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Archive 2010 · Decentered 70-200mm IS II

  
 
Ohmygod
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p.1 #1 · p.1 #1 · Decentered 70-200mm IS II


I tested my second copy today. My last one had similar issues and as dpreview found the same problem with their tested lens, it could be a widespread problem. I repeated the test three times to verify the result (100% crops of each corner):

http://img338.imageshack.us/img338/8594/screenshot20100510at625.jpg


I'd appreciate it very much if all owners of this lens who read this, could do a similar test. I used a fool-proof testing procedure that is very accurate:

1. Find an object that is far away (50m or more)
1. Mount camera on tripod
2. Set camera to fully manual, f/2.8, 200mm and two second timer & mirror lockup (if not in LiewView mode).
3. Focus the object using the middle focusing point
4. Turn off AF
5. Move the camera putting the object into each corner and fire.

The procedure is documented here on a german website: http://gletscherbruch.de/foto/test/dezentrierung/dezentrierung.html

This one goes back as well...






May 10, 2010 at 11:47 AM
jdben622
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p.1 #2 · p.1 #2 · Decentered 70-200mm IS II


Maybe I'm too stupid to understand this, but if you're focusing at the center, then recomposing without refocusing, won't you always be OOF due to the arc you've created with the center of the lens? And if that's not the case what would be the practical use of this technique?




May 10, 2010 at 11:58 AM
Ohmygod
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p.1 #3 · p.1 #3 · Decentered 70-200mm IS II


Not that it would even matter at this range, but each corner has the exact same distance to the object.
The purpose of this test is to see, if the lens is decentered. The satellite dish should be equally sharp in each corner (or unsharp for that matter).



May 10, 2010 at 12:09 PM
sangdabom73
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p.1 #4 · p.1 #4 · Decentered 70-200mm IS II


Or equally unsharp =P
Damn, ur fast!!



May 10, 2010 at 12:12 PM
mbailey
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p.1 #5 · p.1 #5 · Decentered 70-200mm IS II


jdben622 wrote:
Maybe I'm too stupid to understand this, but if you're focusing at the center, then recomposing without refocusing, won't you always be OOF due to the arc you've created with the center of the lens? And if that's not the case what would be the practical use of this technique?


As the OP said at that range the difference in distance with be more than covered by the DOF.

I see that its slightly decentered but I would contend its far from significant enough to make a difference in RW shooting.



May 10, 2010 at 12:15 PM
nazdravanul
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p.1 #6 · p.1 #6 · Decentered 70-200mm IS II


mbailey wrote:
As the OP said at that range the difference in distance with be more than covered by the DOF.

I see that its slightly decentered but I would contend its far from significant enough to make a difference in RW shooting.


You're just joking, right ?



May 10, 2010 at 12:19 PM
wickerprints
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p.1 #7 · p.1 #7 · Decentered 70-200mm IS II




That result is NOT insignificant. I would say that is VERY significant. It shouldn't do that at all. It's very clear that the lower left is much worse than the upper right.

We're talking about a $2500 lens. That kind of misalignment is not acceptable.



May 10, 2010 at 12:22 PM
mbailey
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p.1 #8 · p.1 #8 · Decentered 70-200mm IS II


nazdravanul wrote:
You're just joking, right ?


No Iam not joking. Rare for zoom lens to be perfectly centered at all potential focal lengths.



May 10, 2010 at 12:25 PM
Ohmygod
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p.1 #9 · p.1 #9 · Decentered 70-200mm IS II



No Iam not joking. Rare for zoom lens to be perfectly centered at all potential focal lengths.


I'm so afraid that this could be true. That's why I suggested, that everyone tests her/his lens to see if there are better ones out there. As you can imagine from the right hand corners, the lens is very sharp in the center. I was hoping that it'd would be possible to get this performance across the whole frame at such a price.


May 10, 2010 at 01:56 PM
SteveTuerk
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p.1 #10 · p.1 #10 · Decentered 70-200mm IS II


I'm looking at the wisp of foliage just to the right of (and presumably behind) the central brown dish antenna and I seem to see a degree of sharpness there that is quite different from what I see in comparing the images at the antenna atop the mast.

Is there an explanation for this, or am I seeing things which are not the case in fact?



May 10, 2010 at 03:28 PM
rd4tile
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p.1 #11 · p.1 #11 · Decentered 70-200mm IS II


I guess I'm not with it either, what's the difference between this test and taking a single shot at f2.8 of an object or scene all in the same plane and looking to see which corners are or aren't sharp. With every lens I've owned, including primes, there's usually a corner that's a bit less sharp then the rest. Some way less then others obviously, the point is if you've got a corner that's less sharp then the rest, send it back.


May 10, 2010 at 03:42 PM
Ohmygod
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p.1 #12 · p.1 #12 · Decentered 70-200mm IS II


The difference is simply, that you don't have to care much about being scientifically exact in your preparations, as almost everything you can do wrong in a test with a flat object at close distances, is being equalized by the range and the thereby given DOF. And I was at infinity here. I don't know how far away the dish is. I guess it's approximately 300 meters.

Come on, test yours rd4tile! Don't be scared!
I wanted to convince myself, that mine is OK, but after I shot the map on the wall with this second copy last week and saw the unsharp left side, I was afraid that perhaps it wasn't my testing procedure that was faulty, but that it could be the lens, AGAIN! I resorted from doing any more map testing anyway though, as I was fed up with the stress of testing. I missed the feeling of being adventurous and finally wanted to have fun with the lens!
But then the damn dpreview reviewed it and wrote this sentence:

"However it must be noted that our test sample clearly displayed some asymmetry in the optics at close focus distances, with the right side of the frame becoming visibly softer than the left - something which may not be representative of the design as a whole."


After I read that, I felt reminded of the first copy I had. And the problem certainly wouldn't go away if you get further away then a "close distance"! It becomes less apparent, because in most scenes we have objects at different distances, some of which would probably cover it all up. But in landscapes at infinity it becomes clear what is going on! Now some will say, that this is made for action and reportage and not for landscapes. This is partly true - at least we see first incarnation mostly being used in that context. But I don't think that shortcomings due to a defect introduced by sloppy QC and too little time spent into adjusting the product properly should limit the field of application. Even the cheapest Canon lens should be properly centered.

After all, it depends on how picky one is of course and how versatile you want the lens to be. If I wouldn't have noticed any irregularities after a normal RW shooting however, I would never have hung up a map or done a decentering test as well!
But it did show up in landscape pictures, where far away houses would be mush, while other houses at the same distance would be sharp. It showed up when I shot my wife in the grass and trees next to her.

This one is packed and makes it back to the store tomorrow. The shop is a good one though. I'll bring my 5D II as well and probably I can redo some tests there with a few more lenses. Might well be, that I'll take the one I have back home. Should it turn out to be true, that this is a systematic outcome of clumsy QC with all lenses performing equally bad.
Then it's time for Plan B.

Edited on May 10, 2010 at 06:21 PM · View previous versions



May 10, 2010 at 05:01 PM
retrofocus
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p.1 #13 · p.1 #13 · Decentered 70-200mm IS II


Yeps, looks like you have a severely decentered > $2K lens. Glad that I don't see such thing with my 70-200 f4 IS.. . I hope everything works out for you with the next copy! Good luck!


May 10, 2010 at 05:56 PM
Gochugogi
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p.1 #14 · p.1 #14 · Decentered 70-200mm IS II


If you print 8x10, 11x14 & 16x20 the corners won't matter. All my lenses are a little soft in one or more corners but once printed, matted and framed the corner is long gone. Even if you print full frame 8x12, 13x19, etc., the mat will cover the extreme corners so the worse of it will be out of sight.


May 10, 2010 at 06:07 PM
retrofocus
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p.1 #15 · p.1 #15 · Decentered 70-200mm IS II


Gochugogi wrote:
If you print 8x10, 11x14 & 16x20 the corners won't matter. All my lenses are a little soft in one or more corners but once printed, matted and framed the corner is long gone. Even if you print full frame 8x12, 13x19, etc., the mat will cover the extreme corners so the worse of it will be out of sight.


Hmmm, I see your point, but I would be very annoyed spending a fortune on a L lens update and seeing such poor corner performance. No way!



May 10, 2010 at 06:49 PM
Ernie Aubert
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p.1 #16 · p.1 #16 · Decentered 70-200mm IS II


Here's what I got with my 5DII, all at f2.8, tripod, MLU, remote release:

70mm, overall scene:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20overall%20scene.JPG
70mm, top left:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20top%20left.JPG
70mm, top right:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20top%20right.JPG
70mm, bottom left:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20bottom%20left.JPG
70mm, bottom right:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20bottom%20right.JPG
70mm, center:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/70mm%20center.JPG

200mm, overall scene:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20overall%20scene.JPG
200mm, top left:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20top%20left.JPG
200mm, top right:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20top%20right.JPG
200mm, bottom left:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20bottom%20left.JPG
200mm, bottom right:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20bottom%20right.JPG
200mm, center:
http://photos.imageevent.com/bhakti_rider/miscelaneousstuff/70200test/200mm%20center.JPG



May 10, 2010 at 06:54 PM
rd4tile
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p.1 #17 · p.1 #17 · Decentered 70-200mm IS II


Ohmygod wrote:
Come on, test yours rd4tile! Don't be scared!


I don't own a full frame (have MKIV) first of all and mine is razor sharp when and where it should be including all the corners so why would I waste time with a test like that?

Here was my tests:

Shoot a series of similar pics with the f4L IS I had at f4 and compare - result of test: f4L IS gone.

Shoot a series of similar pics with new 100 macro IS - result of test: 100 macro IS gone.

Shoot a series of similar pics with 400 f5.6L vs 70-200 with 2X - result of test: 400 5.6L gone.

Bag lighter by a number of lbs / wallet fuller with extra dollars.



May 10, 2010 at 11:07 PM
Ohmygod
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p.1 #18 · p.1 #18 · Decentered 70-200mm IS II


That looks the way it should look like Ernie. Nicely presented too, thanks alot!
So they did a decent job adjusting at least some of them properly.
Looks very convincing, but we need more to come!

rd4tile: So it really is as good as the 400 5.6L with the 2x extender? I tried it with mine once, but haven't actually made any real pictures with it.
And I agree. You should have noticed a difference if it would be decentered after having conducted so many comparisons.




May 11, 2010 at 02:50 AM
EA6B
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p.1 #19 · p.1 #19 · Decentered 70-200mm IS II


What do your clients say?


May 11, 2010 at 03:30 AM
thw2
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p.1 #20 · p.1 #20 · Decentered 70-200mm IS II


Perhaps one convincing way to test for decentered elements is to take a shot with the camera upright and another shot with it turned upside down. The blurred edge or corner should move accordingly. A simple brick wall will do nicely as subject..


May 11, 2010 at 03:50 AM
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