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Author Topic: Canon 70-200mml 2.8  (Read 2144 times)
NielsenPhoto
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« on: November 15, 2005, 10:50:30 AM »
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I am curious if anyone has seen the aforementioned lens have any issues in the left hand side at a fairly wide aperature.  I tend to push my equipment in terms of my expectations.  It is tack sharp every where else at this aperature.  I have actually seen this on most every Canon Lense.  Am I asking too much from the Canon Lenses.

For knowledge/reference sake I shoot a 1Ds Mk2, and have seen the same thing on a 1Ds.

I will look forward to everyones thoughts.
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Paul Sumi
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« Reply #1 on: November 15, 2005, 12:58:38 PM »
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I have not seen this with my 70-200 L IS, which is not to say that it doesn't happen.

Since this seems to be an issue with just about all your lenses, my first thought was that your camera body needs adjustment/calibration.  But since this has happened with two different bodies, I'm less sure.

Have you had your body/bodies and lenses checked and calibrated by Canon? At least you'll know "officially" if your equipment is in spec.

Paul
« Last Edit: November 15, 2005, 01:46:39 PM by PaulS » Logged

NielsenPhoto
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« Reply #2 on: November 15, 2005, 02:21:01 PM »
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I have had my bodies and lenses all checked out by Canon and they say that they meet their specs.  The test that I am doing is actually looking at a piece of Newspaper and the type at 100%.  I did actually see the same thing at a local camera dealer with a 3rd body.  I probably just need to shoot and not worry about what my lens looks like when shooting a flat piece of newspaper.  What ae your thoughts.
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Paul Sumi
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« Reply #3 on: November 15, 2005, 03:01:07 PM »
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Quote
The test that I am doing is actually looking at a piece of Newspaper and the type at 100%. I did actually see the same thing at a local camera dealer with a 3rd body. I probably just need to shoot and not worry about what my lens looks like when shooting a flat piece of newspaper. What ae your thoughts.
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My first thought is that most lenses are not optimized for close-up work, and I'm assuming you are shooting these tests at close to the lens' minimum focusing distance.

There is also the issue of making sure that the paper target and the film (excuse me, sensor) plane of your camera are both parallel to each other.  This is critical because of the shallow DOF when using lenses near wide open aperture.

Both of these can introduce errors which can make your results less than useful.

My suggestion is to test your lenses under your typical working conditions.  I'm sure you can find real-world situations which let you test your lenses' sharpness, flatness of field, etc.  Then go out and enjoy your gear.

Best,

Paul

ps: if shooting critical closeups of flat objects (photos, paper pages etc) is important, then the best way is to use a macro lens on a copy stand.
« Last Edit: November 15, 2005, 03:28:19 PM by PaulS » Logged

NielsenPhoto
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« Reply #4 on: November 16, 2005, 10:47:53 AM »
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Thanks everyone for the input.  I am enjoying my equipment.  I did talk to another person and said that he did notice that a lot of Canon zooms all show a bit of focus falloff to the left in the particular setting.  In speaking to Canon they even said that what I gain in benefits of zoom, is the tradeoff.  I will stop obsessing now and be thankful I have a camera with exceptional quality and am not $50,000 in debt.  I was told that to compensate for any falloff in focus that I should consider Pixel Genius' Sharpening plug-in and after having tried this I see some noticeable results.  I also looked at the images through Canon's Raw converter"DPP" and see that that makes an improvement as well.  There probably is some compensation that Canon makes as well.  I know that there are lens aberations that can be corrected in Adobe Raw.  I'm sure that Phaseone does not want to spend too much time messing with Canon as they have there one hardware to sell.
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