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Author Topic: AA filter question  (Read 1269 times)

Greg D

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AA filter question
« on: October 08, 2012, 02:13:56 PM »

Will the sharpness benefits of an AA-filterless sensor show up with less than the best lenses (i.e. good primes)?  I'm not talking about cheap lenses, just good standard zooms.  I'm thinking in particular about the new AA-less version of the Pentax K-5, and zooms such as the Pentax 16-50 2.8, 16-45 f/4, 17-70 f/4, or the Tamron or Sigma 17-50 f2.8s.
Thanks for any insight.
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Re: AA filter question
« Reply #1 on: October 08, 2012, 02:35:25 PM »

Yes you will see a difference with modest lenses @ 100%. AA filter-less sensors are a personal taste decision, I personally prefer them. I have a K5 and think the AA filter-less version would be a very good choice. The 17-70 f4 was the best of the zooms that I tested.
Marc
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Marc McCalmont

ErikKaffehr

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Re: AA filter question
« Reply #2 on: October 08, 2012, 04:24:25 PM »

Hi,

Not sure about the benefits. Probably any lens stopped down to f/8 will show some aliasing on a camera without OLP filter. If you stop down to f/11 or f/16 you avoid aliasing.

Now, if aliasing is a benefit or not is really up to perception. Think about a thin line, one pixel wide. A sensor with aliasing will show a line that has a staircase effect or disappears and reappears. The OLP filter will smear out the line, so it seems to be continuos but it will also be less sharp.

The natural resolution limit of a sensor is called the Nyquist limit. On an OLP less sensor the sensor will produce fake detail. A low frequency pattern will be seen instead of a gray mass.

If you check out the enclosed image from DPReview you see a red line representing the Nyquist limit. Anything below that line is fake information (low frequency aliases of a high frequency information). But it is perceived as real detail.

Best regards
Erik



Will the sharpness benefits of an AA-filterless sensor show up with less than the best lenses (i.e. good primes)?  I'm not talking about cheap lenses, just good standard zooms.  I'm thinking in particular about the new AA-less version of the Pentax K-5, and zooms such as the Pentax 16-50 2.8, 16-45 f/4, 17-70 f/4, or the Tamron or Sigma 17-50 f2.8s.
Thanks for any insight.
« Last Edit: October 09, 2012, 02:12:17 AM by ErikKaffehr »
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