Another question about 100-400 L

I searched over the forum and read many reviews about this lens. But I have found diffrent reviews about it. Some reviews complainted about it's softness (like PhotoZone.de and photodo.com) and some reviews said that this lens is tack sharp (the-digital-picture.)

check out this link:
http://www.the-digital-picture.com …omp=9&FLIComp=0​&APIComp=4

in the above page, 400 f/2.8L at f/8 is only slightly better that 100-400L at f/5.6!!! I can't believe this!!

now take a look at this site:
http://www.photodo.com​/topic_74.html (results seems too soft!!)

A few month ago I bought Sigma 100-300. but I think I got BAD COPY!! now I want to trade 100-300 for Canon 100-400.

And another question: I know this lens is a big dust sucker. but how much this problem is serious?? I live in IRAN and here is no authorized canon service center. So I can't send the lens to cleen periodicaly.

Thanks for your answer.

my lens is 7 years old and has no dust issues.....

https://photography-on-the.net/forum/showthre​ad.php?t=295056

OK. I bought the 100-400 today. As th first impression I have to say that It'g great and really sharp. very sharp. Focus speed is not as fast as Sigma 100-300 or Canon 70-200 2.8, but it's reasonably ok.
Fortunatley I got a good copy.

Thanks again for your reply.

Daruosha wrote in post #2932572
OK. I bought the 100-400 today. As th first impression I have to say that It'g great and really sharp. very sharp. Focus speed is not as fast as Sigma 100-300 or Canon 70-200 2.8, but it's reasonably ok.
Fortunatley I got a good copy.

Thanks again for your reply.

Congrats... You're gonna love it.