24-70mm softer than 35-70mm at 70mm?

[odagled]

Has anyone noticed that their 24-70mm is soft at 70mm? I bring this up because I noticed that my GF's 35-70mm is sharper @ 70mm than my 24-70mm both at f/2.8. I had the lens repaired in March but only noticed this recently. I will have another 24-70mm to compare in a week. Until then, anyone have experience with these 2 lenses?

 

[Braineack]

I can't find an MTF for the 35-70mm, but frankly I'm not that surprised.


edit: okay here --

this is the MTF for the 35-70mm as found on photographylife.com

@70mm

and here's the 24-70:

on paper, the 24-70 is MUCH sharper -- especially on the edges of a FF.

again, on paper, the 35-70 is only sharper at 70mm and f/2.8 at the very dead center.

 

[table1349]

Keep in mind, just because you have a fast lens doesn't mean you have to shoot it wide open. Stop down to say 5.6 on both and see what happens.

 

[adamhiram]

This is often the case with normal zoom lenses when shot wide open. I use a Nikon 17-55 on DX, and at 55mm at f/2.8, the image gets a bit soft. Stepped down 1-2 stops it sharpens right up. The same is true of the 24-70 - as sharp as it is, it can get a bit soft on the long end when shot at f/2.8. Try stepping it down to f/4 or f/5.6 at 70mm and see if you notice the same sharpness.

 

[odagled]

Of course. However, sometime I do need that 2.8 when I'm shooting an event with no flash allowed. I just figured that since it is a way newer lens, it would be sharper (or at least as sharp) as the older model where I need it most.