Image sharpness on 17-40 F/4 L lens

[Gee Man]

Hello, I'm new to this forum, and this is my first post, so please let me know if there's one similar to this on here.


I recently purchased a 17-40 F/4 L lens, but am not entirely happy with the image sharpness. I've tried it from the widest to narrowest aperture, on a tripod and it's nothing compared to the 70-200 F/4 L lens I also have. I did try it last night, on a tripod, set at 40mm taking farily close-up portrait shots. This did yield some impressive picturs I might add, but I'm not that satisfied with the other shots I've taken.


Any suggestions people? Am I doing something wrong? Your advice would be greatly appreciated.


Cheers, G.

[alexniedra]

You very well could have a soft copy. As to what you can do to get another one - I hope someone with more buying experience could help you. I haven't bought any new lenses in a while.


Hope everything goes well.

[EdN]

I have a 17-40 F4 L and it is extremely sharp, better than my 24-105 F4 L IS. I agree that you may have a soft copy but I don't know what you can do about it.

[Gee Man]

Thanks for the input guys.


I feared I may have soft copy. I only recieved it on Friday, from a seller on ebay. He does have a website, so I'll see if he'll exchange it for me. Fingers crossed he will.


I'll keep you updated.


Thanks, G.

[Daniel Browning]

What body are you using it on?

it's nothing compared to the 70-200 F/4 L lens I also have.

The 70-200 f/4 L is certainly sharper than the 17-40. That's no surprise. On a crop body, there are plenty of lenses that are sharper than the 17-40:

• The $100 Kit lens is slightly sharper
• The $150 IS kit lens is much sharper
  
• $350 Sigma 18-50 f/2.8 is sharper.
  
  
• $450 Tamron 17-50 f/2.8 eats the 17-40 for breakfast.
• $1000 Canon 17-55 f/2.8 beats it, no surprise.

Yes, even the lowly $100 kit lens is sharper than the 17-40.


None of this is surprise given the fact that the 17-40 is a super wide angle lens for full frame. It compares pretty well against other full frame super wide angle lenses. But on a crop camera a higher standard of optical performance is required.

[Gee Man]

Hi Daniel,


Yes, I'm using it on a 400D.I was under the impression it would still perform (reasonably) well on a crop body?


Cheers

[Daniel Browning]

I was under the impression it would still perform (reasonably) well on a crop body?

For many photographers, the performance is more than adequate. The sharpness limitations of this lens would be difficult to notice at 8x10 and smaller print sizes, so it's correct to say that it will perform reasonably well.


It could be that your body is not able to achieve critical autofocus. Wide focal lengths show calibration errors more readily. Even if you miss focus just slightly it can make the lens look much worse than it actually is, so I would suggest checking that first. Filters, too, can reduce sharpness, especially on a wider lens. Make sure that any filters are removed.


It's also possible that your copy is even worse than most.


But even if you get a good copy and achieve critical focus, it will still not be quite as sharp as the 70-200 or or 17-50 and 18-50 lenses.

[Gee Man]

I took a few shots of my backgarden at f/16, and zoomed in 100% (!). You could say I'm picky (I am!), but I wasn't entirely satisfied with the results. I may be being a bit hasty here, as I mentioned in my original post, I took some colse up portrait shots at 40mm, and these are very sharp. The lens seems to be at it's worst at the wide end. But this was to be expected.


I'll persevere, and get back to the seller if necessary.


Many thanks for the information Daniel.


Cheers.

[Bob]

Can you show a photo that you are unhappy with?





On a tripod - IS off, Mirror lock-up on, shutter speed?

[Daniel Browning]

I took a few shots of my backgarden at f/16, and zoomed in 100% (!). You could say I'm picky (I am!), but I wasn't entirely satisfied with the results.

At f/16 the softness of the results were entirely due to diffraction. My comments were with regard to the performance at f/4.

The lens seems to be at it's worst at the wide end.

Agreed.