Roger Buys a Camera System: A 24-70mm System Comparison

Posted by

Note: I'm going to bore people for a week or two while I decide on a new camera system for myself. To alert those who are going to be bored by posts about "Roger Buys a Camera System"; I'll put that in the title for the rest of this series. 

I don't own an SLR - I go check one out for 'testing' when I need one. But I've moved out to the country and I want a camera at the house. I can't really justify to management that I need to test a camera and some lenses for a year or two.

I know what I want: the Canon T4i's touch screen, the Canon 6D's Wi-Fi, and the Canon 5D Mk III's autofocus built around the Nikon D800E sensor, Nikon's flash systemPentax's user interface (I'd take their sensor too, if I went crop frame), and be able to mount lenses from all manufacturers. But given a far-less-than-unlimited budget, I'll be making some compromises, like everyone else. In order to make comparisons, I want to take a look at exactly how some systems differ.

Most of that doesn't involve geek stuff like this, but geek stuff is what I know best so that's where I'll start. Resolution isn't the end-all point for deciding on a camera system. It isn't even the most important point in my decision about a camera system, and I'm a resolution nut. But it is a thing I want to know about.

A Resolution Comparison

One of the things I constantly harp on is that people should not compare Imatest or DxO results on two different cameras. You can't look at the results of a lens on a crop sensor and a full-frame, for example. You can't look at results of a lens test on a Canon 5D and make good predictions of how it will behave on a Canon 5D Mk III. We've even found lately that you can't take the results on a Sony NEX-7 and extrapolate to a Sony NEX-6.

But there is one thing you can do fairly reasonably. You can compare two systems (camera and lens) to each other and determine the overall resolution of each system. I had some pretty self-centered reasons for doing just that. I, the ultimate camera system commitophobe, am going to have to buy, with my own money, a camera system. I hate when that happens.

Lensrentals.com, 2013

One of the first compromise questions I had involves shooting with 24-70mm f/2.8 lenses; this is my most commonly used lens. The highest resolving 24-70mm f/2.8 lens is the Canon 24-70 f/2.8L II. The highest resolving camera is the Nikon D800E. Since I can't mount the best lens to the best camera, I thought I'd look into how the two systems compare in final resolution.

I was fairly certain the D800E with a good Nikon lens is going to be better than the 5D Mk III with the great Canon lens. But I wasn't sure by how much. The other nice thing about working at this focal length is we have a similar lens we can mount to either camera, the Tamron 24-70 f/2.8 VC, to get a little further comparison.

Let's Look at Just the Lenses

Before we begin, I know there are some Fanboys somewhere who have stopped payment on their reality check and are stabbing pins in their Roger Effigy Doll because I said the Canon 24-70 II is the highest resolving f/2.8 lens. So let's take the camera out of the equation and compare just the lenses on our Well's Optical Bench. This means no camera mount, just evaluating the lens itself.

The following are MTF vs frequency plots for the center of the lenses in question - again, this is not Imatest data using camera images, this is purely assessment of the lenses (at infinity focus). The separation of the two graph lines shows the astigmatism of the lens. Almost all lenses have some; the Canon is truly unique in having so little. (These graphs courtesy of Aaron Closz who still gets nervous when I play with the optical bench. It's nice and predictable, though. If I want him to run some tests all I have to do is sit down and say, "where's that 70 micron reticle?" and here's there like magic.)


MTF (vertical) versus frequency (horizontal) of Canon 24-70 f/2.8 Mk II @ 50mm


MTF (vertical) versus frequency (horizontal) of Nikon 24-70 f/2.8 @ 50mm


MTF (vertical) versus frequency (horizontal) of Tamron 24-70 f/2.8 VC @ 50mm


From direct comparisons we've known the Canon 24-70 II had a higher MTF 50 than the Tamron on Canon cameras, and that the Tamron was nearly as good as the Nikon on Nikon cameras. The optical bench shows a bit more differentiation between the Nikon and the Tamron than I expected, but otherwise clearly demonstrates what we already knew. I should mention we tested 2 copies of each, all of which had already been tested using Imatest and shown to be good copies.

System Testing

Now let's add the camera systems into the mix, something Imatest is perfectly set up to do. We're going to measure Imatest MTF in line pairs / image height, as always. Since the D800E has 4912 pixels of image height compared to the Canon 5D III's 3840 pixels the Nikon should resolve somewhere around 1.2 to 1.3 X the Canon's resolution if the lenses were equal. (Several other factors, including that the Nikon does not have an AA filter, lenses aren't perfect, and the math is more complex than a simple ratio, make this a very rough estimate.)

Let's start by comparing the Tamron 24-70 f/2.8 VC on the two different cameras. We shot two copies on two bodies and averaged the results (which, btw, were nearly identical) to show MTF 50 in the center, averaged across the entire lens, and averaged in the 4 corners at f/2.8 and f/4.

These tests are all done at 50mm. I just didn't have time to set up at multiple focal lengths and 50mm is a strong area for all 3 lenses. I wanted to compare them at their best.


Tamron 24-70mm f/2.8 VC on Both Cameras

Center MTF50Average MTF50Corner Avg. MTF50
Canon 5DIII f/2.8810665350
Nikon D800e f/2.81085855445
Canon 5DIII f/4940710445
Nikon D800e f/41225955560


The MTF50 difference between the two cameras shooting the same lens is quite apparent. The difference is a bit greater in the center and a bit smaller in the corners but it is quite significant - as we knew it would be.

Canon 24-70mm f/2.8 II vs. Nikon 24-70mm f/2.8

Now let's compare the Canon camera with the Canon 24-70 f/2.8 Mk II to the Nikon camera with the Nikon 24-70 f/2.8 AF-S. The better Canon lens should offset some of the Nikon camera's superior resolution. That is exactly what happened.

Center MTF50Average MTF50Avg. Corner MTF50
Canon @ f/2.81000860450
Nikon @ f/2.81170945500
Canon @ f/41060910505
Nikon @ f/412401000570


The higher resolution of the D800E makes the resolution of the Nikon system superior to the Canon system, although the difference isn't as great as it was when we compared identical Tamron lenses. No real surprise here. Also not surprising, the Nikon lens is slightly better than the Tamron, although this is fairly close.

The real bottom line here is that there are no losers. The resolution numbers all of these combinations show are nothing short of amazing. For example, all three zooms are equal to, or slightly better than, the superb Zeiss 50mm f/2 Makro Planar at equal apertures on the same camera.

I'll show the f/2.8 data as our usual graph with center resolution on the horizontal axis, average on thevertical, all in line pairs / image height. I think this shows fairly well the actual resolution difference between the cameras (compare the two Tamron results) and the degree to which a better lens closes the gap.


MTF50 (LP/IH) at f/2.8


There's one other aside that is probably worth mentioning; the test fairly well confirms common wisdom. If we run SQF numbers on these resolution differences, it suggests we'd need a print size of about 11 X 16 to detect this resolution difference. At that print size we should be able to tell the Tamron mounted to 5DIII (worst performer) from the Nikon 24-70 f/2.8 on D800E (best performer) pretty clearly. We might detect the difference between the Canon 24-70 Mk II on the 5DIII and the Nikon on the D800e. On a 16 X 20 print the Canon - Nikon difference would probably be clearly apparent.

So What Did I Learn Today?

Not too much. Like everyone else I already knew the D800E with a good lens was going to out-resolve the 5D III with a great lens, but that I'd need a reasonably large print to see the difference.

It also demonstrates another thing I mention a lot: the value of any third party lens varies according to what camera you shoot. The resolution difference between the Canon and Tamron 24-70 lenses is greater than that  between the Nikon and Tamron. Right now, the price difference reflects that: the Nikon costs $600 more than the Tamron, the Canon $900.

But if you want to look at it another way, the Tamron on a D800E is about the resolution equal of a Canon Mk II on a 5DIII -- a bit sharper in the center, not quite as sharp in the corners, but pretty even. The Tamron-Nikon combination (for a guy like me looking at shelling out some major bucks soon) is $1,000 cheaper than the Canon-Canon system.

Of course, all of those prices are going to settle a bit differently in a couple of months. This is just where they are right now. And resolution is just one factor that goes in to choosing a piece of kit.

As to my ongoing search for which camera system I'm buying into, this just answers one tiny question. I've got a lot more research to do. I expect you'll be reading more about that soon.


Roger Cicala and Aaron Closz


January, 2013





109 Responses to “Roger Buys a Camera System: A 24-70mm System Comparison”

matrox vietnam said:

I take pleasure in, cause I discovered exactly what I was looking for. You have ended my 4 day lengthy hunt! God Bless you man. Have a great day. Bye

Ruaal said:

Hi Roger,
I have a Canon 50D and was looking to buy a Canon 24-70 f2.8L USM lense for wedding photography.
Have you ever compared this lense with a Tamron and/or Sigma of similar specs on a 50D and if you have, what are your recommendations also considering the price difference?

Your help with this will be greatly appreciated.

LensRentals Employee

Roger Cicala said:


On the 50D I'd probably prefer the Tamron. It's equally sharp with the 24-70 Mk I and IS is useful to have sometimes. The Sigma is not as sharp as the other two.

That being said, on a 50D I'd really prefer the 17-55 f/2.8 IS unless I thought an upgrade to full-frame was in my future, or I just really needed to get to 24mm. I use the wider end a lot, 24 just isn't that wide on a 50D, but also like the cost savings. That's just me though.


Marcia Salazar said:

I always thought that DSLR cameras are the best types of cameras out there but when I saw what the Fuji X-E1 can do, I immediately fell in love with it. I realized that there are more good cameras out there if only you know how to look but it also depends of your preference.

K said:

Nikon D600 + Nikkor 24-70 f2.8 and Nikkor 70-200 f2.8 VR II vs. Canon 6D + Canon 24-70 f2.8 II and Canon 70-200 f2.8 IS II


I’d like to kindly ask for your views on a decision very similar to the one you’ve made recently. I’d like to decide between the Nikon D600 and the Canon 6D, and two-three lenses (initially) for each.

The question is, what gives one better image quality: a higher quality sensor with great lenses (Nikon D600 + Nikkor 24-70 f2.8 and Nikkor 70-200 f2.8 VR II) or a somewhat lower quality sensor with somewhat better lenses (Canon 6D + Canon 24-70 f2.8 II + Canon 70-200 f2.8 IS II.) In other words, what makes the bigger difference here, the Canon’s better lenses or the Nikon’s better sensor?

The photography I do:
I shoot people / portraits at parties in low light and shoot catwalk fashion shows (also often in poor light, sometimes in good light.) You could call my photography “fashion” and “wedding” photography.

Also, at parties, I often hand my camera to friends to get my own shots. These friends often cannot hold a shot even at 1/30s with IS turned on. I also frequently need to do heavy cropping on these images (the ceiling in particular, while my feet are chopped off…) A higher resolution image to start with helps.

Advantage Nikon here: 24 Mpx v.s 20 Mpx and a Dynamic Range that is 2 EVs broader.

Lenses I’m planning to (initially) buy if I go Canon:
• Canon 24-70 f2.8 II – better than the Nikon equivalent. (Seems significantly better than the Tamron 24-70 f2.8, so I’m not as tempted by the Tamron’s IS and lower price if I go Canon.)
• Canon 70-200 f2.8 IS II – better than the Nikon equivalent. (Seems significantly better than the Tamron 70-200 f2.8, so I’m not as tempted by Tamron’s lower price if I go Canon.)
• Canon 85 f1.2 II – a Nikon equivalent simply doesn’t exist. (I’m debating whether I really need this lens / how practical it actually is. If it cost $400, I would not be debating it, I would just buy it. But at $2,000, I’m debating it, and may go for a cheaper portrait lens eventually. The existence of it as an option is nice.)

Lenses I’m planning to (initially) buy if I go Nikon:
• Nikkor 24-70 f2.8 or Tamron 24-70 f2.8 (Image Stabilized) – there difference in optical quality seems small, and Tamron’s IS would help me (my friends holding my camera while photographing me) in low light at parties.
• Nikkor 70-200 f2.8 VR II or Tamron’s latest 70-200 f2.8 SP Di VC USD – the difference in optical quality seems small, and the Tamron is cheaper, so I’m tempted by the Tamron.
• Nikkor 85 f1.4G or Nikkor 85 f1.8G – both great lenses, but not quite as cool as the Canon 85 f1.2 II

Future proofing / long-term system considerations:
• It seems Canon may be years (?) behind Nikon/Sony in sensor technology in the following two respects:
o DR: the dynamic range of the Nikons is 2 EVs better.
o AA filter: Nikon also seems to be one or two years ahead in terms of eliminating AA filters. (Is this right?)
• The D600 already has AF in Live View while shooting video. The 6D doesn’t have that.
• IS/VR in the 24-70 f2.8: there is a chance that the updated version of the Nikkor 24-70 f2.8 (perhaps coming out later this year, perhaps not coming out for a couple more years) will have IS/VR built in following Tamron’s lead. Canon’s 24-70 f2.8 Mk II just came out last year without IS. That lens will probably not be updated for many years.

Thank you for all your thoughts!


LensRentals Employee

Roger Cicala said:


The answer for resolution is better sensor and lesser lenses give better IQ than better lenses and inferior sensor. But for that difference to show you'd be talking D800 and Nikon lenses versus 6D and Canon lenses. With the D600 as the camera, the advantage, although slight, would be to the Canon camera and lenses. However, the resolution difference is slight enough that for purchasing decisions I'd call it even and look at other things.


Nicolas said:

To whoever passes along in this old forum post: I can confirm that the battery drain issue on the EOS6D comes from the lens, and that Tamron (kindly) fixes the issues rapidly.

I had the issue here in Europe, it went back & forth to Tamron and it's now history.

I had promised to come here and post feedback, so...

Nicolas said:

let's be precise: "the lens" is the new Tamron 24-70 VC

Catalin said:

I just want to see some Nikon D600 (D3X) numbers here for a better point of view between camera&lens. Is it better a D600 than a 5DMkIII with Tamron 24-70?

Thanks for sharing your hard work!

Leave a Reply