Yeah, I read that too. I tried to reproduce it with an ISO-chart using a 5D2 but saw no degradation in quality. In fact it's so good on all apertures that it's difficult to tell them apart. I had to go up to f/16 before the IQ dropped (although still very good)
He did not however specify at what distance this problem is supposed to happen so I can't reproduce his test.
I was skeptical at first about trading up from my version 1 to the new version but after reading so many enthusiastic reviews and comments i decided to go for it....i sold my version 1 and a few other lenses i havent used enough and received the new lens today..i have had a chance to try it out a bit and one thing i can say for sure is it is sharper wide open than my version 1 was and is incredibly sharp and fast all the way through...canon keeps raising the prices on these new lenses but if they continue to produce such high quality lenses they will continue to sell the lenses at the higher prices...i am impressed thus far although with admittedly a small sample size
for what it is worth after reading the account of the guy having problems when he stops down I decided to test it out for myself because i had really done much of my test shots wide open which is how i normally test a lens...I stopped down to f 8 and took a bunch of test shots and my first reaction was..oh no,maybe there is indeed a problem...until i realized that i had forgotten to adjust my ISO from the 2.8 setting prior...as soon as I got the shutter speeds back up to workable levels everything was sharp as a tack and wonderful....perhaps that gentleman got a bum copy?
Sheldon N wrote:
Has anyone encountered this issue referenced by Lloyd Chambers? http://www.diglloyd.com/diglloyd/2010-03-blog.html#blog20100326Canon70_200
Apparently he is experiencing a decrease in IQ when stopping down past f/4, at certain focus distances, between 135-200mm.
Not sure of the exact details though...
I just used the-digital-picture shots to compare image quality at different focal lengths and aperture sizes. None of that image quality degradation.
I got the lens before 2 days and i can say that i am now thinking seriously about selling 135L even after selling 200f2.8LII and 70-200f4IS, however the 135L weight and compact make me hold, but maybe not for long.
I'm trying to read the Diglloyd site. But it seems like the review is only for subscribers. Bummer. I am not about to subscribe just to read this one article.
Anyone have more details on the tests run by Diglloyd?
For what it's worth, here are two center crops of a short test I did last week at 200mm.
At F8 it does look very slighter softer in parts (see the capitol building) but I didn't pay too much attention because the results were still acceptable. Too bad I didn't do a test at F4, and now I can't because I've sent my camera back to Canon for maintenance.
Apparently he is experiencing a decrease in IQ when stopping down past f/4, at certain focus distances, between 135-200mm.
Not sure of the exact details though...
It is almost impossible to discuss the decrease in IQ he's talking about, since the article is not publicly available.
As a reminder, nearly all quality optics peak in center performance at apertures around f/4. The "degradation" at f/11 due to diffraction is easily visible. It is easier to see on high pixel density bodies like the 7D, but also on current FF bodies:
DigLLoyd's subscription IMO is worth every penny you pay for it.
re the 70-200 it is amazing at 2.8 and better at f/4
no sign of the prob at 18ft
not yet tested at intermediate; 50 ft
but it is not diffraction
He does think it is a design flaw rather than a bad sample which is most disturbing, because in the long run we all need the top end competition to improve the breed and if his observations turn out to be well founded, it will be a disaster following on the probs some encountered with the 1D3.
I can honestly say his is one of the best learning sites I have come across and is well worth the money
Pony up the money, it is not just about this one lens. There is a wealth of carefully crafted information
At close focusing range DigLLoyd doesn't have a problem either. The problem appears in the center, starting already at 5.6 and getting progressively worse, at focusing distances of around 60 meters, if I remember correctly. F2.8 and F4 have no problems whatsoever. Also, you shouldn't be testing at MFD, there are no problems there.
Diglloyd is definitely worth the money, both for DAP and for Zeiss Guide.
I'm skeptical about the DigLLoyd results. Now I can understand if he reserved judgement and said that he would test another sample, but I think he is jumping to conclusions after testing one sample.
Anyway, test at 58 m (distance measured with a Leica DISTO D5), 200mm, 100% crops:
http://peltarion.eu/img/5D7D/digilloydiswrong.jpg
All shot raw and processed the same way in lightroom. Cropped and labeled in photoshop.
If you want to check the unprocessed RAWs yourself you can download them here (~170 MB zip file).
