Testing sharpness of new 24-70 F2.8L

[TJJ]

Just bought myself a brand new 24-70 (with 2010 date code) but I'm not taken by the image quality which is strange given that so many people seem impressed with their lenses.

Does anyone know if there's a way to test the lens for IQ?

I have a couple of images taken at F2.8 and F22 on a tripod but I've got better results from my 18-55 kit lens.

Any thoughts?

Thanks

Trevor

 

[scottthehat]

post some pics.

 

[TJJ]

On both images the focus point was the top corner of the A3 clip frames on the floor
Resized down to 800 pixels for the forum. No PP done.

F2.8

F22

What do you think?

 

[Chris Primadona]

Its a tricky photo to really check out sharpness. Do you notice a difference when manually focussing? Maybe try one with auto and one with manual then post a 100% crop?

 

[Dogfish_magnet]

The shutter speeds to slow for anything meaningful - F22 will be soft due to diffraction and the lens wont be at its sharpest at f2.8 either. I went from a Tamron 28-75mm to the 24-70mm and there wasn't a lot (if any) difference of center sharpness , but the canon was better on the outer edges - and the focus is a lot quicker

 

[scottthehat]

you need to take of a pic of a flat item with detail like a 20 note or somethng simular.

 

[HoppyUK]

We can't tell anything from those images. If you want to know how good it is, shoot identical images side by side with a lens of known quality, such as your 50 1.8, and compare. Shots in isolation can be skewed by so many things they're almost meaningless.

BTW, my Exif reader says those pictures were taken with a Canon 135 2.8 SF lens! At 24mm...

 

[TJJ]

I downloaded and laminated the test sheet from here
http://www.photo.net/learn/focustest/scale45.jpg

1 50mm F1.8 Mk2 at F2.8

2 24-70 F2.8L at F2.8 and 50mm

Any thoughts? I accept that a prime should be better but a nifty fifty over a 24-70L?

 

[Chris Primadona]

I would say my 24-70 is slightly sharper than my fifty (but only after 2.8). Is there any way you could try another 24-70 to see if theres a marked difference? It actually looks reasonable to me considering you are comparing to a stepped down prime.

 

[HoppyUK]

That's a focus test target (and not a very good one at that).

If you're looking to check sharpness, just shoot a regular subject with the two lenses and blow up sections with a bit of detail to 100%.

What makes you think it's soft?

 

[scottthehat]

as richard has said not the best subject, but also remember the prime has been stopped down and should be sharper the 27-70mm is wide open, to me from those pics the focus is spot on and i would be happy with that.
also the 50mm is back focusing on the chart.