EF 24-70 f/2.8L Replacement [CR2]

ablearcher

EOS 80D
Sep 23, 2010
152
0
Canada
I might consider the new one for outdoor location shoots. However, at this point I prefer primes for low light and better background blur (and a better IQ in general). Also, 24-70 feels kinda short for studio work (I'm happy I went with 24-105L for that). But 24-70 will work well with 70-200 for weddings and location shoots on two bodies with good light...
 
J

Justin

Guest
I have to say I am tired of waiting for this lens. I sold my aps-c camera for a 5D2 almost a year ago and had to sell my 17-55 2.8 IS, my favorite lens. At the time I expected that a 24-70 was imminent. Anyone would who followed camera rumors for a few years. Sure I was excited when the 70-200 2.8 successor was launched. Yes I shoot with it all the time, but I find myself making compromises all the time too. I pack the 35 1.4 but only get a clean shot with very careful setup and at anything under 2.8 it's not tack sharp. I have a 24-105 but it leaves something to be desired due to narrow max aperture. Maybe the thing to do is go buy a 7D or a 60D and get the 17-55 back. I really miss this range. I don't want to be without an image stabilized zoom lens any longer. Come on Canon. Release this lens already.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Justin said:
I sold my aps-c camera for a 5D2 almost a year ago and had to sell my 17-55 2.8 IS, my favorite lens.
The 17-55/2.8 IS lens on APS-C @ iso 100 corresponds to 27-88/4.5 on FF @ iso 160 (same exposure, same depth of field, same photon noise), so if you were content with that lens I see no reason you would be less happy with 24-105/4L IS on 5d2.
 
J

Justin

Guest
I understand your point, but the qualities of these lenses are not equivalent. In terms of sharpness, I have to stop down to f11 on the 24-105 at 70mm to get even close to the 17-55 at the long end. So in other words, and to be fair because I didn't put it in my earlier comment, the wider maximum aperture is not he only thing I am looking for in a standard zoom lens. Yes I want 2.8, because as you suggest it produces very narrow DOF on a full frame camera. But I am looking for a sharp optic as well, in addition to contrasty, punchy, low CAs, minimal distortion, fast focusing output.

epsiloneri said:
Justin said:
I sold my aps-c camera for a 5D2 almost a year ago and had to sell my 17-55 2.8 IS, my favorite lens.
The 17-55/2.8 IS lens on APS-C @ iso 100 corresponds to 27-88/4.5 on FF @ iso 160 (same exposure, same depth of field, same photon noise), so if you were content with that lens I see no reason you would be less happy with 24-105/4L IS on 5d2.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Justin said:
In terms of sharpness, I have to stop down to f11 on the 24-105 at 70mm to get even close to the 17-55 at the long end.
That is surprising, I haven't seen complaints on the sharpness of the 24-105/4L IS before (most complaints are about the strong barrel distortion at 24mm). Perhaps you have a bad copy/AF problems? According to MTF measurements by photozone.de, the 24-105/4L on 5D2 should be slightly sharper than 17-55/2.8 on 50D (although the latter is better than 24-105/4L on 50D; this is because of the APS-C 1.6x center resolution disadvantage compared to FF). It also seems the 24-105/4L is at its worst in the corners at 70mm (but still better than 17-55/2.8 at 55mm).

But yes, I'm very fond of my 17-55/2.8 IS lens and, just as you, I'm waiting for a normal F/2.8 zoom with IS to switch to FF (e.g., 24-70/2.8L IS). Even with a good calibrated copy, merely doing "slightly better" is not big enough incentive for me to switch.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Just FYI Justin, I got access to exactly your setup (5D2+24-105/4L) and took the opportunity to compare it to my 7D+17-55/2.8. Tripod, no IS, with a boring bookshelf as the subject. Manual focusing of centre with live view, remote shutter release with mirror lock up. Focal plane parallel to bookshelf. 24-105/4L @ 70mm (supposedly its worst focal length), 17-55/2.8 @ 44mm (the equivalent). iso 160 and 1s exposure for 5D2, iso 100 and 1s exposure for 7D (gives the same exposure level).

Result: Sharpness about equal in corners, 24-105/4L better in centre.

Then I stepped down the aperture 2 steps (i.e. to 8.0 and 5.6, respectively) and increased exposure time to 4s.

Result: 24-105/4L@8.0 improved corners significantly, and center somewhat, clearly out-resolving the 17-55/2.8@5.6, which didn't improve as much compared to wide open.

Conclusion: The resolution of the 5D2+24-105/4L is no worse than 7D+17-55/2.8, so have no remorse for selling your EF-S lens.

(NB, I can't guarantee that my results are typical, maybe I received a good 24-105/4L copy and a poor 17-55/2.8, but what I find is in line with expectations from MTF measurements)

If you're interested I can find a way to post relevant crops of the images.
 

neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,601
2,058
epsiloneri said:
But yes, I'm very fond of my 17-55/2.8 IS lens and, just as you, I'm waiting for a normal F/2.8 zoom with IS to switch to FF (e.g., 24-70/2.8L IS).
I also really like my EF-S 17-55mm f/2.8 IS. But, keep in mind that with the difference between a 1.6x and FF sensor, the 24-105mm f/4L IS actually specs out better on FF than the 17-55mm on 1.6x crop. With the crop factor applied to aperture (as it does in terms of DoF for the same framing), the FF equivalent of the 17-55mm f/2.8 is 27-88mm f/4.5, so you can see that the 24-105mm f/4 on FF is 3mm wider, 17mm longer, and 1/3-stop faster. Granted, shutter speed is faster with f/2.8, but since the ISO performance is also improved by 1.33 stops on FF vs. crop, you can get equivalent noise performance and bump to a higher ISO on FF f/4 to maintain the shutter speed you'd have on crop at f/2.8.

So, bottom line, if you are waiting for a 24-70mm f/2.8L IS because you want a FF-equivalent of your 17-55mm IS, you can have that right now as the 24-105mm f/4L IS.
 
F

Flake

Guest
While the effective field of view on a crop camera may be the same as a longer lens on a 35mm, the focal length does not change and therefore neither does the aperture. A 17 - 55mm lens may give the same FOV as a 27 -88mm but it's still a 17 - 55mm and the relationship between the first element and the focal length remains unchanged as does the aperture.
 

Macadameane

EOS RP
Oct 5, 2010
207
0
Flake said:
While the effective field of view on a crop camera may be the same as a longer lens on a 35mm, the focal length does not change and therefore neither does the aperture. A 17 - 55mm lens may give the same FOV as a 27 -88mm but it's still a 17 - 55mm and the relationship between the first element and the focal length remains unchanged as does the aperture.
You are right, but a FF camera also utilizes more overall light and is more suited for low-light photography and video shooting. Depth of field also can become thinner on a full frame. I don't know the technicalities, though, does someone want to shed some light? It probably is a matter of pixel size and spacing rather than "light gathering".
 
F

Flake

Guest
DOF becomes less because in filling the frame for a portrait the magnification increases therefore lessening the DOF.

In terms of FF working better in lower light the issue is not as simple as some would have us believe, put simply bigger pixel sites. Unfortunately a larger site does not mean a larger sensitive area or pixel, and then there is the isolation of one pixel from the next which is the cause of some noise. It is possible to have a large sensor with a small number of MP which is worse in low light than a small one with a higher pixel density.

However if you imagine a light source with a constant brightness (white) a lens with a given aperture will project uniform brightness over all the sensor, hence there is no difference between a FF camera and a crop one.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
neuroanatomist said:
So, bottom line, if you are waiting for a 24-70mm f/2.8L IS because you want a FF-equivalent of your 17-55mm IS, you can have that right now as the 24-105mm f/4L IS.
You're right, and that was exactly my point :) Jason was complaining that his 24-105/4L wasn't as good on his 5D2 as his 17-55/2.8 had been on his 50D, and I was surprised, because I thought the 24-105/4L would be similar but slightly better, if anything. I then went on and tested a 17-55/2.8 on a 7D and a 24-105/4L on a 5D2, and found that the latter was indeed very similar, but slightly better performer (for my copies).

But the bottom line is that I do not find slightly better compelling enough to go FF. A good 24-70mm f/2.8L IS on the other hand would convert me in an instant.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Flake said:
While the effective field of view on a crop camera may be the same as a longer lens on a 35mm, the focal length does not change and therefore neither does the aperture. A 17 - 55mm lens may give the same FOV as a 27 -88mm but it's still a 17 - 55mm and the relationship between the first element and the focal length remains unchanged as does the aperture.
You're right, but what is your point? The focal length just gives the image scale. 50mm/2.8 on FF gives exactly the same field (solid angle) as 80mm/4.5 on 1.6x APS-C (barring lens distortion). The flux of incoming photons per solid angle will be the same. The DOF will be the same. If the detectors have the same number of pixels with the same sensitivity (say fraction of photons actually detected, also called quantum efficiency) and read-out noise, dark current etc, then the resulting image will be statistically identical in all respects.

The lens is just an optical system to capture photons and compress them to a small image. The advantage of FF sensors is not that they are inherently more sensitive. The advantage is that it's easier to make optics that produce larger image scales (e.g., it's easier to produce a good EF 80mm/1.2 lens than an EF-S 50mm/0.75 lens).
 
F

Flake

Guest
epsiloneri said:
[You're right, but what is your point? The focal length just gives the image scale. 50mm/2.8 on FF gives exactly the same field (solid angle) as 80mm/4.5 on 1.6x APS-C (barring lens distortion).

The point was in response to the previous post!
aperture does not affect FOV, as you appear to be quoting however, and f/2.8 is important on Canon cameras because of the more sensitive focus centre spot.

Perhaps you would explain the change in focal length in the wrong direction? 50mm on FF is the same FOV as a 30mm (nearest equivalent) on a 1.6 crop, the aperture values would not change, DOF might depending on conditions
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Flake said:
Perhaps you would explain the change in focal length in the wrong direction? 50mm on FF is the same FOV as a 30mm (nearest equivalent) on a 1.6 crop, the aperture values would not change, DOF might depending on conditions
I don't think I understand. Yes, 50mm on FF shows approximately the same field as 30mm on 1.6x APS-C. You didn't state the aperture values, so I don't know what you mean when you write that they don't change. In relation to what? Focal length and aperture (as in entrance pupil) are independent quantities, and the f-number is their ratio.

Let's put it this (trivial) way. 50mm/2.8 on 1.6x APS-C is exactly the same as 50mm/2.8 on FF, where only the central 1/1.6 = 62.5% (in linear dimension) of the frame is used.

With shorter focal length, you compress solid angle onto a smaller part of the detector; so with 31.25mm you compress the same field on the APS-C as the 50mm does on the FF. If we assume that the entrance pupil is the same, that is, the same number of photons per solid angle is captured for both lenses, then that implies that the photon density at the detector must be higher for the 30mm lens (because the same number of photons were compressed onto a 1.6^2 smaller area). That is, the f-number is sqrt(1.6^2) = 1.6 smaller.

I'm sorry if my explanations are confusing, I'm sure there is a good web page somewhere which explains things better.
 
F

Flake

Guest
Unfortunately that's not so epsiloneri, you're counting the crop factor twice.
the final element of a 50mm f2.8 is 18mm on a 30mm 11mm (rounded out), but the ratio between these two is 1.6 (surprise!). If you then make allowance for the crop in a further calculation you count it twicw which makes the result wrong.

f/2.8 is a constant regardless of the focal length if the lens is pointed at a uniform light source the light reaching the sensor should be constant across its surface. Therefore the size of the sensor is unimiportant, as is the crop factor. A slightly more meaningful figure would be to use the pixel density, but even then as sensors peform differently it's difficult to make the test accurate enough to make any sense.

A FF camera and a crop camera pointed at the uniform light source with say a 50mm & 30mm both at f/2.8 and the same ISO should return the same shutter speed for correct exposure.

Just to make it more complicated though, not all cameras share the same bayer matrix, they can be stronger or weaker, then there's the anti aliasing filter, and they're not all the same either, not the microlenses. It's very difficult to compare like with like.
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Flake said:
Unfortunately that's not so epsiloneri, you're counting the crop factor twice.
Thanks for your comment, but you're not being very clear. What is not so? Please be very precise and refer to the exact statement you don't agree with, otherwise I have no hope in following you.

So you don't agree that 50mm/2.8 on a FF is identical to 31.25mm/1.75 on 1.6 APS-C? Or is it something else?

Flake said:
Just to make it more complicated though, not all cameras share the same bayer matrix, they can be stronger or weaker, then there's the anti aliasing filter, and they're not all the same either, not the microlenses. It's very difficult to compare like with like.
Yes, there are other effects, but they are less significant by comparison ("second order corrections") and more about engineering than fundamental physics.
 
F

Flake

Guest
So you don't agree that 50mm/2.8 on a FF is identical to 31.25mm/1.75 on 1.6 APS-C? Or is it something else?

Yes I don't agree with that, f/2.8 is f/2.8 regardless of the crop factor
 

epsiloneri

EOS 7D MK II
Aug 26, 2010
422
4
Flake said:
So you don't agree that 50mm/2.8 on a FF is identical to 31.25mm/1.75 on 1.6 APS-C? Or is it something else?

Yes I don't agree with that, f/2.8 is f/2.8 regardless of the crop factor
Ok, good, then I understand. You are right, that for the same lens the aperture doesn't change when you go from FF to crop. That would be weird. But now think of two different lenses that both share the same entrance pupil - say 18mm in both cases - but where the focal length is different, namely 50mm in one case and 31.25mm in the other. Then the image on a FF with the 50mm lens would be identical to the image of the 31.25mm on the 1.6x APS-C. And, also note, since the entrance pupil is the same, the f/#-number changes: 50/18 = 2.8 while 30/18 = 1.75. Which is what I stated in the quote above.
 

neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,601
2,058
Flake said:
While the effective field of view on a crop camera may be the same as a longer lens on a 35mm, the focal length does not change and therefore neither does the aperture. A 17 - 55mm lens may give the same FOV as a 27 -88mm but it's still a 17 - 55mm and the relationship between the first element and the focal length remains unchanged as does the aperture.
True. But not really the point I am making... 55mm on a crop body is equivalent to 88mm on FF, and f/2.8 is f/2.8 regardless. But for the same framing, you'd be closer to the subject with a FF body, meaning shallower DoF. It also means the perspective is different, so it's not really the same shot. But from a technical standpoint, on FF DoF is effectively shallower, and when comparing current FF sensors to current crop sensors, ISO performance is improved so one can increase ISO by a stop to 'make up the difference' between f/2.8 and f/4 (in terms of shutter speed) with no noise penalty.

What that means, and my main point, is that functionally the 24-105mm f/4 on FF is approximately equivalent to the 17-55mm f/2.8 on a crop body (from a DoF and exposure standpoint, plus it has a broader focal range). So the "I'm not going FF yet because there's no FF equivalent to the 17-55mm f/2.8 IS" argument is a fallacy, since on FF, f/4 + better ISO performance is comparable to 1.6x f/2.8, and both lenses have IS.

Now, if someone is waiting for f/2.8 IS on FF because the whole point of moving to FF is to achieve better performance, rather than comparable performance (from a technical standpoint), I can't argue with that - so, if that's the case, keep on waiting for the 24-70mm f/2.8L IS.
 
F

Flake

Guest
One of the problems is that f/2.8 is a magic number for Canon cameras and gives a brighter viewfinder, and more accurate autofocus.
The current f/2.8 24 -70mm is a far better lens than the 24 - 105mm f/4 IS and I'm speaking from experience owning both of them, just sold the f/2.8 in anticipation of a new one before values fall.
Photozones test of the 24 - 105mm f/4 IS on FF wasn't what I wanted to see, it has problems with edge softness vignetting, distortion, and its minimum focus distance and magnification leave a lot to be desired. It's useless for close up work, the 17 - 55mm is much closer to the 24 - 70mm here.
The saving grace of the 24 - 105mm is the IS which the 24 - 70mm doesn't have, when it finally gets it I think the 24 - 105mm will be going on Ebay!