Which cameras have an optical low-pass filter (for anti-aliasing)?

Started 5 months ago | Discussions thread
ahaslett
ahaslett Veteran Member • Posts: 7,518
Re: That's what no AA filter + sharp lens gives.

Raist3d wrote:

Mark Ransom wrote:

Paul De Bra wrote:

An AA filter is simple a "blurring filter", but one that blurs just around the pixel level on the sensor. You do want the green and blue pixels to capture a bit of the light from the nearest red pixel when the light is pure green or blue, and then all the permutations of this. With a super sharp lens a perfectly straight one pixel wide horizontal or vertical line in one color can disappear completely from an image and a diagonal one can become a dashed line...

In almost all cases the slightest bit of unsharpness caused by a lens is enough to avoid the lack of an AA filter resulting in Moiré, but when you have a super-sharp lens it can be Moiré galore! I prefer having a super sharp lens + an AA filter over less sharp (consumer-grade) lens and no AA filter. The AA filter does a much better job at spreading light over just the adjacent pixels than an unsharp lens.

I have seen Moiré just like yours, on finely detailed textured textiles. It's a pain to go over each image and selectively apply a Moiré filter in software.

Moiré is caused when the image projected by the lens out-resolves the sensor. As sensor resolutions have gone up this becomes less likely, explaining the disappearing AA filter trend. Any source of blur can act as an AA filter, including misfocus, motion blur, or diffraction limiting. It becomes increasingly uncommon for the stars to align in such a way to make moiré a problem.

But perhaps 20 MP is not enough Fuji avoids a lot of this by using their x-trans CFga

we need to see m43 getting a higher resolution sensor first

Ness Gardens

You can find moiré in this image if you look closely enough.  It’s not an especially sharp lens and the sensor has more Mpix than seems likely for an MFT sensor.  Indeed I’d be satisfied with slightly less Mpix on MFT.

Does it matter to me - no.  Does the lack of an AA filter produce better images - probably.

Andrew

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