getting a 135 and I want it to be at least F/2. Yes, it is gonna be almost same size as the 70-200/4, but I'm not willing to trade size for speed or overall optical quality.
 
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iiiNelson

Well-known member
I think there's room in the FE system for both the people who want small/slow lenses and people who don't mind dealing with the extra size to have fast/more expensive glass. My issue with the f/4 zooms or even the 35/2.8 FE is you have to stop down at least 2/3 of a stop to get the noticeably better performance which means jacking up ISO or shooting off a tripod and hoping your subject doesn't move - neither which are my preferred methods. I much rather have a f/1.2-f/2 lens and shoot from wide open to f/2.5 if need be.

As for this interview I agree on some level that maybe developing FE lenses is difficult but I don't think it's impossible to do if you choose to. There are some great lenses like the 55/1.8 FE, the Voigtlander 21/1.8, the 35/1.2v2, Zeiss ZM50/2 and countless SLR lenses that work well on the A7 bodies so it's possible to make high quality fast lenses.

Suggesting that a system was made "exclusively" for small and light lens because the body is light is absurd to be honest. There's a place and purpose for that within the system (especially shooting street photography in daylight) but the system is very flexible. That's the reason it became my primary system over the Leica M9 that I loved - how flexible the system can be. One can still choose to save weight over FF DSLR or money over a Leica M body. If weight and lens size are the users biggest issue or concern then Micro 4/3 has an excellent lineup of small lenses. If you want a bit larger sensor then Fuji would be a great choice as well. There really aren't many bad cameras these days.
 

Annna T

Active member
At least small distortion and corner sharpness clearly translate to size. I have big hopes for UWA Loxias too. At short focal lengths I can almost forgive Zeiss the lack of electronic aperture and something like 18 or 21 with say F/3.5 speed should be possible to make quite small and high quality.
Before UWA, we would rather need WA. I think that with a slower max aperture WAs can be made smaller and lighter. My Zeiss Contax G lenses (21 & 28mm) show very low distortion while still being very light and small; they open up to F2.8, but they exhibit rather heavy purple fringing.


I have not seen anything suggesting that Canon 70-200/4 is markedly better performer than its Sony counterpart. Sony has dual AF motors (sensor focus has different AF motor requirements) that may explain slightly bigger size. I have the FE 70-200/4 OSS and it is quite ok to use with A7R body. Personally I would not touch anything that is slower than constant F/4 on that zoom range; for a meaningfull shrinkage in size the lens would need to be dreadfully slow.
I have both and the Canon is clearly the better of the two, inspite of the front element of the lens being quite smaller. May be it is my copies. Of course the Metabones adapter results in very slow AF.


The 16-35 zoom on the other hand is smaller and about 20% lighter than its Canikon cousins as it does not need extra glass to clear the mirror box.
The Sony FE 16-35mm F4 is 3.9 x 3” (98.5 x 78mm) long and diameter and weight 18.3 ounces (518g), while my Canon 16-35mm F2.8 I is 84 mm (3.29″)
X 103 mm (4.06″) and weight 600 g (1.32 lb), aka it is barely bigger and a full stop faster.. But it is a rather crappy lens and you are right that the recent and highly prized F4 version is bigger and heavier.

Small and light fixed focal length lenses are gonna be small, dreadfully slow and light when focal lengths increase. If Zeiss made Loxia Apo Sonnar 135/2 for FE Mount it would be pretty much of same size as the Canikon version. I'm currently looking into getting a 135 and I want it to be at least F/2. Yes, it is gonna be almost same size as the 70-200/4, but I'm not willing to trade size for speed or overall optical quality.
For me a 135mm F2 is already a fast lens. I'd be happy with F2.8 and for wide angle where motion blurr is less of a problem, them F4 is enough. I will trade size for speed, but not for optical quality. Especially when it comes to wide angle.
 

turtle

New member
I'm not at all convinced. The 55 f1.8 FE is 'outrageously good', the 35mm is 'damn good' and my 16-28 Tokina EF via metabones is remarkable. At 16mm.....

Maybe some future lenses will need a bit more 'distance' from the sensor, resulting in longer lenses and maybe they will not be as perfect as with a longer register, but I'm not worried about optical perfection all the time, in every way, in a tiny package. We still have MF... SLRs etc. The FE camera/lens combo is a compromise, but its a brilliant one IMO.

Sony had to keep existing APS-C customers on board. Here was their catch, but I think they have pulled it off. Leica said FF digital was not possible. The technology will come for better ultra WA performance in time and we're already at the point of being able to make far larger prints than most people will ever be able to hang in their homes, so we perspective....
 

turtle

New member
FWIW, my Sony 70-200 f4 OSS is every bit as good as my Canon 70-200 f4 L. Long lens perfomance isn't the issue....
 

philip_pj

New member
Not to put too fine a point on, but if you are fair-minded on the subject, you are much better off listening to (i) lens designers from Sony and Zeiss, they come first as the men who are staking their reputations on what they tell the chiefs and the press (can find you an interview from the early pre-FE days if needed, re FF lenses on E); then (ii) product managers, the guys who have to sell the concept and answer for any problems; then (iii) chiefs, many of whom are what you might call 'top level Teds' because they are focused more on overall strategy at best, many are simply bean counters or worse.

I'm afraid the CEO of a rival company comes even further down the 'ladder of knowledge' especially one of a firm that has just locked itself into a strategy totally dependent on the continued health of the enthusiast segment of the falling DSLR full frame market, with two early releases of its headlining ART range characterised by boat anchor weight levels, huge complexity and Otus level physical dimensions.

So forgive me for being more willing to assign credibility to Christophe Casanave (Loxia Product Manager), Hubert Nasse (who almost certainly would have been consulted before CZ's involvement and author of the paper outing massive beam angle issues of M and ZM lenses on NEX Sonys) and the people in Sony's team, including designer of the FE primes, Naoki Miyagawa.

Photokina 2014: Interview with Zeiss product manager Christophe Casenave: Loxia, Touit, MFT and more | MirrorLessons - The Best Mirrorless Camera Reviews

http://www.fotoskoda.cz/images-old/multi/popisobr/ZEISS/Distagon.pdf

On the Loxia test at 3DKraft - it is little more than a shot out the window, obviously. I really rate this guy, so let's wait a little. If you know how to read MTF, you will be assured that, like the Loxia Planar 50/2, the 35/2 Loxia is a signficant improvement on the ZM predecessor. Zeiss are not in the business of releasing lenses with decreased performance - ever.

diglloyd: Zeiss Loxia vs Zeiss ZM 35mm f/2 Biogon on Sony A7R

http://www.zeiss.com/content/dam/Ph...oadcenter/datasheets_zm/biogon2_35mm_zm_e.pdf
http://www.zeiss.com/content/dam/Ph...downloadcenter/datasheets_loxia/loxia_235.pdf

"We’ll add to the family in the future with wide-angles and short telephotos. The challenge with these mirrorless cameras is designing an ultra wide angle lens that does not exhibit vignetting, lens shading and the ‘smearing’ effect common when using adapted wide-angle M mount lenses.” - Zeiss

As an RX1 owner, I'll pass on the 'better than for Leica' Biogon. When the Sigma folks can come up with something like the hand-assembled RX1, they might be worth listening to. cheers.
 
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