Geek Articles

MTF Tests for the Sigma BBL: The Big, Beautiful, 85mm Art Lens

Yes, I know the Sigma 85mm f/1.4 DG HSM Art lens just too big for you; reading the online forums, you’d think it was about the same size and weight and a 600mm f/4 lens. It’s not, of course, although it is a hefty lens at nearly 40 ounces. But that’s just a few ounces more than a Canon 85mm f/1.2 L; a few less than a Zeiss 85mm Otus. So while it wouldn’t be my first choice for a backpacking lens, it’s not as wrist-breakingly huge as some make it out to be. (OK, full disclosure, backpacking isn’t my area of expertise. The closest I get to camping is staying at a hotel without room service).

While you guys get the ‘It’s so big’ jokes out of the way, I’ll point out that making a lens bigger is not a goal of the lens designer, but it is sometimes a necessity. If you want to get great optics and eliminate aberrations, you either need lots of pieces of glass or very expensive pieces of glass ground into very expensive shapes. The Sigma 85mm Art has 14 elements, compared to 8 for the Canon 85mm f/1.2, and eleven for both the Zeiss 85mm Otus and Milvus lenses. If you want to keep the price lower and the image quality excellent, then more glass is sometimes the compromise you make.

Of course, that explanation assumes that yes, they did make the image quality excellent. Given what we’ve seen from the rest of the Sigma Art line, I certainly expected this one to be excellent. And our Photo Guys article on real-world use certainly seems to suggest Sigma did the right thing with this lens. But I don’t trust what I see in photographs, so let’s get the optical bench out and see if it’s really so. (That was a joke for all the people who say ‘I don’t trust what I see in MTF plots, I want to see photographs.’ A joke.)

MTF Results

This is the MTF results generated in our usual fashion: 10 copies were tested, each at four different rotations, and all the results averaged to give you the MTF shown below.

Olaf Optical Testing, 2017

 

That’s most impressive to me at a glance, but it’s probably easier for you to be impressed if you look at some comparisons. So I’ll make some comparisons between the Sigma Art’s MTFs and some other lenses below. For those of you who don’t speak MTF, it’s pretty simple. “0” Image Height is the center of the lens, “20” is almost to the corner. Higher MTF is better, and if the dotted and solid lines are close together for each color, that’s good too. There’s a lot more to MTF, but that will get you by.

Sigma 85mm f/1.4 Non-Art vs. Sigma 85mm f/1.4 Art

First, let’s compare the new Sigma Art (on the right) to the older Sigma 85mm f/1.4 lens (left). It’s no comparison.

Olaf Optical Testing, 2017

 

Sigma 85mm Art vs Zeiss 85mm f/1.4 ZE

The Zeiss 85mm f/1.4 ZE is close to the Sigma in price and makes a good comparison – unless you’re comparing autofocus capabilities, of course.

Olaf Optical Testing, 2017

 

This one I have to give the edge to the Sigma. That’s not surprising, the Zeiss is a decades old design, and while it’s razor sharp stopped down a bit, it’s a little soft and dreamy looking wide open. It’s a good example of a lens people love for its unique look, rather than its resolving ability.

Sigma 85mm Art vs. Zeiss 85mm Otus

Well, sooner or later we had to compare it against the best 85mm we know of, the Zeiss 85mm f/1.4 Otus. I chose sooner.

Olaf Optical Testing, 2016

The Sigma certainly holds it’s own. Of course, the Otus is sharper in the center, especially at higher frequencies. It’s sharper than about anything other than super telephotos in the center. Away from the center, the Sigma very much holds it’s own.

Variation

We’re still listening to outside consultants argue about the best way to present a variation number, so I’m going to stick with just using our variation graph. The Sigma shows excellent copy-to-copy variation control, as good or better than the Canon L, Nikon G, or Zeiss offerings in this focal length.

Olaf Optical Testing, 2016

 

Conclusions

This was an MTF test. It was only an MTF test. Had this been an actual lens review you would have been instructed to purchase the Sigma from my affiliate link to help send my kids to college. As MTF tests go, though, this is just another ho-hum spectacular triumph for the Sigma Art series. From an MTF standpoint, it’s better than any other 85 except the Otus, and it makes a very respectable showing against that fine lens.

There’s a lot more to imaging than MTF. Even I, the ultimate MTF geek, know that. What we found out today is the Sigma is a really, really sharp lens at an excellent price. That makes it worth further investigation if you are thinking about an 85mm lens. It doesn’t make it the right choice for you, lots of other factors need to be considered. But the Big Beautiful Lens is worth a long, hard look.

Addendum:

I was so impressed with the BBL that I thought I would run Field of Focus graphs on it to. Color me impressed (the graphs are colorful, get it?). It is perfectly flat from one side to the other. Superb.

Olaf Optical Testing, 2017

 

Roger Cicala and Aaron Closz

Lensrentals.com

February, 2016

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in Geek Articles
  • You mad bro?

  • Carl Eberhart

    Dude get over yourself, read the tests and weep…

  • Hysz

    True. It’s hard to imagine that every sector is targeted by marketing and photography isn’t. Of course there will be numerous ‘tricks’ to con person into buying this lens, vs some other lens. I like it how Sigma new Art line isn’t made like that, as far as ads go. It defends itself with great IQ, no need for golden/red rings to boost sales.

  • JerryC

    People just pay for the red or gold ring, not the lens itself most of the time.

  • JD

    WHAT ABout comparisons to the Nikon 1.4 AF-s as well as the older AF-D?

  • Nemo Niemann

    I have shot it with outer focus points at 1.4, though I rarely shoot any lens wide open. I calibrated the 85/1.4 I bought with Reikan FoCal. Great software to automatically adjust the micro focus. So, the lens was sharp when I used the outer focus points.

  • Buc Nelson

    yet another post about tamron, do you work for them? check his discus post history, unless he’s turned privacy off by now.

  • Martti O Suomivuori

    Could you now please drop it and take it apart, see how much Silicone Marmalade it has eaten to become so fat.
    Sigma has certainly come a long way.

  • Van Forsman

    @ptakeuchi:disqus part of the issue you’re foreseeing is that the lens mount on the camera could be bent by the lens torquing on it. If you look around online, you might find examples of it, but as roger said, it’s really an issue only with sudden acceleration, i.e. jerk.

  • Brandon Dube

    We don’t test APS-C or (generally) M4/3 because there are less lenses for those mounts than EF, F, etc. Fuji, etc, may require us to build a new electronic passthru for the MTF bench which is also a great investment of time. They’re also just less interesting to us.

  • Patrick Chase

    Sigh. Just as I was about to buy this lens Sigma went and announced a 135/1.8 (which is currently a bigger gap in my lineup).

    Let us know when you get a few of those to test, m’kay? 🙂

  • Your message needs more “…”, that alreay indicates you have some serious issues. Speaking of DxO – their problem is consistency, and compressing results into a single number used for meaningless rating system.
    42. Enjoy! 😉

  • sickheadache

    Oleg…Yep that confirms that Dxo mark…got it right also….Makes you look like…..fill in the blanks..and the ten that agreed with you….just goes to show us all…some have zero clue.

  • Karl

    Dear Roger! All these MTF tests at Lens Rentals are really quite interesting and helpful in deciding about lenses for anybody with a full frame DSLR or a Sony A7. Is there any reason why smaller sensor systems like M43 or Fuji APS-C are not covered at all? I know that you tested M43 lenses some years ago, but nothing like this since you are testing with OLAF. Is there any technical reason for this?

  • Mike Earussi

    For my work a flat field is very important, and this lens is as flat as a macro. Amazing.

  • Hysz

    wow, ok. Is it possible for you to send me some RAWs? just 2 would do, both 1.4 ISO 100, same distance, same light. You can send me a msg if you agree, thanks.

  • Yair

    Roger,
    Can you please post a comparison of the Sigma to the Milvus , i think this is the most relevant comparison to most of us.
    Thanks a lot for the great work.

  • Lacknafta

    Looks like a super lens and I very much like the article, with the initial explanation that lots of glass has a price in weight where specially shaped glass has a price in money. I really liked the original Sigma 85 1,4 HSM on my A77, optically. The focus ring was a bit too resistant to being turned when mf:ing though and the AF was a lama being sick on yoyr shoes (it needed different micro focus adjust depending on whether coming from mfd or infinity). It also made a sort of whistling sound when AF:ing. I asked Sigma’s Swedish official repair channel about it, saying the AF accuracy issue was having a party in my attic and they said they could calibrate it but only from one direction.

  • Hysz

    yay, I thought you were sarcastic, but I believed in you [a little]. <3

  • Teemu Kustila

    I know, I was just asserting my support for you 😀

  • Hysz

    That’s what I said, but top comments are butthurt that 3rd party lens is ‘the best’ lens. Notice the ‘ ‘.

  • Teemu Kustila

    Yep, pretty much confirms DxO tests

Follow on Feedly