Optical anti-aliasing filter

[iND]

How much sharpness do you think we loose with this filter.
Also known as an optical low pass filter.


http://www.canonwatch.com/eos-5d-mar...ore-sharpness/

I believe most of the medium format sensors do not use this filter

Moire or alias?

[Joel Eade]

I don't know how to quantify the difference but .... it is for this very reason that Nikon offers the D800 with the AA filter and the D800E without the AA filter. There is a perceptible difference I resolution from the reviews I have seen.

[neuroanatomist]

With proper post processing, the impact of a properly designed OLPF (one that blurs out spatial frequencies above the Nyquist limit of the sensor but not below) is minimal. Basically, images from a sensor with an AA filter can be sharpened to a greater degree without detriment than images from a sensor without an AA filter. So while there's a perceptible difference in resolution between the D800 and the D800E on comparison tests (where sharpening is usually not applied at all, or if it is, it's applied identically), you can (and should) apply more sharpening to the D800 output, and when you do, the resulting sharpness will not be significantly different.

OTOH, while you can sharpen an image quite easily and effectively, removing moiré is neither easy nor effective (post processing moiré filters remove the color component of the artifact, but the moiré itself remains in the image).

[Joel Eade]

I believe most of the medium format sensors do not use this filter

I think most medium format cameras (except for some of the very latest models) use a different type of sensor that does not require the same AA filtering. Although detail in medium format is awesome the trade off is the medium format camera sensors do not perform well at high ISO compared to 35mm DSLR's.