MTF Testing for the Sigma 24-105mm f/4 DG OS HSM Art Series Lens

I generally let you know what my expectations are before I start, to hopefully let you know where my personal opinion affects things. The fact that I’m just posting tests of the Sigma 24-105mm f/4 DG OS HSM Art months after the lens was released tells you a lot. I’m not excited about testing 24-105mm lenses; it’s almost always ‘another one like the other ones.’

Don’t get me wrong; these are useful and popular zooms for a reason. I’ve owned several and used them a lot. The focal length makes them superb general purpose and walk-about lenses. But designing a zoom that goes from retrofocus to telephoto is a daunting task. My conclusion for almost every one of them has been “decent from 24mm to 70mm and usable past that if you need to.” I didn’t expect anything different from this lens, Art or not.

MTF Tests Sigma 24-105mm Art Series

But the $899 price tag is attractive, compared to $1099 for the Canon 24-105mm IS II or Nikon 24-120mm f/4 ED VR. The weight of 855 grams (31.2 oz)  makes it just slightly heavier than the Canon (795 g) and Nikon (710 g), so the weight penalty isn’t severe like it is with some Art lenses. So my expectation was definitely ‘another one like the other ones’ would be a success, given the lower price tag on the Sigma lens.

Optical Tests


If you don’t know that MTF stands for Modulation Transfer Function (1, 2, 3, 4), then just look at the pretty graphs and remember higher is better, the left side of the graph is the center of the image, and the right side is the edge.

At 24mm

This is really amazing center sharpness for a zoom. It does decrease away from the center but so does every 5X zoom. This is really exceptional performance.

Olaf Optical Testing, 2018

At 70mm

The center at 70mm isn’t quite as great, although that’s partly because the center at 24mm was so amazing. This is a really good MTF curve, though, and performance away from center is better than at 24mm.

Olaf Optical Testing, 2018

At 105mm

And here’s a bit of ‘another like every other.’ Performance at 105mm isn’t as good as at the shorter focal lengths, although this is still pretty good as comparisons will show later on.

Olaf Optical Testing, 2018

Sample Variation

Zooms tend to have a lot of variation, and 5X zooms more than 3X zooms, but f/4 helps keep that under control here. This is actually quite a good performance as far as sample variation goes, particularly at 24mm. This is similar to the degree of variation seen on Canon 24-105 f.4 IS II lenses, which we consider a nice, consistent lenses with limited sample variation.



Olaf Optical Testing, 2018


There is more variation at 105mm, but that is the nature of the beast. Every 24-100+ zoom has more variation at the long end.

Olaf Optical Testing, 2018


MTF Comparisons

The logical comparisons (that I thought of) are to the Canon 24-105 f/4 IS II and the Nikon 24-120 f/4 VR lenses. I’m sure someone is going to ask me to compare it to the Leica 21mm f/1.4 or something, but this made more sense to me.

Sigma 24-105mm f4 OS Art vs. Canon 24-105mm f.4L IS II


The Sigma’s performance in the center of the image is just amazing for a 5X zoom, and it remains better at least halfway to the edge of the image. In the outer 1/3 of the image, there’s not much difference. But the difference in the center of images at 24mm should be noticed fairly easily.

Olaf Optical Testing, 2018


The Sigma 24-105mm f/4 OS Art is still superior to the Canon 24-105mm f/4 II at 70mm, although things are closer. The Sigma also has less astigmatism-like separation between sagittal and tangential resolution, and that remains so all the way to the edge of the image. Generally, that results in a smoother look and better bokeh. (Yes, I realize not many are buying f/4 zooms for bokeh, but it’s worth mentioning.)

Olaf Optical Testing, 2018


The party is over at 105mm for the Sigma, and there’s virtually no difference between the two lenses at this focal length. Neither is as sharp as at shorter focal lengths, but both are still very usable.

Olaf Optical Testing, 2018

So what would you notice in photographs? I’m pretty comfortable you could tell the Sigma is better in the center at 24mm. I think you’d probably find the Sigma very slightly better at 70mm, but you might have to pixel peep a bit to do so. At 105mm any differences you see are just copy variation.

Sigma 24-105mm f4 OS Art vs Nikon 24-120mm VR

This shouldn’t be a fair comparison; the Nikon has a longer zoom range and is a much older design. But it has maintained a good reputation as an excellent walk-around and general purpose lens, and since the Sigma is available in F mount, I thought we should look.


Things are actually more even between the Sigma and the Nikon. The Sigma has better MTF at higher frequencies (fine detail) in the center and maintains a little better MTF away from the center. The Nikon, though, has less astigmatism-like separation.

Olaf Optical Testing, 2018


The Nikon is actually a bit better at 70mm in the center at higher frequencies, with things being very similar away from the center.

Olaf Optical Testing, 2018

105mm vs. 120mm

The Sigma doesn’t reach 120mm, and I don’t have data for the Nikon at 105mm, so this is the only long-end comparison I can do. Again, the Nikon at 120mm is performing at least as well as the Sigma at 105mm, which is most impressive.

Olaf Optical Testing, 2018

Would you see these Nikon-Sigma MTF differences in a photograph? I don’t think so. Sample variation is about as large as the difference between averages; so a given copy of the Nikon may be a little better, a little worse, or exactly the same as the Sigma. I would not choose between these two lenses on the basis of sharpness. There are other, more important, factors to consider.

Stopping Down

NOTE: Sorry to take so long getting these repeated. I took a couple of days vacation and wanted to do these myself and make sure I got them correct. We found the reason first set of graphs was incorrect: the machine had been set to test a different size lens, human error didn’t catch it, and the software didn’t have a built-in check, so it mapped the center 1/2 of the image out as though it was the entire field. The machine has been corrected, the software is being corrected, but the humans, until we can replace them with AI, remain human. We’ll make mistakes. The ultimate mistake is mine – I was more enthusiastic about something else I was doing and didn’t supervise this as closely as I should have. My thanks to those who made comments and pointed out the error. 

In correct stop downs, we do still see dramatic improvement at f/5.6 in the 70mm images, a noticeable improvement at 105mm, but only a slight improvement at 24mm.


Olaf Optical Testing, 2018


Olaf Optical Testing, 2018


Olaf Optical Testing, 2018


Field Curvature

The field of focus curvature gives us a lot of information. When the MTF graph falls off at the edges, we don’t know how much is because the resolution is decreasing and how much is because the field of best focus is moving to another plane.

These are quad graphs: the upper left shows the ‘average’ field (the sagittal and tangential values are averaged). Lower left and right graphs separate the sagittal and tangential fields (which lets you visualize astigmatism to some degree – where the fields don’t overlap there is astigmatism). At the upper right is a difference graph showing you that astigmatism. Remember the plane of center focus is a horizontal line through the middle of each graph. Astigmatism behaves differently in front of, and behind, the plane of best center focus.

Again, this is a single lens, so you’ll notice a bit of tilt in the field. That’s because it’s a zoom and they all have a bit of tilt in the field. Unless it’s dramatic in this test (and none of these are), it’s not noticeable in actual photography.


At 24mm the field is really nice and flat, with just a little bit of curve at the very edges. (Geek MTF lesson – notice how the tangential graph doesn’t stay as sharp (yellow and orange) as the sagittal lines towards the edge of the image? You saw that in the MTF graph at 24mm, too.)

Olaf Optical Testing, 2018


At 70mm we begin to see a little U shaped curve in the field of focus. It’s not very strong, but you could probably notice it in a photograph. (My favorite real-world technique is to focus on a rock in the center of a mowed yard, then run a ‘find edges’ or similar filter on the image. You’ll see the field curvature.

Olaf Optical Testing, 2018


The sagittal cure maintains its slight U shape at 105, but the tangential field changes to a, well, I don’t know. Blob maybe?

Olaf Optical Testing, 2018

So What Did We Learn Today?

Well, my true confession is that I view 24-105mm f/4 lenses as sort of the Minivan of camera lenses; practical, useful, and totally not sexy. I’ll admit I use them a lot, but having one mounted on my camera makes me want a bumper sticker on my bag that says “My Other Lens is a Ferrari” or something.

I’ll also admit it has been a long-term policy of mine to never like any 24-105mm f/4 lens. My highest praise for a 24-105mm to date has been ‘doesn’t suck as much as I expected’.  I’ve never veered from that policy while reviewing lens after lens after lens*. It has become a tradition.

I value tradition, so I’m going to make my summary ‘This is the Best Damned 24-105mm f5.6 Lens Ever Made’.  Because did you see how amazingly good this thing is stopped down to f5.6 at 70mm? That is a remarkable thing for any zoom lens, and even more remarkable for a zoom that ranges from wide-angle to telephoto. Honestly, if you are shooting at f/5.6 I can’t imagine any lens at any price doing significantly better than this.

Even at f/4, the Sigma 24-105mm f/4 OS Art is still pretty amazing at 24mm. That center sharpness really shocked me. I wasn’t expecting that. Otherwise, this is a 24-105mm f/4 image stabilized lens that as good or better optically as any of the others I’ve tested and available at a lower price.

There are always other things that are more important when deciding if this is the lens for you, of course, but you can be very comfortable about the resolution being excellent and the sample variation is small. I’d call it clearly better, from a resolution standpoint, than the Canon 24-105 f/4 IS II. The Nikon 24-120 f/4 VR, though, is aging very gracefully and certainly holds it’s own at f/4.

And yes, I realize I’ve just said ‘this is the hottest Minivan on the market’ but hey, if you need a minivan, you might as well get the hottest minivan. Maybe paint some flames on the side, too.


Roger Cicala and Aaron Closz

February, 2018


* The official lens reviewer terminology is if you’ve tried it once you say “in my experience”. If you’ve tried it twice, you say “in my series of tests”. If you’ve tried it three times, you say, “I’ve seen this in lens after lens after lens.”

Author: Roger Cicala

I’m Roger and I am the founder of 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 Equipment
  • JeffB

    Thank you!

  • Munchma Quchi

    Maybe Sigma snuck in some VW Clean Diesel defeat device like software and the lens knows it’s on OLAF?

    Only one way to be certain – conduct your MTF tests in a moving car at highway speeds.

    PS – thanks RC – good to see some traditional lens testing here with all of the caveats.

  • William Dyer

    LOL! Well, yes, though over a couple of years. I’m only a part-timer camera wise.

  • Doug McEwen

    Lukasz: Wow, that is way too harsh. Surely the better explanation is that although sample variation looks “quite good” wide open per Roger’s measurements above, sample variation becomes a much larger factor at f/5.6, where we know that at least one copy (the one tested above) has incredibly good MTF, and another copy (the one tested by Bryon at TDP) was fairly ordinary – roughly the same as the Canon 24-105. No need to make accusations.

  • Lukasz, that was my first thought, too, so I had the tech repeat them on a different copy and they were the same. But Tinus has a good point — we set the lens to the aperture but don’t measure it. So when I do it I’ll double check that there’s not some weirdness in that, too.

    BTW – I’m never going to consider pictures taken with one copy as a “proof”. I spend too much time furnishing various reviewers, including Brian at TDP, second and third copies that I’ve checked to repeat tests for soft corners.

  • The stop-down tests are single copies at both apertures, so not going to be the same as the average of 10 in the overall tests.

  • almeich

    I would buy a lens based on a test (if the tester is reliable and reputable) provided I like the looks and feeling of the lens. Just like I would buy a car.

    If I had a lens and considered selling it, no test in the world would matter. Only my guts feeling.

  • TinusVerdino

    I would think of actually measuring the aperture to so whether Sigma isn’t cheating and is actually stopping down to F8 😉

  • ?ukasz Moszczy?ski

    Roger, it’s not a April Fools’ Day… Such an improve after one stop it’s simply impossible.

    Here’s one of the proofs that it’s a mistake or a lie:
    As you can see, Canon 24-70 2.8 II is far better then Sigma (at 70 mm, f/5.6).

    If you look at Sigma MTF chart (above; 70 mm, f/5.6) vs Canon (70 mm, f/5.6):
    you’ll understand that you’re wrong.

    Roger, I hope it’s just a prank and you did not do it for the money.

  • Lee

    Some kind of weirdness going on with the stop-down tests? The 70mm f/4 chart looks significantly different from the one we see earlier in the Nikon and Canon comparisons. The 24/4 and 105/4 charts are different too, but negligibly. Were these done at a different time with a different batch?

  • Jerry, I don’t test past f5.6.

  • Jerry Sarmento

    Did you look at f8? Just wondering if it gets better, same or worse?

  • JeffB

    I was hoping to find a review of the Sony Zeiss A 24-70mm f/2.8 somewhere here, and nearly thought I had until I read f4. Any chance that the f2.8 will be reviewed/ Especially as they’ve updated with a Mark II edition.

  • Adam Brown

    hmm, I’ll look forward to your testing report, which will be far more scientific than my naked eye. This isn’t a lens I would typically stop down too much, so probably not a big issue for me. On the other hand, I’m working on my review of the Sony 12-24 now, and I’m astonished at how sharp it is wide open for such a wide angle lens, but I notice that diffraction (or something) kicks in very early, F4-5.6 may be the sharpest it gets. We are getting pretty spoiled — virtually every modern lens is center-sharp wide-open nowadays.

  • almeich

    Having waited so long, a few more days is quite OK with me. Thanks in advance.

  • William, please, please, tell me it was 4 weddings?

  • 4.375 and I rounded up. See time compression above. I’m getting round up compression too.

  • Well, you know at my age, you get time compression. I’ve been referring to things that happened in the 90s as ‘about 5 years ago’ for a while now. I guess I’m getting worse, because last weeks article was ‘about 5 years ago’.

  • Adam, I agree with you, as long as you stay at f/4. But the Sony has some weirdness stopped down.

  • I don’t have Nikon stop-downs because the aperture system makes it very difficult to do stop-down bench testing. But I have the Canon 24-105 I and II and a couple of hundred others. This is SPECTACULAR stop-down performance. The Canon is not close.

  • Adam Brown

    This was my review of the Sony 24-105..

    I took a lot of heat for complaining about the vignetting at 24mm, though I did find it otherwise to be a simply spectacular lens.

  • GuyWith

    I’ve always regretted selling our Honda Odyssey minivan. With the back seats folded down that thing held a TON of gear and never broke down. What was I thinking?

  • Looking at the backend of the blog, it looks like your request will be filled sometime in the next week 🙂

  • Adam Brown

    Curious to see your testing of the Sony 24-105/4… which may actually be the best 24-105/4 ever made..

  • Roger, sorry to be That Guy ™, but as a control reference, do you have f/5.6 MTFs for the Nikon or Canon lenses? Maybe 4-5x zooms are all magical 1 stop down (probably not), or the Sigma is an amazing design. Thanks for posting this: it looks like an amazing lens.

  • Tim Cooper

    What I really want is a nominal f/5.6 zoom that I can shoot at f/8 all the time. Maybe we’re getting closer to that.

  • Athanasius Kirchner

    I know that you’ve been late in posting this article, but, 2012? Damn Roger, that’s a heck of a long time to have kept this thing under wraps. It’s even more fascinating that all these shiny new graphs were being experimented with so long ago 😀
    Seriously, thanks for the article. That behavior upon stopping down is ridiculous, it goes from meh to Art in one stop!

  • obican

    Roger Cicala (from says Sigma 24-105DG OS HSM ART gives you 5x zoom lens performance even though it is much closer to 4x.

  • William Dyer

    I’ve used this lens on a Nikon D810 for several weddings and a funeral, and was impressed with how sharp it was at f 5.6 and f 8. I have no complaints other than its filter size. 77mm would have been nice. But life’s full of trade-offs. When I got the Tamron 24-70 2.8 G2, I considered selling the Sigma 24-105. This test validates my decision not to sell it.

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