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    T3i 3x Crop Appears to Reduce Moire
    #1
    Senior Member John Froton's Avatar
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    I just got my T3i today and did a quick test before sundown and the result looks promissing. I shot some brick buildings and shingled rooftops --- first with shots with a Tamron 17-55 zoomed in NOT in crop mode, followed by shots in 3x crop mode with same lens at wide end. There was moire all over a roof of one buildings in one of the first shots --- no moire on the same roof in the same setting on the second shot. Both shots looked pretty similar in focal length otherwise.

    Tomorrow I will do a serious test in broad daylight

    At 3x the crop feature is really nice and will be even nicer if it truly helps eliminate some issues with moire and/or aliasing. Of course the extra telezoom is nice in some cases but is also of little use if you need really wide shots.


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    I've really been wondering about this so
    Thank you for the info...look forward to the test!


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    #3
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    In theory, this is correct, because when you zoom in on the sensor you're not skipping lines. In theory.

    The "3x" shouldn't entirely eliminate moire/aliasing -- but the "10x" should entirely eliminate moire/aliasing, in theory. It should also create the "deep focus" seen on any tiny sensor traditional video camera.


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    Senior Member maranfilms's Avatar
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    Cool, thanks for posting, I will keep that in mind for future shoots.


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    Senior Member Samuel H's Avatar
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    in theory, and in practice, 3x eliminates aliasing, but also creates some softness, as it uses a bayer pattern of approximately 1730x974 to generate the image

    there are some tests on this thread:
    http://www.dvxuser.com/V6/showthread...d-sales/page12


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    #6
    Senior Member John Froton's Avatar
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    Ok, I did more testing today and I was able to repeat the crop mode eliminating moire in brick patterns. I also did test shots for jello-vision and it seems that the crop mode does not do anytrhing to reduce that.

    The bottom line is that the 3x crop does offer a workaround for moire and perhaps aliasing at the cost of softening the image a tad and losing your wide focal length. The digital zoom at 3x looks way better than SD and looks to be just a slightly upscaled and softened version of what the Canon's do at 1080p. As you go to 10x you start getting crap.

    For some shots I think this will be a great feature and tool to use.


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    #7
    Senior Member Samuel H's Avatar
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    Quote Originally Posted by John Froton View Post
    The bottom line is that the 3x crop does offer a workaround for moire and perhaps aliasing at the cost of softening the image a tad and losing your wide focal length.
    plus you're now using a small part of the sensor and loose some shallow DoF (suddenly my fastest lens, which is f/1.8, delivers the same DoF as an f/5.6)


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    #8
    Senior Member John Froton's Avatar
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    That's a good point.

    so the way I see it . . .

    Pros - The 3x crop can extend the zoom range of your lens without light loss and it can reduce or eliminate moire and aliasing.

    Cons - it softens the image through slight upscaling, it sacrifices wide focal lengths and it sacrifices shallow depth of field.

    I can see myself using it when the drawbacks don't interfere too greatly with the needs of my shots. For shooting video, this feature mainly influenced me to choose the T3I over the 60D.

    What would really be nice is a Canon DSLR that will shoot to a 4K format


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