# Question: Performance of 24-70 4.0 on 7DII (based on tdp and real world)



## picturefan (Dec 13, 2016)

Dear all,

sometimes I check the lens comparison tool of tdp, which gives me good advice about sharpness of lenses.
Always thougt I understand the findings.

Now there is one thing not quite clear, the comparison of Canons 24-70 2.8II vs. 4.0., which is showing a bigger than expected difference between the two lenses, as you can see here:
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Camera=963&FLI=0&API=0&LensComp=823&Sample=0&SampleComp=0&CameraComp=963&FLIComp=0&APIComp=0

Sure, most people find the 2.8II the sharper lens (to a certain degree) than the 4.0. So, of course, there is only a *small* difference in sharpness between the two lenses on 1DsIII or 5Dr. See here.
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Camera=453&FLI=0&API=0&LensComp=823&Sample=0&CameraComp=453&FLIComp=0&APIComp=0

But when tested on 7DII the difference gets much more significant, the 4.0 is getting " kind of bad" in comparison. 
All tests on tdp with 7DII and 24-70 4.0 are showing not really sharp results with that combo (even 18-55 II is sharper on 7DII than 24-70 4.0). 
Can anybody please explain why that is?
Anybody got some experience with that combo?

Thanx.


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## Mt Spokane Photography (Dec 13, 2016)

*Re: Question: Understanding TDP*

TDP has a forum, why not ask there? This site is not knowledgable about how TDP works, some members may be, like Neuro who knows Brian.


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## picturefan (Dec 13, 2016)

*Re: Question: Understanding performance of 24-70 lens, based on TDP*



Mt Spokane Photography said:


> TDP has a forum, why not ask there? This site is not knowledgable about how TDP works, some members may be, like Neuro who knows Brian.



Yes, maybe need to be more precise in the question, already changed the topic´s name.

Why not ask here? The question is not about TDP in general, it is about lens performance and *experience with Canon 24-70 4.0 on 7DII*.


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## Mt Spokane Photography (Dec 13, 2016)

*Re: Question: Understanding performance of 24-70 lens, based on TDP*

It is true that lenses act differently with different camera bodies, so its always a good idea to see what multiple lens testers reveal and pick lenses that perform well with your body.

Generally, lenses will do much better on FF than on crop, at least as far as sharpness numbers. There are other things to consider, but a person can usually see a huge improvement by going to a FF body of about the same MP. Not always though, there are a few exceptions.


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## sedwards (Dec 14, 2016)

*Re: Question: Understanding performance of 24-70 lens, based on TDP*

Here is a little info about the tests . You are seeing 100% crops so it seem worse than it really is . Read this and you will understand the tests a bit better ---- http://www.the-digital-picture.com/Help/ISO-12233.aspx


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## picturefan (Dec 18, 2016)

*Re: Question: Understanding performance of 24-70 lens, based on TDP*

Thanks for the link. Different testings, different results. That's how it is.
But it's not about the testing technologies, lots of people here seem to love them. Me not . It's about "real life" experiences, because I like to spend more time outside, close to my subjects...

*So, is someone in this forum using a 7DII in combination with the 24-70 4.0??*
I hardly can imagine that the results won't differ to EF18-55II...

a) Do you see any real world differences in your pictures (compared to the cheapo kit-lens)?
b) Do you miss the 70-105 extra range (compared to 24-105)?


Can anyone tell me about his experiences, please?

Thanks, in advance, for some practical answers and happy holidays all!


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## Sharlin (Dec 18, 2016)

Number of (mega)pixels being equal, a FF sensor has physically bigger pixels (photosites). This means that beyond a certain point, sensor resolution is a bottleneck and lens differences become less relevant. The smaller and denser pixels of a crop sensor demand more resolution from the lens as well, the lens becomes the bottleneck. The same holds for high-resolution FF cameras like the 5Ds which has pixel density roughly equal to that of the 7D2.


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## picturefan (Dec 18, 2016)

In that way I tried to understand the results from tdp. 

Does that means that the 24-70 4.0 might be the better performer on 5DIII (21MP, bigger pixelsize) than on 7DII (smaller pixelsize, higher density, more lateral ca's).? (Probably yes!)
And if you look at the tdp-site (5Dr, similar pixel-dens like 7DII), the 24-70 4.0 is, again, performing better on 5Dr. (OK, because of bigger sensor and more pix).

But, I still don't understand which one here (7DII or 24-70 4.0) is the "bottelneck"?


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## neuroanatomist (Dec 18, 2016)

An APS-C sensor is smaller than a FF sensor, and the testing workflow uses a fixed output size. Therefore, the APS-C image must be enlarged more than the FF image. That's why the FF image looks better.


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## picturefan (Dec 18, 2016)

neuroanatomist said:


> An APS-C sensor is smaller than a FF sensor, and the testing workflow uses a fixed output size. Therefore, the APS-C image must be enlarged more than the FF image. That's why the FF image looks better.



I see, that's cropping on sensor level. And cropping (e.g. in post-processing) from an given image, that was already made with an crop-cam, also leads to worse results than cropping an image from an FF-image (because it is cropped 2 times).


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## picturefan (Dec 18, 2016)

neuroanatomist said:


> An APS-C sensor is smaller than a FF sensor, and the testing workflow uses a fixed output size. Therefore, the APS-C image must be enlarged more than the FF image. That's why the FF image looks better.



Does that mean (simplified, of course), that comparing 5DIII and 7DII (both ~ 22MP, crop-factor 1,6) leads, resolution-wise, to 1,6x less resolution with the same lens on the crop-body?

Would it mean that only a 35MP crop-cam can have similiar resolution or quality as the 5DIII (35 = 22*1,6)? 

Hope for all experts out there this seems not be too simple a question...

(if it is so simple, than there wouldn't always been discussions about that topic!)


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## picturefan (Dec 18, 2016)

Sharlin said:


> Number of (mega)pixels being equal, a FF sensor has physically bigger pixels (photosites). This means that beyond a certain point, sensor resolution is a bottleneck and lens differences become less relevant. The smaller and denser pixels of a crop sensor demand more resolution from the lens as well, the lens becomes the bottleneck. The same holds for high-resolution FF cameras like the 5Ds which has pixel density roughly equal to that of the 7D2.



But, still, my main question is about quality of 7DII with 24-70 4.0.

Which one (7DII or 24-70 4.0) is the "bottelneck"?


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## Arty (Dec 18, 2016)

Test shots on a chart are going to be at pretty close distances. While I don't have the 24-70F4, it has been reviewed extensively. Take a look at LensTip or other sites. It has some spherical aberration, which means focus shift as you stop down at close distances. This is more of a problem at the longer focal lengths and close to what you are photographing.
Lenses can perform differently close up and at a distance. 
I have used version 1 of the 24-105L on full frame and crop. The lens works great on a crop camera, as long as you are fine with the range. I find the long end very useful. If you decide on the 24-70, you need to compensate for focus shift close up. I often use a zoom for portraits and like the longer focal lengths (70-105). While the 24-70F4 can be sharp, it does have some limitations. People seem to like it, but I won't trade in my 24-105F4IS, no way.


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## Busted Knuckles (Dec 18, 2016)

picturefan said:


> neuroanatomist said:
> 
> 
> > An APS-C sensor is smaller than a FF sensor, and the testing workflow uses a fixed output size. Therefore, the APS-C image must be enlarged more than the FF image. That's why the FF image looks better.
> ...



inside out and upside down - a 35mp Full Frame would have the same pixel size as the 7dII. What is being attempted is a comparison between Crop and Full Frame. Putting more pixels into the crop would only help if the AA filter and lense could resolve the yet smaller photosites. 

No one has brought up the AA filter. 

I have the v1 24-105 and up to 70 like it very much after that, it is a snap shot lens as it gets soft. If I am doing anything "important" - I don't do weddings so typicall time is not that crushed - I switch to the 70-200. I might be switching to an 85 1.4 if my GAS flairs up.


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## StudentOfLight (Dec 18, 2016)

1) Different portion of image circle is used for creating APS-C image vs full frame image
2) Finer pixel pitch of APS-C will more easily resolve optical imperfections in lenses
3) Some sample variation is possible


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## picturefan (Dec 19, 2016)

Busted Knuckles said:


> picturefan said:
> 
> 
> > neuroanatomist said:
> ...



Back in film days, switching lenses around the 70mm was very annoying, mostly when shooting portraits.
So I think with a cropcam one can be fine with 70mm, as it is 110mm.
I don´t know what your subjects are, but with a 70-200 lens also in your pocket, would you think 24-70 on crop is also good to manage?


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## slclick (Dec 19, 2016)

24-70 on a 1.6 was always awkward for me, the 70-200 was great. But what do I know, now the 50-100 is a hot item for crop bodies.


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## picturefan (Dec 19, 2016)

slclick said:


> 24-70 on a 1.6 was always awkward for me, the 70-200 was great. But what do I know, now the 50-100 is a hot item for crop bodies.



This lens would be pretty amazing, if it would be possible for FF also!
With ww-zoom, 50-100 and tele you would be ready for everything!


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## neuroanatomist (Dec 19, 2016)

slclick said:


> 24-70 on a 1.6 was always awkward for me, the 70-200 was great.



I found the 70-200 /2.8 to be 'awkward' on APS-C - often too long for indoor use (where the f/2.8 is useful), often too short for birds/wildlife (but I did have the 100-400 at the time). I found it most useful for outdoor event shooting. However, once I added a 5DII to my kit, the 70-200mm focal length became a lot more useful,


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## Act444 (Dec 19, 2016)

neuroanatomist said:


> slclick said:
> 
> 
> > 24-70 on a 1.6 was always awkward for me, the 70-200 was great.
> ...



I tend to agree to a certain extent - particularly indoors, 70mm proved to be too tight on crop for even mid-range shots. However, I did like the reach of 200mm particularly at signings which enabled me to sit farther back and be less of a "distraction". With FF I have to be in the first couple of rows to get similar coverage - that part I miss about crop, but in general with FF the 70-200 range makes more sense and is more useful for a greater variety of situations. 

And the 24-70 range made NO sense at all to me on crop sensor cameras. 24 not wide enough, 70 not long enough...24-105 at least had some reach, and I bought that lens originally to use with my T2i (although I still own the 24-105, this one's a different copy).


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## LesC (Dec 22, 2016)

I would think the 24-70 would be very nice on a crop sensor IQ-wise considering it's only using the middle portion of the lens, well, not the edges anyway. 

Really depends on what focal length you're happy with too - I'd find the 24 end not wide enough on a crop sensor - I used the 17-40 as my walkabout lens for several years on a crop sensor body (EFL of 27-64) but now use a 24-70 F2.8 on full-frame.


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## picturefan (Dec 23, 2016)

Sharlin said:


> Number of (mega)pixels being equal, a FF sensor has physically bigger pixels (photosites). This means that beyond a certain point, sensor resolution is a bottleneck and lens differences become less relevant. The smaller and denser pixels of a crop sensor demand more resolution from the lens as well, the lens becomes the bottleneck. The same holds for high-resolution FF cameras like the 5Ds which has pixel density roughly equal to that of the 7D2.



Could anybody guess which one -7DII or 24-70 4.0- would be the "bottleneck" in this combo, resolution-wise??
The sensor in this example is very demanding, but the lens, corresponding, offers high image quality.


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## neuroanatomist (Dec 23, 2016)

picturefan said:


> Could anybody guess which one -7DII or 24-70 4.0- would be the "bottleneck" in this combo, resolution-wise??
> The sensor in this example is very demanding, but the lens, corresponding, offers high image quality.



To what 'bottleneck' are you referring? Bottleneck suggests you're not getting what you'd expect. System resolution is a combination of the effects of multiple components, not just lens and sensor, but also the AA filter, the demosaicing algorithm used for the RAW images, etc.


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## gruhl28 (Dec 23, 2016)

The sharpness on a crop camera with smaller pixels is going to look worse than on a FF with a similar number of larger pixels, so it's no surprise that the lens (or any lens) doesn't look as good on the 7DII as on the 1Ds. But that doesn't explain why the 18-55 II would look sharper than the 24-70 f/4. I know the kit lens is supposed to be reasonably good optically, but I would not expect it to be better than the 24-70 f/4.


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## picturefan (Dec 23, 2016)

gruhl28 said:


> But that doesn't explain why the 18-55 II would look sharper than the 24-70 f/4. I know the kit lens is supposed to be reasonably good optically, but I would not expect it to be better than the 24-70 f/4.



Let's say it must be sample variation of the lens at the TDP test, as I also guess that 24-70 must look sharper than the kit-lens. That's the point. The kit-lens is quite good, but 24-70 should be even better. 
On all other cameras the 24-70 performs very good ("as expected") at TDP, but not so on 7DII. One of both must be the "bottleneck" (or sample variation). 

My real life experience is that 24-70 4.0 is a good performer on crop, on 7DII the lens is nearly close to the 24-70 2.8II, in terms of resolution. 
In no point I can proof the results of TDP with the combo 7DII and 24-70 4.0. I want to understand that (because in all other ways, I find TDP very useful and with reliable results). 
Of course, I can post it on TDP, maybe they can do another testing. 

But here I'm interested in user's opinions about that combo. Are you satisfied with resolution? Is someone doing portraiture or events with that combo?


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## AlanF (Dec 23, 2016)

picturefan said:


> All tests on tdp with 7DII and 24-70 4.0 are showing not really sharp results with that combo (even 18-55 II is sharper on 7DII than 24-70 4.0).
> Can anybody please explain why that is?
> Anybody got some experience with that combo?
> 
> Thanx.



TDP has not tested the 18-55 II on the 7D II - it's tested on the 30D only. The 18-55 STM has been tested on the 60D, where it is sharper than the 24-70. The 18-55 STM is a remarkably sharp little lens, getting a 4 star rating on Photozone - http://www.photozone.de/canon-eos/831-canon_1855_3556stmis

One of the great virtues of the Canon APS-C cameras is that there are excellent and cheap lightweight lenses designed by Canon for them (as well as Sigma and Tamron to some extent) and you don't have to lug around heavy lenses designed for FF.


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## neuroanatomist (Dec 23, 2016)

AlanF said:


> TDP has not tested the 18-55 II on the 7D II - it's tested on the 30D only.



In fact, they did. The EF-S 18-55mm f/3.5-5.6 IS II...but not the STM version. It does get a bit confusing with so many versions of that lens.


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## AlanF (Dec 23, 2016)

Oops! I got my first 18-55 with the 300D (the first Rebel) in 2003/2004, which set me on an expensive road.


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## Mt Spokane Photography (Dec 23, 2016)

AlanF said:


> Oops! I got my first 18-55 with the 300D (the first Rebel) in 2003/2004, which set me on an expensive road.



Pretty close to when I bought mine, I spotted a DPR announcement and picked one up at our local camera store. I was familiar with film SLR's and had a Nikon CP-990, so I expected that the rear LCD would have a live view, and was disappointed when it did not, since I used it for product photography and wanted to make sure of focus and composition as well as brightness before capturing the image.

When the 40D came out with Live View, I sold my 6 month old 30D and bought one. It paid for itself in time saved taking multiple shots until everything was how I wanted it.


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