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A 24-105 Comparison

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Sigma has been releasing one great lens after another for a while now. Some, like the 35mm f/1.4 and 18-35mm f/1.8 zoom, have created feeding frenzies soon after (or even before) their release. Others, like the 24-105 f/4 OS, haven't created a whole lot of fuss. So I thought we would do a little optical testing and make the logical comparison between the classic Canon 24-105mm f/4 IS and the new Sigma 24-105 f/4 OS.

As usual, this is not a complete lens review, just a simple resolution test on several copies of each lens. One thing we'll do with this test that we haven't been doing a lot -- we'll test the lenses both with Imatest and also on an optical bench so we can compare performance both at infinity and at closer focusing distances.

Lens Specs

Sigma 24-105 Canon 24-105
Length (in)4.34.2
Width (in)3.53.3
Weight (lb)1.951.47
Filter82mm77mm
Diaph. Blades98
Elements/groups19/1418/13
Price$899$799-$1,149

Not surprisingly, the two lenses are fairly similar, although the Sigma is heavier and takes a larger front filter. I gave a range for the Canon price because while the list price is still $1149, it seems to be on special constantly. You might not always find it for $799 but you can usually find it for well under the list price.

The optical design of the two lenses is quite similar, too. The Sigma has a bit more exotic glass and has a more complex rear group.

Imatest Results

Four copies of each lens were run through our Imatest lab. These copies were selected from our stock, all of which had been previously tested for centering and optical adjustment. Imatest was run at 24mm, 50mm and 105mm focal lengths on print (as opposed to transparent) SFR Plus charts. Testing distances were 7 feet for 24mm, 15 feet for 50mm, and 17 feet for 105mm (different chart sizes used), and were performed on a 5D Mk II body.

I'll start with a summary chart showing the results for each lens at each focal length tested. Center, weighted average (horizontal and vertical readings at 13 positions), and corner (average of all 4 corners, horizontal and vertical) are listed. The number in the table is the average (mean) of that reading for the 4 copies tested.

MTF50 Ctr MTF50 avg MTF50 cornerDistortion
Canon 24mm9657754003.5% bar
Sigma 24mm10709003952.4% bar
Canon 50mm9707804602.4% pin
Sigma 50mm9458054451.75% pin
Canon 105mm7456004002.0% pin
Sigma 105mm7956204251.85% pin

One other thing that the table shows is that the Sigma has a bit less distortion than the Canon.

Before you start dissecting those averaged numbers, let's look at a graph of the individual lenses. Remember, these are all selected from a pretested group so none are decentered, but sample variation in a 4x zoom is a very real thing.

(Just because someone always asks, one copy isn't necessarily better than another. One is a bit better at the long end, another at the wide end, one has slightly better centers but slightly weaker corners, etc. Whenever someone asks me to select a 'best copy' of a zoom, I tell them those have to be delivered by a Leprechaun riding a Unicorn.)

 

 

 

I think the graph simplifies the discussion quite a bit. Both lenses are about the same in the middle of the zoom range. Both are not quite as good at 105mm as they are in the middle of their zoom range, although they're certainly acceptable at 105mm.

There is one (probably) significant resolution difference between the two lenses: the Sigma is sharper at 24mm. How much sharper? Not as much as the decrease in sharpness at 105mm for both lenses, but probably enough to notice. Or looked at the other way, if you don't notice the difference in sharpness between 50mm and 105mm, you sure won't notice the increase at 24mm.

But the difference is real and if you pixel peep you might notice the Sigma is a bit sharper than the Canon at 24mm . . . except . . .

But Wait, There's More!

Computer target analysis (Imatest and DxO) has become the standard for internet lens testing and reviews: they're relatively simple, affordable, and give a lot of information. But they have a limitation that sometimes worries me -- because of chart size limitations wide-angle lenses have to be tested fairly close to the chart. In the case of a 24mm lens the testing is done at 7 feet (and that's with the largest Imatest chart available).

So I thought this would be a good time to repeat the tests using our Wells Optical Bench. Optical benches have some limitations too, but they test the lens at infinity. In this case the optical bench tests show one difference compared to the Imatest results.

The images below are optical bench print outs for one example of the Canon and one of the Sigma lenses at 24mm (we tested them all, they all are very similar).

 

The black, blue, red, and green lines represent MTF10, 20, 40, and 60 with values on the vertical axis. The horizontal axis shows degrees from the center of the lens. There are two lines of each color, showing tangential and sagittal rays. The difference between the two lines of the same color shows the amount of astigmatism.

Optical bench printouts can be a bit confusing when you aren't used to them, so I'll summarize a bit. Notice first that the Canon has no astigmatism in the center. The Sigma has a bit of astigmatism in the center, zeroing out about 4 degrees off center. (Note: all the copies tested for each lens showed the same pattern. This is the way it was designed. There are advantages and disadvantages to it.)

If we take the Optical bench values for the 4 copies at 24mm and put them in a table, it's different than what we saw with Imatest.

Sigma ctr Canon ctr Sig 24 deg Can 24 deg
MTF100.960.960.9250.93
MTF200.930.940.840.86
MTF400.870.880.720.75
MTF600.810.820.540.59

There are some minor differences between the two lenses at 24mm at infinity (the Canon actually has slightly higher numbers, but the difference is completely insignificant). I won't bore you repeating the optical bench tests at 50mm and 105mm. They were identical.

The Imatest results are correct; the Sigma is a bit sharper at 24mm when shot at close focusing distances. They simply don't tell the whole story. At longer focusing distances the lenses are identical.

Conclusion

Sigma has made a very nice zoom here at a very good price. It's obviously not going to create the stir that occurred with their 35mm f/1.4 or 18-35 f/1.8 lenses, but it's a nice addition to their lineup.

Canon shooters who have a 24-105 f/4 IS have no reason to change based on optics as long as the promotional pricing remains in effect. The Sigma and Canon 24-105s are nearly identical. Similarly the Nikon 24-120 has been available on discount lately, so I don't see a big motivation for Nikon shooters to change, either.

Of course, if the pricing changes I wouldn't hesitate to buy the Sigma instead of the name brands. If nothing else, I think the presence of the Sigma will keep Canon and Nikon prices reasonable.

I expect as this lens is released in other mounts it will be quite popular. There's a reason Canon has sold about 3 gazillion 24-105s. It's a very good lens with a very useful range. The Sigma will be available for Sony shooters next month and may be the best option in that mount.

I'll repeat the more general point in the conclusions, though, because I think it deserves repeating. When you look at computer-target test results remember they are valid at the distance tested. With wide-angle lenses, particularly, that doesn't mean those results are valid at longer focusing distances.

I'll add that it's about time testing and review sites start adding the testing distance when they write their reviews. With 16mm lenses, for example, test results are generally at 4 feet. Those tests may not mean a lot when you're shooting landscapes at infinity with that lens. 

Roger Cicala

Lensrentals.com

March, 2014

31 Responses to “A 24-105 Comparison”

Speed said:

Every time Canon releases a new more expensive version of a popular lense I think that it's about time for a 24-105 Mk II. This new Sigma lens shows that maybe there isn't much room for improvement at this price and focal length. And I guess that nether Canon nor Sigma think that there is much demand for a more expensive design -- an f/2.8 for example.

CarVac said:

How on earth does astigmatism even exist in the very center? There is no 'saggital' or 'meridional' to speak of. I understand when sliiightly off-center, but not in the very center.

LensRentals Employee

Roger Cicala said:

CarVac, with these machines center is not a pinhole, it's a line of fixed length, 1.5 microns thick, 25 microns long. The exact center of the lens will be boxed by these lines when the measurement is taken. The MTF measurement is slightly different depending on line orientation, or thought of another way the best focus is slightly different depending on line orientation.

I understand what you're saying since in theory 'center' is an infinitely small pinhole, but testing reality doesn't include an infinitely small reticle :-)

Roger

CarVac said:

So it's more like the astigmatism of a human eye? Perhaps the curves wouldn't intersect if you did the test with the lenses rotated 90 degrees, with one line being strictly lower than the other.

LensRentals Employee

Roger Cicala said:

Not sure I understand, Carvac. We do rotate the lenses through 90 degrees, it's one of the checks we do with that type of testing.

L.P.O. said:

Very interesting to see the performance differences at different test distances.

Thanks, Roger!

Joachim / CH said:

I got the Sigma last week. As you said, nothing that mindblowing like the 35 and 18-35, but far better than my previous Nikon 24-85. It's very flare-resistant and the short 0.45 m distance at 105mm is very close to the Micro Nikkor 105/2.8.

Unfortunately the distance is not the only thing very close to that lens: at the moment all my Nikon bodies with AF-adjustment abilities do recognize the Sigma as this Nikkor 105/2.8 which is kind of difficult as both lenses need different adjustment and I don't want to use the Sigma dock to counter-adjust. On the bright side, there's very little AFA necesary for the Sigma, +2 will do, and I could switch AFA just off until Sigma releases a firmware with a fix. I'm sure there will be a fix, but at the moment owners of those two lenses need to workaround.

Lasse Beyer said:

Who's connnie with three 'n'? ;)

Phil Lurkin said:

Roger, what can you say about the actual transmission of the lens? I mean, from what I've seen on the web lenses from OEMs hardly ever come close to the transmission they advertise; e.g. canon 200-400 f4 is actually t/4.7 and the nikon 58 f1.4 is t/1.7 in reality. Isn't that (almost) half a stop? Whereas the sigma 18-35 f1.8 is t/1.8-1.9 at all focal lengths!
If the same is true for this one as well, this lens is faster by almost half a stop, right?

LensRentals Employee

Roger Cicala said:

PHil, I'm glad you brought that up because I failed to mention it in the article. The Sigma was about 1/2 stop faster than the Canon throughout the zoom range.

Roger

Phil Lurkin said:

Thanks Roger! That's really useful. But I keep wondering how they do it. And why Nikon and Canon can't!

Phil

pheroze said:

Hi, i hope this is something to consider for anyone intending to purchase the canon 24-105. I've had the lens for just over a year and shot under 800 pictures with it.It started showing up an Error 01 display on my camera suggesting i clean my lens to camera contacts. Still no good after a clean so i sent it for repairs. The diagnosis :diaphragm malfunction +image stabilisation malfunction. £300 to fix.I am a very careful user.Its had no bumps or falls.Looked up the internet and found lots of similar reports. Clearly a design or manufacturing issue but Canon wont take responsibility.And this an L lens not a kit one. Buyer beware!This raises another issue about reviews. I never see long term reliability reports about cameras and lenses just first impressions and tests.p.k. u.k.

gaelv said:

Personally owner of the 24-105 canon lens since 5 year (as well as other lenses, 24-70, 50, 135, 85, 70-200, 28-300,...), I had no problems, errors or whatsoever. I own also different sigma lenses (12/24, 20, 120-400, 70-200...) which I do also love. But for me the 24-15 is a "walk around lens" and this is why, what I do most consider in this case, is the weather sealing. And what I do most regret is that manufacturers do not always seal their lenses...

Brian said:

Thanks for the comparison Roger. I've been looking all over for one online, and I'm glad the person to do it was yourself.

I'm renting a normal zoom for my fall trip to Disney World, and I'm torn between Canon 24-70 f/4L IS, and Sigma 24-105mm OS. They're the same price, and the same speed (although the Sigma may have a real-world T-stop advantage.) Which lens would be sharper in more focal lengths and focus differences.

Thanks!

Rob Smith said:

Sigmas should have made this a faster lens (maybe even 3.5 to keep the size down) or made it slightly wider or longer to distinguish it from the Canon product. That would have started some defections from Canon lens owners. That's one reason why the 18-35 has been selling out. On top of being a high quality lens, it's the only zoom lens in 1.8. Unique.

LensRentals Employee

Roger Cicala said:

Brian, I think it would be pretty much a wash from 24-70. The Sigma will give you some extra range, the Canon the macro feature (although I can't see that being much help at Disney).

One thing I would add, though, is to wait for some real-world reviews of the Sigma as far as low-light focusing. That may be critical at Disney and it's something I don't have the ability to test accurately.

Roger

Joachim / CH said:

Macro feature of the Canon? I read the minimal distance is 45 cm. So is the Sigma's as well. Do I miss something?

Joachim / CH said:

Ah, sorry: the 24-70's macro feature. But at 0,38 cm I gain 16% closer distance and loose 50 % focal length (70 + 35mm). So, in total the Sigma delivers a greater scale, doesn't it?

Claudio Costerni said:

So, the different 'gost & flare' resistance (that seem better for this Sigma 24-105/4), could do the only important difference ...

John Pra said:

Hi Roger,
How is the autofocus accuracy in indoor with low light situations usage? I have a bad luck with third party lenses. The popular SIGMA 18-35mm f/1.8 never get perfect focus in my 7D nor 6D (at 35mm) just like what DPREVIEW found out. Even after got a replacements still misfocus a lot and at f/1.8 it becomes useless, so I return it. The potential sharpness is completely wasted. The dock can fix part of it but not most of it since it only has 16 points corrections meanwhile focus and zoom gives unlimited combination settings.

LensRentals Employee

Roger Cicala said:

Hi John,

You'll have to ask one of the reviewing sites about that - not something I have the expertise to compare, and with third party lenses it's so camera specific that generalizations are nearly impossible anyway.

Pedro Claro said:

Thank you, Roger and LensRentals for the comparision.

Some comments...

I owned a 24-105L IS until about a year ago, and decided to sell it for a Sigma 35/1.4, going all primes. I had the L for about 4 years and after 3 years of careful, non-professional and moderate use it also developed the feared 01 error, resulting in a +200€ repair. This was quite disapointing and one of the reasons for selling it.

After about one year of an all-prime setup (21-35-50-100-135), I'm starting to think about getting, again, a good and versatile walk-around zoom. 24-70L II is way out of my budget, and I'm not that keen on the Tamron 24-70 VC (although I've had excellent Tamron lenses in the past), so I'm narrowing my options to 24-70/4L IS, 24-105 OS and... 24-105L IS. I need to decide if I prefer the slightly better IQ of 24-70/4L IS or the more versatile range of focal lengths of the other two.

Between both 24-105 lenses, it seems that the deciding factor could very well be the rendering. If the Sigma has the same drawing style as the Sigma 35/1.4, that could be a good starting point to me, although I'm still trying to decide if I like the way it renders (sometimes I love it, having some resemblances with 'Zeiss pop', but sometimes I don't like it that much). Canon 24-105L IS has a much more predictable rendering, but a somewhat less vibrating one.

Considering the IQ of the A-series lenses Sigma has been releasing, it's a bit disappointing this 24-105 OS 'only' matches the reasonably old and not particularly notable design of 24-105L IS. Maybe, as someone said before, it's hard to improve at this price point.

john pra said:

The price of 24-105mm IS is about $650 new from someone resell the kit lens. It is very hard to beat and Sigma has to lower the price significantly well below $600 to attract more buyers.

For travel and vacation, With this era of 25600 ISO, 24-105mm IS is very versatile than anything in the market and deadly reliable for the past 6 years (Rio, Corsica, Rocky Mtn, Smoky Mnt, Java). I usually also bring 70-200mm f/4 IS, 85mm f/1.8 and small flash with my toploader 75AW + lowepro 3 for hiking and those setup is light enough for less than 2 kg.

john pra said:

The price of 24-105mm IS is about $650 new from someone resell the kit lens. It is very hard to beat and Sigma has to lower the price significantly well below $600 to attract more buyers.

For travel and vacation, With this era of 25600 ISO, 24-105mm IS is very versatile than anything in the market and deadly reliable for the past 6 years (Rio, Corsica, Rocky Mtn, Smoky Mnt, Java). I usually also bring 70-200mm f/4 IS, 85mm f/1.8 and small flash with my toploader 75AW + lowepro 3 for hiking and those setup is light enough for less than 2 kg.

Travis Vaughan said:

I have a Canon EOS 60D. I'm looking for a 24-105mm f/4 lens. Since I don't have the Canon lens (although I've rented it from LensRentals.com several times) which lens would you purchase? The Canon model that's been out for a long time or the new Sigma model?

LensRentals Employee

Roger Cicala said:

Travis, if you can get it for similar price, I'd go with the Canon. It's got a long history of being quite reliable. If there's a big price difference, I wouldn't hesitate to go with the Sigma, though.

Filip Carlan said:

Roger, can you confirm the lens locks up when mounted on a Canon 6D with internal GPS enabled and the camera coming out of sleep mode?

LensRentals Employee

Roger Cicala said:

Filip, not yet, but I'll have a tech check it later today.

Roger

LensRentals Employee

Roger Cicala said:

Filip, I can confirm now - several lenses on several cameras and they all did it.

Filip Carlan said:

Thank you, Roger. Hopefully the issue is fixable by just a firmware update.

wil matthews said:

I'm a real fan of the Sigma lenses mentioned here. But I find they don't have same contrast as Canon- in my unscientific study of field use. This is especially true of the 24-105. Also, autofocus is not always as quick. But I trust the Sigma build better.

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