Nex 7, already can see much less moire problems

Started Aug 26, 2011 | Discussions thread
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RussellInCincinnati
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Nex 7, already can see much less moire problems
Aug 26, 2011

Thanks RicksAstro for the nicely prepared raw file example, showing the moire problem (false colors and false patterns in fine details) of the Nex 5 reduced to insignificance in the Nex 7 . Of course that is the moire pattern that is obtained with the particular lens and subject of the test in question. The reader should be able to tell which of the sharpened samples below is from the Nex 5N, and which from the Nex 7.

Moire false-color problems appear when fine details are rendered by a lens and exposure situation, onto a sensor that has pixels too large to faithfully record those tiny details.

Thus to fix moire problems with sharp lenses, you can add an "AA" or anti-aliasing filter atop the sensor, a diffusing piece of glass to purposefully reduce the effective image resolution--so that the lens does not resolve and project any tiny details. That's what most cameras do.

Or, you can increase the resolution of the sensor so that once again the lens resolution is inferior to the sensor res. That's possibly what the Nex 7 has achieved.

With a good lens on the Nex 5, sharply focused and not blurred, especially in raw files, the lenses are indeed roughly the same or greater resolution than the sensor, because the Nex 5 does not have the typical strong AA filter of most digital cameras. Thus a lot of Nex images look really sharp and clear, but some of them show false color moire patterns. Witness the left-hand image in the sample above.

With the Nex 7, I don't care whether or not the picture on the right looks sharper or not, but hallelujah, the Nex moire problem has been knocked out of the park. A problem that is some times absolutely impossible to deal with in raw files, like PMong's aerial photos of a Los Angeles stadium seat array.

Of course all "decisive" judgements about the new Nex 5N and 7 cameras must wait until we see production models. Maybe all the Nex 7 has is a stronger AA filter, reducing moire artifacts and resolution, rather than giving us the same or better resolution with no moire artifacts. And maybe there are no effective differences in Nex 5 vs Nex 7 jpegs, and maybe the raw conversion used in the above example just happens to be of a kind that the Nex 7 works much better with in this one photo and no other. Maybe with a different raw converter or lens or subject or exposure there would not be such improvement.

But one way or another, so far, it looks like the noticeable-for-some-users moire problem of the Nex 3/5 family is greatly ameliorated in the Nex 7.

This post is not meant to convince people that aren't encountering moire problems with their Nex 3 or 5 models, that they should get a Nex 7. Nor is this post a judgement about what the shipping Nex 7 will be like, nor is it a statement that the Nex 7 is a good deal, or a good camera. Nor is it a statement that the test photo represents a lens or subject that any of us will ever want to use or experience.

It is merely an observation that one of our faithful forum contributors have already shown a significant-to-some improvement in one aspect of the prototype Nex 7 sensor. Overall the Nex 5 sensor may be a much better sensor, or a much sharper one, or faster or better high ISO or whatever.

Am simply narrowly observing a moire pattern improvement in Nex 7 vs Nex 5N at this very early stage. The beautiful thing would be if performance follows theory, and that the Nex 7 is "naturally" more moire resistant than the Nex 5, without having a stronger AA filter.

We've talked about this thing before in this forum. Some day with 96 megapixel APS-C sensors and no AA filter at all, there ain't gonna be moire problems.

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