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Old Mar 29, 2004, 12:38 AM   #1
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Default 70-200 owners, how does yours do wide open?

I don't think my 70-200 F2.8 IS does well at all wide open (F2.8), especially at 200mm. It is pretty soft. It gets better at shorter focal lenghts, but still soft. But then when I stop it down to F3.5 the quality dramatically increases. Here are two 100% crops at 200mm. First one at F2.8 1/4000, the second at F3.5 also 1/4000.

I'm interested in how well yours performs open? The question goes for all three models of the 70-200.

Thanks!
Barthold

PS This F2.8 shot is repeatable, thus its not a focus issue.



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Old Mar 29, 2004, 8:29 AM   #2
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I haven't noticed any issues with mine, but then again I don't specifically shoot wide open very often either.

That definately is a dramatic difference. Might be worthwhile to have it looked at and adjusted by Canon.
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Old Mar 29, 2004, 8:01 PM   #3
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My 70-200 F4 is a bit soft wide open at but so is my 100mm F2. That's one of the reasons I sent my camera back for calibration tests (with all of my canon lenses). It should be back in about a month. Then I'll know better what the deal really is.

I wouldn't be surprised if that's just the way it is, since I've read in many places and heard in the forum here that the sweet spot on a lens is hardly ever wide open but stopped down some, some as much as 2 or more full stops. I guess that means that the benefit of having F2.8 or less is that one finds the sweet spot 2 or more stops down still, but the sweet spot is a more open aperture setting.

I'm a bit surprised, though, at how much more contrast can be seen in your stopped down shot as well as sharpness. But I guess both go together somewhat.
I'm glad you posted this question and look forward to reading the responses you get.
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Old Mar 29, 2004, 8:55 PM   #4
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FYI

Something round as well: http://www.pbase.com/nhl/back_focus_tests :lol: :lol: :lol:

IMO you may want to shoot at a flat brick wall or newspaper or something...
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Old Mar 29, 2004, 9:42 PM   #5
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That is quite the dramatic difference.
Norm, love that new avatar!! :lol:
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Old Mar 29, 2004, 10:08 PM   #6
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Thanks Gandalf, that's the new SOBIG 08-3200mm f 0.5 LLL EX DO ISM with 14X BO converter.

PS - be careful Gandalf because I change my avitar regularly and statements like that can become somewhat outdated or misinterpreted. Kinda comical though when I came across it after I'd changed my "Bigma"avitar back to my own mug.
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Old Mar 29, 2004, 11:12 PM   #7
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Yes, I know that all lenses are a bit softer wide open. I'm just wondering if this is normal, between wide open and half a stop (!) stopped down.

It gets annoying to me when I add my 1.4x TC to my 70-200. At F4 the pictures are not acceptable anymore. I guess the TC just magnifies the softness.

Come on people, post your wide open and stopped down pictures. I'm curious to see how someone else's lens does! Maybe I should have mine looked at by Canon.

NHL, yours does well wide open! Is it front-focus though?

Barthold
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Old Mar 30, 2004, 12:01 AM   #8
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Barthold...

I hope that a few take you up on your above request and post a few photos like yours. Whether the subject is flat or round something seems definitely amiss in those two photos of yours and, as you say, the difference shouldn't be so radical at less than one stop difference. I just got through reading 34 reviews on that lens and only "one" hinted at a degree of softness wide open. Virtually every other reviewer claimed "tack sharpness" across the board, in every setting. Those two shots of yours just seem a bit too radically different and apparently you did similar tests with the same result.

I'd post some photos from my F4 but my camera is on it's way to Canon for testing at the moment and you probably want test shots from a 2.8 anyway. I hope a few take you up on your request. I don't blame you for being slightly frustrated and concerned. That lens costs a pile of money, which is fine if it produces the desired effect.
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Old Mar 30, 2004, 5:30 AM   #9
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Quote:
Originally Posted by barthold
NHL, yours does well wide open! Is it front-focus though?
I did this test to verify the front/back focus realizing the AF area is larger than its indicator in the viewfinder... and you did rigthly observe the camera is picking the left bottle rather than the right as in the other 3 shots in this series.

One thing to notice though: the DOF is paper thin at f/2.8, ie less than the coverage of the concave label which is only 1/4 of the thickness of the bottle. What this means is if you're not spot on, the picture will be soft: there's absolutely no room for front/back focus error here!

BTW Anyone noticed the shutter speeds at f/11 and f/22? 1/15s and 1/4s respectively at 200mm... :P



I really enjoy the f/2.8 for its Bokeh, here's another example of wide open:

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Old Mar 30, 2004, 8:39 AM   #10
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Hi Norm,

Thanks for looking at those reviews, saves me the trouble of doing the same :-) It sounds that my lens is abnormally soft wide-open, which is not a real surprise. I would expect it to do better for a L lens. Are you saying the F3.5 picture is also below expectations?

NHL, nice picture! Any sharpening applied?

Thanks,
Barthold
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