[ElJamoquio]

....and thermal stability

Polymers expand/contract 5-10x more than metals. They're less stable.

As a fun aside, look at the gaps in the body panels of a Saturn car made before ~2002, if any are still on the road. You could stick your fingers in some of them.

[scratchpaddy]

Polymers expand/contract 5-10x more than metals. They're less stable.

That's why Sigma developed the "Thermally Stable Composite" (TSC) that has the same coefficient of expansion as aluminum.

And, Saturns were darn good cars before 2002. Cheap, but good. My Dad put over 350,000 miles on his '94 wagon, and yes, it is still on the road, plastic body and all.

Anyway, I'm looking forward to see how this lens performs. I'm sure it'll be excellent. What's next, a refresh of the 85 f/1.4, bigger than ever?

[canonguy]

Most quality 50's are so damn sharp already - this seems overkill to me (except maybe for full frame, 20mp cameras). ....but as they say, if you build it - they will come (w/$$$)


So for maybe $700.00 you can go to 97% of an optically perfect lens up from the 95% perfect lens you could get for $500.00 previously from Pentax or Sigma versions. All for differences you can only see under a microscope???

[pinholecam]

Another big lens (and 50mm lenses were usually small in the past).
Someone needs to get past the ego boosting that big lenses give, sit down and think about what they want from their lenses.

[Uluru]

Another big lens (and 50mm lenses were usually small in the past).
Someone needs to get past the ego boosting that big lenses give, sit down and think about what they want from their lenses.

My favourite and still well in use is manual SMC 50/f2— fantastic character to images and the lens is very small. Very light too.
I would love 50 mm f2.8 at half the size of this Art lens, more than half the weight and more modest filter thread diameter. But optically beautiful and maybe WR.
Art lenses from Sigma are definitely not for everyday use. I personally prefer a lens that allows me to take 10x more photos with ease than one great photo with exhaustion. No wonder beginners and tech geeks are amazed with these Art lenses from Sigma.

[scratchpaddy]

How about a refresh of the Sigma-Built Spiratone 135mm f/1.8 Y/S? That thing had the size (and weight) of a shot put.

Actually, a new 135 f/1.8 is supposedly on Sigma's to-do list, if rumors are to be believed. It will be enormous, for sure.

Re: your comment on build quality, have you handled any of the new Art lenses? They are extremely solid, much more so than their previous offerings. Sigma is also one of the few remaining companies who don't outsource production to Vietnam, China, the Philippines, etc.

[Winder]

I will definitely be watching for this lens. I'm looking at picking up a Fuji XE-2 and the 56mm F/1.2 if it reviews well. If the new Sigma 50mm is really good I might have to wait for a K-mount. My current Sigma 50mm F/1.4 is one of my most used lenses.

[tigrebleu]

While this lens uses a double gauss design, I doubt we can call it that... Rather, it's more like a double double gauss lens design, LoL.

It looks like if two double gauss design lenses were stacked one in front of another. I trust Sigma to use this design in order to improve image quality. I got the feeling this lens will beat the crap out of the other 50s (and/or 55, 58, etc.) out there...

Here's a random guess: razor sharp wide open, razor sharp at middle apertures and razor sharped stopped down until diffraction sets in, low CAs, low distortion, low light falloff, etc.

In fact, the only thing I don't like about the Sigma lenses is their flare resistance, which is... pretty bad. I owned the 70mm Macro, which was pretty good with flare resistance, but I did use the 10-20mm F/4-5.6 on my K-7 and 17-70mm F/2.8-4 "C" on my K-5 on a few occasions, and both were uber ugly for stage event photography, and were so because of the atrocious flare issues they were plagued with.

The 10-20 makes every spotlight turn into a supernova of distorted rainbow colors, and on the 17-70, a reflexion of every light source appears at the bottom of the image. Otherwise, they're respectively good and great lenses, and both are very, very affordable.

[azerak]

I have the Sigma 35mm 1.4 and if this new Sigma 50mm 1.4 is anything like the 35mm, then it is something that is wonderful. However, the ART lenses certainly are not for you to use as walkaround lenses due to the weight. For that, I use my DA 50mm 1.8 and Sigma 24mm 2.8 instead.

[tigrebleu]

Polymers expand/contract 5-10x more than metals. They're less stable.

Some newly designed polymers are much more thermal resistant and don't expand or contract much (though still not as little as metal). But they're rather expensive... My guess is Sigma used a bit of these in their lenses featuring "thermally stable components", where metal would be difficult or improper to use.

As a fun aside, look at the gaps in the body panels of a Saturn car made before ~2002, if any are still on the road. You could stick your fingers in some of them.

LoL! But then, the old Saturn cars don't have rust on any of these polymer panels.

Joke aside, no comparison between lenses and cars possible. Lenses usually don't stand outside in -5 to -20 Celcius degrees for all winter, nor do they stand under the degrading UV rays of the sun all year long.

But I get the point, polymers do expand more.

[jeffshaddix]

Interesting, and thanks for the optics analysis. We're also expecting an ultra fast Samyang 50mm this year - I'm looking forward to the seeing the results of both.

[Class A]

Most quality 50's are so damn sharp already

I don't agree when it comes to apertures near f/1.4.

For instance, the Pentax FA 50/1.4 is not that great near f/1.4 and many other fifties are similar.

Yeah, it has HSM, but I have to agree, this thing is enormous and kind of defeats the purpose of having a 50mm in the first place

What is the "purpose of having a 50mm"?

I believe the purpose of a lens should be to give the photographer a large range of options. Many lenses force you to stop down to get decent sharpness and/or bokeh and hence limit your options.

The new Pentax DA 20-40/2.8-4 is a case in point. It seems to be made for the benefit of photographers themselves with its small size, weight and beautiful build quality.

In contrast, lenses like the Zeiss Otus or the new Sigma Art lenses seem to be made for the viewer. Sure, the photographer will have to deal with a larger, heavier lens, but when it comes to the image viewing, only quality counts. The weight you had to carry around or the size you had to deal with will be irrelevant at this point.

If a lens can be kept compact and still deliver stellar IQ, great. But if it needs to be made large then so be it. I prefer that to a small beauty that limits your options.

[Apapukas]

I don't agree when it comes to apertures near f/1.4.

For instance, the Pentax FA 50/1.4 is not that great near f/1.4 and many other fifties are similar.



What is the "purpose of having a 50mm"?

I believe the purpose of a lens should be to give the photographer a large range of options. Many lenses force you to stop down to get decent sharpness and/or bokeh and hence limit your options.

The new Pentax DA 20-40/2.8-4 is a case in point. It seems to be made for the benefit of photographers themselves with its small size, weight and beautiful build quality.

In contrast, lenses like the Zeiss Otus or the new Sigma Art lenses seem to be made for the viewer. Sure, the photographer will have to deal with a larger, heavier lens, but when it comes to the image viewing, only quality counts. The weight you had to carry around or the size you had to deal with will be irrelevant at this point.

If a lens can be kept compact and still deliver stellar IQ, great. But if it needs to be made large then so be it. I prefer that to a small beauty that limits your options.

I like your thinking, but I would like to add that the image is the result of the shooting process. So everything that shooting process consists of, have an impact on the final result.

Sharpness, bokeh, CA control etc are specs that are very important in the shooting process, but the thing that is often forgotten is - the joy of photographing. I believe it is one of the most important (more important than sharpness) ingredients for making a tasty photo.
The thing why Ltd's are so loved are because it is a joy to use them. Of course, they are good optically, but that is not their strongest part. The first lenses I got after kit lens were DA Ltd's and at that time it was all about the joy of photography for me.
With the Sigma the situation is totally different. When I started to make some from photography, occasionally I found myself in the need of faster lens. So I got, Sigma 35mm. Results are fantastic, but what I also found is that photography became less about joy, more about getting the result (for the client). That is a big red flag.
I've seen wedding photographers that take photography as their job. No more. People who once were taking their cameras with them whenever they can because they enjoyed shooting, now only shoots when someone pays.
So, what I am trying to say, it is not only about sharpness, bokeh etc but how much excitement and joy you will feel using that particular lens

[Uluru]

.. But if it needs to be made large then so be it. I prefer that to a small beauty that limits your options.

As life itself, good art is never created out of abundance.

[Class A]

So, what I am trying to say, it is not only about sharpness, bokeh etc but how much excitement and joy you will feel using that particular lens

Absolutely.

Some lenses, e.g. the FA 43/1.9, inspire me to use them and get the best out of them. So I completely agree with your statement.

However, I don't agree that a Sigma 35mm cannot be such a lens. Maybe your feelings towards this lens are influenced by the (commercial) context you used it for.

The Rokinon (Samyang) 85/1.4, for instance, is a pretty big lens, however it has excellent image quality and nice manual focusing so it also is a lens that inspires me to use it, even though it is not a small, limited lens.