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As I shoot portraits and weddings I'd much rather not have an AA filter on my sensor.
Much sharper images, so much so I'm testing out medium format for my portraiture.
Once you get to around 40mp the need for an AA filter is greatly reduced.
Much sharper images, so much so I'm testing out medium format for my portraiture.
Once you get to around 40mp the need for an AA filter is greatly reduced.
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As a Computer Science major with an Electrical Engineering concentration, I have a fairly good grasp on the general concepts of aliasing and filtering. What I don't understand is why having an anti-aliasing filter should ever be problematic for images. As I understand they are implemented as low-pass filters in front of the sensor, which prevents high-frequency data (that data in which there is extremely rapid change from pixel to pixel) from getting through to the sensor, while letting everything else in. High-frequency data could be noise or moire, but the threshold for "bad" data is so high that there's no reason that the data you actually want should ever be stopped by it. That is to say, the local frequency of moire is so much higher than the frequency of, say, a transition from a person's clothing to the background behind them, or even the transition between edges on a repeating pattern, that I don't understand why having an anti-aliasing filter could ever be detrimental to any but the most extreme images.
Please enlighten me.
Please enlighten me.
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J
JerryBruck
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@Positron: Does this do it?
http://nikonrumors.com/2012/02/04/why-remove-the-anti-aliasing-aa-filter-in-the-nikon-d800e.aspx/#comment-230160
I don't pretend to know how significant the advantage will be, but it's interesting that several posters who seem to know, declare that moire effects are not triggered very often.
http://nikonrumors.com/2012/02/04/why-remove-the-anti-aliasing-aa-filter-in-the-nikon-d800e.aspx/#comment-230160
I don't pretend to know how significant the advantage will be, but it's interesting that several posters who seem to know, declare that moire effects are not triggered very often.
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Positron said:As a Computer Science major with an Electrical Engineering concentration, I have a fairly good grasp on the general concepts of aliasing and filtering. What I don't understand is why having an anti-aliasing filter should ever be problematic for images. As I understand they are implemented as low-pass filters in front of the sensor, which prevents high-frequency data (that data in which there is extremely rapid change from pixel to pixel) from getting through to the sensor, while letting everything else in. High-frequency data could be noise or moire, but the threshold for "bad" data is so high that there's no reason that the data you actually want should ever be stopped by it. That is to say, the local frequency of moire is so much higher than the frequency of, say, a transition from a person's clothing to the background behind them, or even the transition between edges on a repeating pattern, that I don't understand why having an anti-aliasing filter could ever be detrimental to any but the most extreme images.
Please enlighten me.
An AA (low-pass) filter can be problematic when the frequencies it blurs are larger than the frequencies the sensor can still capture properly, and to a lesser degree, when it does not blur frequencies that are too small to be usefully capture properly. Generally speaking, the latter is not really a problem, and I would opt for that over no AA filter at all. However, if the AA filter is blurring frequencies that are still resolvable by the sensor, then that is eating away at GOOD detail, and thats not a good thing. Some of Canon's camera's have had low pass filters that are just a bit too aggressive, resulting in softer images than the competition at similar pixel sizes. That means your losing a small amount of detail (permanently, although you can use post-process sharpening to "recover" it...or rather, lessens softness), and losing it without cause.
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