Just because small body and lenses is an advantage, doesn't mean it has to be small the entire time. ;)
(Also, the sheer framerates that mirrorless cameras are achieving versus DSLRs in the same price range...)

A pancake lens is a natural for any crop-frame camera, especially the small ones. Keeping things small, some will even fit in a large pocket. And they are cheaper to make and cheaper to buy. But the manufacturers can't make much profit selling them.
Sony have been negligent in producing new small lenses designed for their APS-C bodies. The last announcement was, I believe, 3 years ago.

Isn't it more easy to have one adapter (i.e. MC-11) between the lens and camera for all ART lenses, instead of putting that same adapter into each and every of the ART lenses?

Well Sigma sells this adapter only for Canon, not Nikon... and the adapter performance isn't never so good...

Which is fine - I use the Canon version of their ART lenses. AF is OK but not great, you are right. So putting this reverse engineering technique into the lens directly would improve AF performance? Remains to be seen.... but I hope you are right. I love their lenses (except for weight and size).

They are making completely new designed lenses for the mirrorless format, not just building an adapter into current lenses...

That would be even better... But probably not all lenses would require a specific design for mirrorless cameras... Long lenses like a 85mm or 70-200mm would have "an adapter added into current lenses"... Maybe wide angle lenses would profit from a new design!

Nearly all of them will benefit from a new design that takes into account the Sony sensor stack, micro lens array and auto focusing systems; that's why they are making an entire new line of lenses.

Ok... interesting... Hopefully you´re right, I already ordered my A7R III :D

Here's a few:
http://lenshero.com/lenses/lens-for-sony-alpha-full-frame-by-Sigma

In Addition to optics optimised for the smaller flange distance mirrorless lenses also need different AF motors optimised for contrast or hybrid AF (as opposed to PDAF in DSLRs). So taking a DSLR lens and simply adapting it to a smaller flange distance won’t do.

Nevertheless, I really wonder if Sigma really designs it’s mirrorless lens optics specifically for mirrorless cameras or if they just use DSLR optics and adjust for the different flange distance as all their mirrorless lenses are significantly longer than their DSLR counterparts. Please compare this lens and the Sigma 30 1.4 DN lens to the Fuji counterparts and it is obvious IMHO that comparable lenses (designed for the same sensor size, same aperture) specialised for mirrorless cameras can be much more compact without sacrificing image quality.

You can tell they don't do that based on how close the rear element is to the camera on their mirrorless lenses.

Yes, but even DLSR lenses sometimes do not have the rear element so close to the mount... And several Sony mirrorless lenses seem to have an additional ring added to the lens, to adapt the distance to the sensor... It may so be difficult to know whether a lens was optically designed specifically for mirrorless... But for sure, AF motors and electronic should be specific...

@captura the listed lenses are for A-mount, not E-mount...

There is no price and no release date yet. I'm sure those samples will appear.

T3 yes you are correct. small MILC excels if you're out and about with with only a small lens or 2.. i have sony nex(only gets used with 30mm sigma) and canon M /M2 and a SL1/100D for just that .but for the price of 2 fast pro oly lenses at more than 2K you can get a FF 6D and some affordable FF lenses especially as there is a massive stock of secondhand Canikon glass ..and get better results...my 85F1.8 cost £166GBP my 100F2 under£200 all mint my FF equivalent to the sigma 16 is my 35mm F2IS i pay £260 which is a stop faster than the sigma 16mm F1.4(when on m43) BUT WAY smaller at 62mm long vs 92mm so 1/3 smaller ..but you don't have to take out the FF body

@davev8 one can get a remarkably light (and cheap) combo with the A6x00 bodies using lenses like the Sigma 30mm, 1.9 2.8 lenses as a walkabout pairing: far far lighter than any DSLR, and, dare I say it, far sharper. I also have a A7R with a 24-70 Sony/Zeiss and the whole together with the Sigma lenses and filters weighs less than my Nikon full Frame with a 70-200. Low weight = portability meaning I can go further and faster which at my advancing years is far more important than a catalog of cannon lenses...lastly the Sigma lenses are so much sharper and lighter than any full frame lens I have ever used that I sometimes need to soften images to reduce the visibility of dust and like.

Well, that was just a guess. It may not ne true.

But I still wonder why this contemporary lens is so big. If it would bear the ART moniker, it would make perfect sense. But it is a CONTEMPORARY lens.

It is called CONTEMPORARY because the name ART has been re-assigned for use with DSLR's.

@ Captura: I didn't know that. That's a strange move IMHO as it implies that only DSLRs users want top-notch optics.

Not really. It's just just a sub-brand name.

Come on, how can a 16/1.4 lens be small? -_-

It can't. But I suspect that most M43 owners would prefer a smaller 16mm f2 or f1.8 lens instead, from Sigma.

It definitely can. Please compare with the Fuji 16 1.4 which is about 2 cm shorter (but admittedly much more expensive).

Compact or not, this lens probably gives high value for one's money.

If only the 19mm F2.8 is 16mm
24mm vs 28.5mm is big difference for landscape

if i use a prime it has to be as least 24mm, wider say 21mm even better
remember one can crop to make 24mm become 28.5mm or 35mm but not in reverse

I can tell you that my 30/1.4 DN DF C lens is WAY better in all respects, compared to the Sigma 30/2.8 lens.

So good for but you better should compare in everything your lens with the equal Sigma 2.8/ 19... 🙄

"At first glance, the 18-105 seems "huge", but it actually feels surprisingly light and comfortable nesting on your left hand while shooting"

U hold this in one hand and feel surprisingly light?
if so u must be a strong man

@Jefftan - "U hold this in one hand and feel surprisingly light? if so u must be a strong man"

So basically you're telling us that you hold your cameras like a point-n-shoot? No thanks, I use proper camera holding technique. Sounds like you need a lesson:

http://media.digitalcameraworld.com/wp-content/uploads/sites/123/2014/06/How_to_hold_a_camera.jpg

Like I said, I've traveled extensively with the 18-105/4, which means I've carried it for hours on end, doing all-day shooting with it. Yes, it's surprisingly light. I used to travel with a Canon 60D, which weighs 755g. My A6000 (344g) with Sony 18-105 (427g) combined weighs only 771g-- only 16g heavier than the 60D body alone! So you don't need to be "a strong man" to hold the Sony combo with one hand, because it's only the weight of a 60D body. I also used to travel with a Canon 17-40/4L (500g) on the Canon. That lens was 73g heavier than the Sony 18-105/4 OSS.

To state the obvious the Samyang isn't a 24mm equivalent its 18 and that is a world of difference. The Samyang weighs 310 G with a 67mm diameter (I just weighed mine) and the Sigma 405 grams with 72 mm dia. Does 95 grams and 5 mm more really make it "huge"? Whether its sharper than the very decent Samyang remains to be seen but I am expecting it to be. Its a much more versatile lens that's for sure.

T3:
thanks for the picture.
But may I ask for the left hand supporting the lens, is that left hand under the camera body and supporting the camera body too?

"The Samyang weighs 310 G with a 67mm diameter (I just weighed mine)"

Why the big difference?
Samyang 12mm F2 specification said it is 245 gram, why u said 310 gram

for landscape 18mm equivalent maybe better than 24mm (can easily crop to 24mm from 18mm and not reverse)

It can be useful under some circumstances. I hiked up Mt. Fuji this August. Most of the hike is at night without artificial lighting--lamps of the hikers excluded. You also don't exactly have the time to set up a tripod, since the group will be pushing you on at all times except when you're desperately trying to rest your feet. I used the 28mm Sigma and cranked up the ISO to 12k. I had the stabilized 1.8 Sony with me too, but being 35mm it was just to long.

Granted, none of those pictures are going to win any competitions or are even remotely good, but it was either that or no pictures of the hike up at all, so I am quite happy to have had that lens with me. Given an opportunity, I would have prefered a wider, faster lens. It's a special case, but those definitely exist.

The one issue I see with this Sigma is that--like my current Sigmas--it is not stabilized, which is kind of a big deal at night.

Thanks for the explanation.

So that means this lens isn't called an Art lens because it requires digital processing to correct for optical aberrations. I suppose that means it "really isn't as good as an Art lens."

So isnt optically as good as an Art series lens but gigantic size anyway. Sounds like a product cynically shoved out to separate mirrorless users from their money, using the word "Sigma".

Good enough for E mount, monstrosity for m43. :o

In all seriousness, I love Sigma for their FF DSLR lenses, but all their mirrorless lenses so far are competent yet unexciting. :/

MFT make 120mm F2.8 make the most sense to me

Jeff.... yes it would make sense. If you recall, a few years ago Panasonic had planned a 150mm f/2.8 lens, but it somehow got dropped from their lens roadmap.

And a long macro lens might even be better. Something like a 100mm f/2.8 macro.

If there is a "gap" in the M4/3 prime lens lineup, then it isn't anywhere under 50mm. It is between 75mm and 300mm.

@Marty,
32mm equivalent seems like a more useful FL than 24mm.

Well... Are the pancakes actually any good? I tried a Sony 20mm pancake once and it was like scuba diving.

16mm pancake definitely not good
but that's the price u paid for having a 24mm equivalent pancake

all depend on how u look at it
with it, it is compact camera size and retain APS-C color tone and dynamic range
but than lost the sharpness (expecially edge) of a good lens in RX1000V

worth it or not, u decide

@Fero,
Did you actually shoot the 30/1.4 on your A6000? The one I tried had awful nervous bokeh. This has been attributed to a Sony APS-C problem called 'Onion-Skin Bokeh' in the past.
The 30/1.4 only makes beautiful bokeh on M43 bodies, in my experience.

@captura
I've sold it a couple of months ago and now that you mention it there is some "onionness" on some of them. :(
I didn't care about it at the time. (As in: I haven't noticed.)
I still think it's still a good lens, though. At least the razor-sharp part remains.

I have to note that the onion rings are only apparent with mid- or low-level brightness brilliant light sources, they kinda disappear if these dots are clipped. I guess no surprises there.

Yes, but perhaps not so much a lens problem but a systemic problem Sony has with its's bodies and several other lenses as well. This has been well covered up it seems. But I am way out of my depth with this.
All I am saying is this may help to explain the superior bokeh with this lens on M43.

What about using a tracker and apertures that reduces vignetting and aberrations for astro - way more pleasant results.

exactly what I am thinking
If F1.4 not enough DOF for landscape that not much use to me

never use such a fast lens
I only know APS-C F2.8 still have enough DOF for landscape

I would not use it wide open for anything else than astro photography, but thats just me.

Sigma promise and may indeed be true
this lens has good IQ wide open

"I would not use it wide open for anything else than astro photography, but thats just me."

why? for lens IQ or DOF ?

@Jefftan:
"I would not use it wide open for anything else than astro photography, but thats just me."
for DOF reasons only. I believe that the quality of the lenses is very high and so I dont worry about IQ - that might be optimistic or self-limiting but thast what I do.

At ~24/~F2 this lens have a lot of DOF. For me enough even for landscapes. But this is more personal preference/situation.

btw. Don't focus at infinity for landscapes, you will loose a lot of DOF. (there is always more DOF behind focal plane than in front of it.)

"Don't focus at infinity for landscapes, you will loose a lot of DOF"

But that is how I get my Laowa 15mm F2 to work
I found hyperfocal distance useless, the whole image simply not sharp

for that lens I use at F4 and focus at something very far away (I guess that is infinity)
I got a sharp pictures and anything outside say 6 feet (just a guess) seem to be in foucs

anyway if F2 is enough DOF for 24mm APS-C, what about F1.4?

@mario loconte The Sony 16mm 21.8 pancake is I am afraid a sorry excuse for a lens. Its simply horrible. The Sigma DN lenses on the A6xxx bodies are an absolute revelation in sharpness, distortion and freedom from vignetting ( a particular issue for the Sony 16 mm)

I just weighed my Samy 16/2, it is 503g, SLR design (APS-C) so a bit big, especially with the built-in adapter for mirrorless. It's a lovely smooth lady though. I'm a sucker for large aperture wide things for shooting at mfd and this Sigma is a bit magnetic.

He was referring to the size of the lens. He's counting ounces, not pixels.

The previous 30/1.4 hangs pretty well with the PanaLeica 25/1.4 for half the price, albeit at a somewhat larger size (longer in particular). This one is actually a little larger than the upcoming Oly 17/1.2 but the difference is far smaller than in the case of the 30 vs PL25, course you're comparing f1.4 vs f1.2 at the point but still...

I'm betting if it's priced anywhere near $500 or less it'll sell well amongst M4/3 users, heck even at $800 it's still undercutting the Oly by $400 and M4/3 could use a premium 16-17 with AF. It's now getting two... The 17/1.8 & 20/1.7 are both great but both have some flaws that other primes in the system don't (quirky or useless AF for certain things, or curved focus plane and softness for the price, etc)

@Robin, actually it'll be a 32mm for me, and will be my first sigma since the 80's, but I like the way they do business. cheers

Think it'll be out by Christmas? That would actually tempt me to try/get it over the upcoming Oly 17, somehow I'm doubting it when they're still not talking price. I'm betting it'll be way cheaper than the Oly regardless.