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Author Topic: Problem Lens Canon 17-40 mm f4, similar experience?  (Read 4195 times)
WilliamF
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« on: November 10, 2008, 09:29:39 PM »
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After buying a wide format printer I see my 17-40 mm L f4 can only make enlargements up to about 11.5*8 or 16*11 at the long end. It is somewhat soft, even at f8. My 70-200 mm f4 IS produces superb prints up to 16*24 on my 20D.  My main interest is landscape for wide angle.  I called Canon who told me it is soft at the wide end, not what I expected for an L lens.

Is it worth having them examine the lens?  The MTF chart is not so different from the 35 mm f1.4 L . Has anyone had a similar experience? Any suggestions for a replacement?

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250swb
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« Reply #1 on: November 11, 2008, 10:15:59 AM »
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My 17-40mm was soft as well. I think it is a 'characteristic' of the lens.

Steve
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Geoff Wittig
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« Reply #2 on: November 11, 2008, 02:59:47 PM »
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Quote from: 250swb
My 17-40mm was soft as well. I think it is a 'characteristic' of the lens.

Steve

I wouldn't agree with that. First, there's the issue of wide angle zooms in general. True, they're not as sharp in terms of absolute lines per millimeter resolution as Canon's 70-200 f:4 or f:2.8 L zooms, which really are exceptionally good. But they're not that bad. Then there's the matter of scale; a wide angle zoom photo of a landscape with trees will render individual trees so small on the sensor that you're hitting physical resolution limits, while a focal length of 100 mm is more forgiving. Then there's the diffraction problem; as I understand it, diffraction will harm apparent sharpness more at f:16 with an 18 mm focal length than it will at 100 mm, though I could be wrong.

Canon's 17 40 mm L zoom is actually rather highly regarded for sharpness, particularly at apertures like f:8 or so, within the limits imposed by optical reality. It won't compare to a Zeiss 18 mm prime, but it's not "soft". I have the older 16 35 mm f:2.8 L zoom, and it's...well, not that bad on a full frame camera like the Eos-1Ds III. Used with meticulous technique on a tripod at an aperture like f:8 (stopped down enough to limit aberrations, not enough to hit the diffraction wall), images are pretty darned sharp centrally. Corners tend to show some color fringing (especially if back-lit) and softness, but I've printed some images up to 20x30" and they're pretty good. Used hand-held at wide open apertures, then sure, it'll get pretty soft.
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Paul Sumi
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« Reply #3 on: November 12, 2008, 12:17:15 AM »
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With which camera body are you using this lens?  Keep in mind that the 17-40 came out as Canon's first "for digital" zoom lens way back when the 6 megapixel EOS 10D was introduced with its 1.6x crop.  I'm pretty sure the lens was optimized for crop frame cameras -- but not today's high resolutions or full frame use.

That said, the 10D-with-17-40 combination worked very well for me and continues to work well with my 1D Mk2.  It's "okay" in the corners on my 1Ds Mk2 stopped down to f/8 or f/11.  This last is just a feeling as I have not tested this empirically, and naturally YMMV.

Best,

Paul
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WilliamF
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« Reply #4 on: November 12, 2008, 07:54:23 AM »
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Quote from: PaulS
With which camera body are you using this lens?  Keep in mind that the 17-40 came out as Canon's first "for digital" zoom lens way back when the 6 megapixel EOS 10D was introduced with its 1.6x crop.  I'm pretty sure the lens was optimized for crop frame cameras -- but not today's high resolutions or full frame use.

That said, the 10D-with-17-40 combination worked very well for me and continues to work well with my 1D Mk2.  It's "okay" in the corners on my 1Ds Mk2 stopped down to f/8 or f/11.  This last is just a feeling as I have not tested this empirically, and naturally YMMV.

Best,

Paul

I am using a 20D 8.2 Mpix Canon crop camera. Results center frame using a tripod & mirror lock up are really poor in a landscape setting. As I am intending to upgrade to a full frame sensor one day I may as well change it to a prime 24 mm or 35 mm. I do wonder if its worth the money to have Canon service the lens.
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Paul Sumi
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« Reply #5 on: November 12, 2008, 09:20:29 AM »
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Quote from: WilliamF
I am using a 20D 8.2 Mpix Canon crop camera. Results center frame using a tripod & mirror lock up are really poor in a landscape setting. As I am intending to upgrade to a full frame sensor one day I may as well change it to a prime 24 mm or 35 mm. I do wonder if its worth the money to have Canon service the lens.

It's probably worth having Canon service the lens, but I would also recommend that you also take in your camera body to make sure both are within focusing tolerances.

Paul
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spotmeter
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« Reply #6 on: November 13, 2008, 09:19:50 PM »
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Quote from: WilliamF
After buying a wide format printer I see my 17-40 mm L f4 can only make enlargements up to about 11.5*8 or 16*11 at the long end. It is somewhat soft, even at f8. My 70-200 mm f4 IS produces superb prints up to 16*24 on my 20D.  My main interest is landscape for wide angle.  I called Canon who told me it is soft at the wide end, not what I expected for an L lens.

Is it worth having them examine the lens?  The MTF chart is not so different from the 35 mm f1.4 L . Has anyone had a similar experience? Any suggestions for a replacement?

I print 40 x 60 from my 17-40 on a 5D and they are tack sharp. So is my 70-200. But I think I was lucky in getting great copies of both lenses. In fact, I am surprised just how sharp they are, considering they are zooms.

I have tested them against Zeiss ZF primes, and the primes are only marginally sharper.

I would send your lens to Canon (along with your camera) to have it checked. Enclose photos showing the problem, especially if you have photos of the same subject taken with a prime to show the difference.  They may or may not help. I sent them a 24mm TS-E that was soft, and they said it was within specs. But yours sounds like it should be better than it is.
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reissme
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« Reply #7 on: November 14, 2008, 01:51:34 PM »
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Quote from: spotmeter
I print 40 x 60 from my 17-40 on a 5D and they are tack sharp. So is my 70-200. But I think I was lucky in getting great copies of both lenses. In fact, I am surprised just how sharp they are, considering they are zooms.

I have tested them against Zeiss ZF primes, and the primes are only marginally sharper.

I would send your lens to Canon (along with your camera) to have it checked. Enclose photos showing the problem, especially if you have photos of the same subject taken with a prime to show the difference.  They may or may not help. I sent them a 24mm TS-E that was soft, and they said it was within specs. But yours sounds like it should be better than it is.
I have the 17-40 f:4 , 70-200 f:2.8, and 28-70 f:2.8, all of them are very sharp to the edges on my 1DS Mark III. my 24-105 f:4 is not so sharp at the edges when wide open. I think my 17-40 is a superb copy of this lens.
Menachem Reiss
 www.reiss.co.il
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