Lenses and Optics

MTF Tests of the Sigma 35mm f/1.2 DG Art

We just finished testing a couple of 35mm prime lenses and came away quite impressed. But it took a little longer to finish testing the one everyone had been asking about; the Sigma 35mm f/1.2 DG Art lens. I declared the Tamron 35mm f/1.4 SP the sharpest 35mm lens we had tested just a week ago, so we were all curious if that title would hold up after the Sigma was tested.

So curious, in fact, that I broke the MTF Testing Rule I Always Refuse to Break. I actually tested the Sigma at both f/1.2 AND at f/1.4. Why did I finally break the rule? Cause I wanted to. Will I break it again, if you ask nicely, have a really good reason, and are on a Holy Quest? Nope.

Let’s take a second to do a quick comparison of the Sigma f1.2 with other 35mm wide-aperture prime lenses (including some for other mounts, because a lot of people are shooting other mount lenses on Sony cameras).

LensPriceWeight (g)Length (mm)
Sigma 35mm f1.2 Art$1,4991090136
Tamron 35mm f1.4 SP$899
815105
Sony FE 35mm f1.8$74828173
Canon 35mm f1.4L II$1,699760105
Sigma 35mm f1.4 Art$69966594

Obviously, if the widest aperture isn’t that important, the Sony FE 35mm f1.8 provides a much smaller lens with great image quality at a cheaper price. A lot of you may not realize the Sigma 35mm f1.4 Art is the least expensive option, yet still provides superb resolution. The Tamron 35mm f1.4 SP was recently declared (by me) to be the resolution champion at this focal length and is an awesome bargain at its price.

The Sigma 35mm f/1.2, though, gives you f/1.2, and some of us, at least, lust after f/1.2. You pay a price for f/1.2, both in dollars and in lens size. The question really is, as we say in the South, so what all comes with that? Because we all know a lot of f/1.2 lenses are ‘wide-aperture, hold the sharpness’.

A Quick How to on Reading MTF Charts

If you’re new here, you’ll see we have a scientific methodology to our approach, and use MTF charts to measure lens resolution and sharpness. All of our MTF charts test ten of the same lenses, and then we average out the results. MTF (or (or Modulation Transfer Function) Charts measure the optical potential of a lens by plotting the contrast and resolution of the lens from the center to the outer corners of the frame. An MTF chart has two axis, the y-axis (vertical) and the x-axis (horizontal).

The y-axis (vertical) measures how accurately the lens reproduces the object (sharpness), where 1.0 would be the theoretical “perfect lens.” The x-axis (horizontal) measures the distance from the center of a lens to the edges (measured in millimeters where 0mm represents the center, and 20mm represents the corner point). Generally, a lens has the greatest theoretical sharpness in the center, with the sharpness being reduced in the corners.

Tangential & Sagittal Lines

The graph then plots two sets of five different ranges. These sets are broken down into Tangential lines (solid lines on our graphs) and Sagittal (dotted lines on our graphs). Sagittal lines are a pattern where the lines are oriented parallel to a line through the center of the image. Tangential (or Meridonial)  lines are tested where the lines are aligned perpendicular to a line through the center of the image.

From there, the Sagittal and Tangential tests are done in 5 sets, started at 10 lines per millimeter (lp/mm), all the way up to 50 lines per millimeter (lp/mm). To put this in layman’s terms, the higher lp/mm measure how well the lens resolves fine detail. So, higher MTF is better than lower, and less separation of the sagittal and tangential lines are better than a lot of separation. Please keep in mind this is a simple introduction to MTF charts, for a more scientific explanation, feel free to read this article.

MTF Results

For an f/1.2 lens, the MTF chart is really, really good. Center resolution is excellent. Away from center resolution is well maintained, although, there is some sagittal and tangential separation, which indicates either a bit of astigmatism or lateral color. This is expected in very wide-aperture lenses, though, and it isn’t severe.

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Since we’re all used to looking at f/1.4 MTF charts, it’s worth pulling up some other f/1.2 comparisons to show just how sharp this is for an f/1.2 lens. The only other 35mm f1.2 I have data for is the Voigtlander Nokton 35mm f1.2 Mk II. The Voigtlander is an older, smaller, less expensive, manual focus lens so we didn’t expect it to keep up with the Sigma; and it doesn’t.

 

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The classic old Canon 50mm f/1.2L is an f/1.2 lens and while it’s obviously not a 35mm focal length, it’s still worth a comparison. It was never considered a sharp lens, even back in the old days, though. (And before you ask, no I can’t test the RF 50mm f/1.2 yet, so I don’t have that logical comparison available.)

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The sharpest ultra-wide aperture lens that I had tested (before now) at f/1.2 was the Leica Noctilux-M 75mm f/1.25 ASPH. Despite the Leica’s $12,000 price tag, the Sigma is indeed sharper. I was honestly a little surprised at this.

 

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So I think we’ve settled the question as to whether the Sigma is the sharpest f/1.2 that we’ve tested. (From computer-generated MTF charts I do think the Canon RF 50mm f/1.2 will test sharper, but, as I said, I can’t test it yet.)

I Know What You’re Thinking

So, it’s a really amazing sharp lens at f/1.2. Those of you who really need f/1.2 are already off ordering it somewhere. But a lot of people are thinking, well, I’d like me some f/1.2, but I really want to know how it compares to the 35mm f/1.4 lenses. I know it should sharpen up a bit at f/1.4, but how much? So, for this one and only test, because 1) I wanted to know, too; and 2) I had a rare day where the optical bench and I both had nothing else to do; I ran 5 of the Sigma 35mm f/1.2 lenses at f/1.4.

 

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Just slightly stopped down to f/1.4 we have a significant improvement in resolution in the center of the image, but not much change in the outer half. (For those of you who think ‘stopping down improves things everywhere’; no it doesn’t. It’s specific to each lens and depends on which aberrations the lens has. Some lenses sharpen up all over, some in the corners first, some in the center.)

I used those f/1.4 results to do a couple of comparisons to other 35mm f1.4 lenses. We’ll compare it first to the Sigma 35mm f/1.4 Art, which is an excellent 35mm.

 

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The Sigma 35mm f1.2 DG Art is clearly a bit better than the original f/1.4 Art. It is a newer, larger, and more expensive lens. But, I honestly thought the f/1.2 lens would be less sharp than the f/1.4 before doing this test. Because historically f/1.2 lenses have been.

So now the question becomes, is it as good as the Tamron 35mm f1.4 SP, the lens that just 10 days ago I declared the sharpest 35mm we’ve ever tested?

 

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Well, it’s a dead heat in the center. Away from center, if I split a few hairs, the Tamron is a little sharper and it clearly has less sagittal-tangential separation. So the Tamron retains its title of sharpest lens in the Welterweight division.

This is where you ask me ‘could we see that difference in a photo’? Nah. The two lenses would render differently, perhaps have a slightly different color cast you might notice, etc. But even in a large print with a magnifying glass, you couldn’t say one is clearly sharper than the other.

Conclusion

We showed one important thing here. If you want to shoot a 35mm f/1.2 on a Sony camera, the Sigma is a superb solution. Unlike most ‘ultra-wide’ aperture primes, you don’t pay any sharpness penalty to use this lens. That is truly unusual, f/1.2 lenses are expected to be less sharp at the same aperture than f/1.4 lenses.

It’s actually a bit better than ‘as good as’. The Tamron 35mm f1.4 SP is a tiny bit of hair-splitting, pixel-peeping sharper. But the Sigma 35mm f/1.2 is only available for FE and L mount cameras, and the Tamron isn’t available in FE mount (although I’m sure some people will be shooting in with an adapter on FE cameras).

As always, I’m only testing optical resolution. But assuming the AF speed and accuracy, the bokeh, rendering, and other important aspects of the lens please you, this is the sharpest 35mm wide-aperture lens you can natively mount to your Sony camera, and it’s a wider aperture than any of the others, too.

If you don’t care about f/1.2, then the Tamron on an adapter (if you’re an adapter person) is awesome, smaller, and less expensive. The Sony FE 35mm f1.8 will probably be the most popular of this recently tested group; it’s small, native, and reasonably (but not cheaply) priced. The Sony FE 35mm f/1.4 ZA is also a lens that exists, although I can’t imagine anyone is considering buying one.

 

Roger Cicala and Aaron Closz

Lensrentals.com

September, 2019

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 Lenses and Optics
  • Yes, using SLS for now, but I work on both Mac and PC so I’ll probably get around to testing Sequator sooner or later. From what I’ve seen it messes up a bit more often though.

    If you’re stacking at ISO 12800, though, you should probably look into getting a tracker so that you can kick that ISO way down and get cleaner shots to begin with.

  • To print large images and have low noise has forced me into stacking the sky separately from the ground. I often stack the sky in 15-20 shots averaging the noise of 10-12,800 ISO. It gives sharp stars but adds much more difficulty to editing the photo. For the ground images, I stack for noise and this has really changed things for me. But at this point, I can’t say I got in camera because that’s not possible without lots of noise or stars trailing. It has forced me to learn how to blend better in photoshop. Are you using Starry Landscape Stacker or Sequator?

  • Sergey G.

    Thanks a lot. I’m trying to build UWA-WA lens coverage around beautiful Sigma 24-35/2. Probably I should go with couple faster primes. For now in transferring to Nikon process I own two 500mm primes and Nikkor 70-200/2.8. And I need to feel the gaps, but want to do it smartly 🙂

  • Greyser, I’d say it’s not quite as sharp as those two, but close enough that sample variation would largely mask the differences. With 5X zooms there’s going to be a significant amount of variation not just between the lenses, but within one lens at various focal lengths. I’d probably go with whether I preferred the Tamron zoom range to the others.

  • Sergey G.

    Roger, thank you very much for the test. So, it is more of convenient “portrait zoom” as Tamron specified it, than all around lens for every day use.

    How it stands out against, let’s say, Sigma 24-105 or Nikon 24-120? I understand that you just poked into it and did not have enough time to compare them. I just curios about your impressions in general: similar, inferior/superior.

    Thank you again,
    Greyser

  • Greyser, I tested 3 copies of the Tamron 35-150mm. It’s a good 5X zoom, meaning sure not as good as a 3X zoom, but for what it is, it’s good but not special. No paradigms were shifted in the making of the 35-150.

  • Mark Harris

    not again with that BS mount size crap that Canikon tried to push in desperation when people were less than impressed with their lackluster products

  • Yes, all the new SIgmas were very tight. There’s variation, of course, but on the Canon-L range. And I know first-hand Sigma’s doing the best ‘end of assembly line’ testing of anyone right now.

  • BoredErica

    Same for Sigma 40mm 1.4?

  • Sergey G.

    Hi Roger, I really appreciate your reply. I have to confess that I’ve learned about your 3X zoom testing rule before I asked for this (sorry). But… There are some unique examples of greater zooms to be better than lower “x” lenses. Let’s take for example phenomenon of 50-500 “Bigma”. It went through many iterations and every time it was considered better/sharper than Sigma’s 150-500 and 170-500 zooms. 10x vs. 3x. I’ve never had one, preferring long fast primes, however, it is a well known fact among birders. And Sigma did it again with recently released 60-600mm which (according to MTF data what I’ve seen) is sharper then 150-600mm Sport.
    This 35-150/2.8-4 seems to be unique in many ways, challenging most of traditional paradigms. Probably Tamron is paving its own path in highly competitive market. Let’s say almost flawless 15-30/2.8 + 35-150/2.8-4, which is f/2.8 lens at 35-70mm. It is relatively same sized as Tamron 24-70, but lighter a bit and has another 75-150/3.5-4 advantage. What a treat! Or a couple of smaller fast primes on wider end and this… plus 200/4 or 300/4 prime. Quite interesting concepts might be. All available so far info is very contoversial. Some said that the output is on a softer side, while others were truely amazed by 35-150 sharpness along the whole FL range. I guess yours very objective scientific testing of multiple copies may fill the voids perfectly well.
    I very respect your time, but you seem to be very curious man with a hunger for new and unusual things. And it might be real fun! Just trying to convince you to reveal an ultimate truth 🙂

    Thank you agin and hope for the best,
    Respectfully,
    Greyser

  • Greyser, it has been my habit to not test anything greater than a 3X zoom, and to not test variable aperture zooms. I may (may) get that done because it does interest me, but it will be more about ‘oh, I have a week with nothing else to do’ than anything else.

  • A Sigma 85/1.2 may dislocate your lens mount. 😀

  • Sergey G.

    Hi Roger, I’m sorry to highjack this 35/1.2 tread, but I don’t see another opportunity to contact you directly. I’ve been enjoying your posts mixed with solid test data and very humorous remarks.
    There is very new and quite unusual lens in play – the Tamron 35-150mm F/2.8-4 Di VC OSD (Model A043) zoom, which is claimed to be very sharp and generally great. I’m a birder and usually shoot Sigma 500/4 (for 2 years, previously shot Sigma 500/4.5 for 6 years) and Nikkor 500/5.6PF (more like my retirement lens to be eventually). Currently I’m giving up my previous brand (Pentax) 5 bodies and almost 2 dozens lenses, switching completely to Nikon (D500 and D850). So, the initial choice looked quite obvious: 14(12)-24; 24-70, and 70-200. And based mostly on your test results I almost opted out for the Sigma 14-24/2.8, Tamron 24-70/2.8, and Nikkor 70-200/2.8E. I know that you are not a fan of longish zooms. Me too. However, with 35-150 initial f/2.8, and f/4 starting somewhere from FL 70mm, this lens might be a game changer, requiring mostly something like 15(16)-30(35)mm (Tamron, Tokina Opera, etc.) to be paired with for every day casual use and probably outperforming your “f/5.6 best choice recommendation” – the Sigma 24-105/4.
    I just learned that LensRentals now has new Tamron 35-150 in house. Are you planning to test it and compare with closest competitors? I’m pretty sure, many of your readers will greatly appreciate such work.

    Thank you in advance,
    Greyser

  • Paolo Bubu

    Tokina Firin will likely murder everything under 1000$, that lens is fantastic for the price.

  • Paolo Bubu

    Star trackers are great on paper, but I found out that in the real world people are abusing em creating fake looking photos or “impossible standards” often taking a picture in one location and pasting the sky from another, that’s super lame considering one of the coolest thing of the night sky is that it’s basically a giant clock and that it’s great when one is able to combine that aspect with the foreground.

  • Paolo Bubu

    Apart from the higer frequencies (which arguably are less important than the lower ones) the Sigma has more astigmatism than the Tamron, is heavier, bigger and mor expansive.
    To me the Tamron is the winner of the two without doubts, that lens is a jewel!

  • I respect the “get it correctly in-camera” ethos that your partner and you seem to respect. But (and this is just layman curiosity) is shooting and exposing for the landscape separately from the sky while on a star tracker really in contradiction with the desire to shoot something faithfully? (Of course, dropping in the Milky Way on a shot in which it didn’t appear is completely ridiculous—but this doesn’t seem like that at all.)

  • Yes, and especially if you plan to photograph the sky only, and at telephoto focal lengths, a good tracking mount is a must-have.

    However, for nightscape photography, where the starry sky is just a sky above a landscape of course, tracking is an annoying addition of extra gear, shooting time, and post-production. And it’s basically impossible if you’re shooting timelapse, which I enjoy a lot.

    Either way, generally speaking an astro shooter who is shooting tracked will still only stop down a “mere” 2-3 stops, or to f/4 or so, because f/8 is definitely overkill on most lenses. Optimally, an f/1.4 prime stopped down to f/2.8 or f/4 is the best middle ground.

  • Don Farra

    Thank you

  • If and when we get an electronic mount made for them on the optical bench.

  • Very consistent lens.

  • Andy I ran 5; that may have been a chart composed after the fourth. I’ll put the 5th graph up when I get back in town but they’re virtually identical.

  • Don I do not think so; the Sony filter stack is similar to what the Tamron was designed for.

  • Yes, you could, however the landscape will blur a lot during the tracked shot. Matthew (Astro-Landscapes) and I tend to try to do everything in a single shot. It’s a bit of a reaction against the compositing/fakery/just-drop-a-milky-way-in that is all the rage these days in landscape photography. We try to keep everything real.

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