Below is a MTF Chart comparison between Canon's 4 offerings in the 24-70 range.
In this order: Canon 24-70mm f/2.8L, Canon 24-70mm f/2.8L II, Canon 24-70mm f/4L IS and Canon 24-105 f/4L IS.
Any theoretical conclusions can be drawn from these charts?

2.8 II > 24-70 IS > 24-105

Fred Miranda wrote:
Any theoretical conclusions can be drawn from these charts?

Wide open (f4), the 24-70/4L has a comparable performance to the 24-70/2.8L II wide open (f2.8).
This is more of a testament of how good the 24-70/2.8L II is.
Still, the MTFs indicate that the 24-70/4L will be very sharp wide open - all the way to the corners.

Stopped down (f8), the 24-70/4L is actually sharper than the 24-70/2.8L II at 70mm.
Both are the same at 24mm.

Note, though, that the MTFs say nothing about distortion.

EDIT: fixing my previous post, as I was looking at the wrong charts.

It's a little confusing because the 24-70mm f/2.8L II has the 'wide' and 'tele' charts in reverse.

Can we compare it also to the 24-70/2.8 vers I MTF charts?

http://www.northlight-images.co.uk/cameras/lenses/ef_24-70_f28l_is.html

Fred Miranda wrote:
It's a little confusing because the 24-70mm f/2.8L II has the 'wide' and 'tele' charts in reverse.

It looks like both the 24-70's have similar optical performance wide open, which should mean the f/2.8 II will be even better at f/4.

Zero reason Canon can't update the 24-105 to have same performance as the new lens.

Fred Miranda wrote:
It's a little confusing because the 24-70mm f/2.8L II has the 'wide' and 'tele' charts in reverse.

Oops, I did not realize that.

So, stopped down (f8), both lenses are the same at 24mm.
At 70mm, the 24-70/4L is sharper.

Pixel Perfect wrote:
Zero reason Canon can't update the 24-105 to have same performance as the new lens.

... and charge $2000+ for it .

jorkata wrote:
Pixel Perfect wrote:
Zero reason Canon can't update the 24-105 to have same performance as the new lens.

... and charge $2000+ for it .

Well if it doesn't have the useless gimmick macro mode and HIS it probably be the same price. Still far more useful to me than the 24-70, which is too small a range for my liking for an f/4.

retrofocus wrote:
Can we compare it also to the 24-70/2.8 vers I MTF charts?

I fixed the wide-tele issues with some of the charts and added the 24-70mm f/2.8L IS (Mk1) to the mix...

jorkata wrote:
So, stopped down (f8), both lenses are the same at 24mm.
At 70mm, the 24-70/4L is sharper.

I agree that at 70mm, the new 24-70mm f/4L IS has a small edge at f/8 in the corners (resolution and contrast) but at 24mm, the 24-70mm f/2.8 II wide-open and stopped down has the resolution and contrast edge in the corner area.
According to these graphs, the two new Canon zooms are indeed exceptional and set themselves apart from both 24-70mm f/2.8L Mk1 and 24-105mm f/4L IS.

Fred Miranda wrote:
According to these graphs, the two new Canon zooms are indeed exceptional and set themselves apart from both 24-70mm f/2.8L Mk1 and 24-105mm f/4L IS.

Agree.

What remains to be seen, though, is the distortion of the new 24-70/4L - especially at 24mm.
The 24-105/4L has a really pronounced barrel distortion at 24mm.
Hopefully the new lens will be more like the 24-70/2.8L II than the 24-105/4L.

The differences show among these lenses are unlikely to make a visible difference in even a rather large print. Just sayin'... :-)

gdanmitchell wrote:
The differences show among these lenses are unlikely to make a visible difference in even a rather large print. Just sayin'... :-)

I think it will be quite visible in the corners and edges.

Plus we should get the improved AF performance on the new bodies that Roger has documented. That is a real plus.

I have a set of both 4.0 and 2.8 zooms. This looks like a nice fit, once the early adoption price comes down after 3-4 months.

I will probably go 17-40, 24-70, 70-200 4.0 and 24-70 II and 70-200 II 2.8 as my only lenses.

Plus the 40 & 18-135 STM for video on the T4i.

Canon has done well with all of their recent lenses. Very happy!

Cheers, Michael

mmurph wrote:
Plus we should get the improved AF performance on the new bodies that Roger has documented. That is a real plus.
Cheers, Michael

Indeed.

I shall wait for the ancient 17-40 f/4L lens to be replaced. The replacement will then join the 24-70 f/4L IS and 70-200 f/4L IS as my trinity of high quality f/4 zooms. The 50 f/1.4 will stay as my only fast prime lens. Maybe I will get the 35 f/2 IS; still undecided on that one. All these will be used on the 6D.

Replacement 17-40L will no doubt be dearer than 16-35L II especially if they add IS. Maybe they will make it 17-24 f/4L IS, so you don't waste glass for unnecessary overlap with 24-70.

17-24 + 24-70 + 70-200 + 200-400

Perfect travel kit

Appears to me the two newer lenses are going to be better in the edges and corners on a full frame.

I wish we had 70mm charts for the 24-105, though. My impression is it's better there than at the complete tele end and I think that will be an important point for a lot of people considering 24-105 vs 24-70 f/4 IS.

RCicala wrote:
Appears to me the two newer lenses are going to be better in the edges and corners on a full frame.
I wish we had 70mm charts for the 24-105, though. My impression is it's better there than at the complete tele end and I think that will be an important point for a lot of people considering 24-105 vs 24-70 f/4 IS.

Photozone's copy shows the 24-105 is particularly weak at 70mm:

"The EF 24-105mm L produced decent resolution figures in the MTF lab. At the wide end of the zoom range the center performance can reach very good to excellent levels followed by very good borders and good to very good extreme corners. Unfortunately the situation isn't quite as impressive at 70mm - the center performance remains very high but the border quality is soft at max. aperture so it's better to stop down to f/5.6 or preferably f/8 if you need a more even quality distribution across the frame. At 105mm the border quality recovers at max. aperture although it does still improve somewhat at medium aperture settings. The lens suffered a bit from field curvature and the lens alignment (centering) wasn't perfect at the long end of the range (still within test specifications)."

Pixel Perfect wrote:
Replacement 17-40L will no doubt be dearer than 16-35L II especially if they add IS. Maybe they will make it 17-24 f/4L IS, so you don't waste glass for unnecessary overlap with 24-70.

17-24 + 24-70 + 70-200 + 200-400

Perfect travel kit

Would that be the as-yet unannounced 200-400/5.6L IS ?

Pixel Perfect wrote:
Maybe they will make it 17-24 f/4L IS, so you don't waste glass for unnecessary overlap with 24-70.

Do you actually own a 17-40? There's a reason that one and the 16-35 extend past the ultrawide focals. It makes them useful. Overlap is not a bad thing.