FZ200 Diffraction Limit - Panasonic Tech Service

Started Aug 27, 2013 | Discussions thread
J C Brown
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Re: FZ200 Maximum Desirable F-Number to achieve adequate "Sharpness"
In reply to Stephen Barrett, Sep 2, 2013

Stephen Barrett wrote:

J C Brown wrote:

I'm pleased to hear that you are finding my report useful but as I have no idea why you would expect red to give the poorest resolution I'm puzzled by your statement "I find the graph of resolution for the different colours surprising".

The reason that I expected red to have the poorest resolution is that the Rayleigh criterion says the angular resolution is proportional to wavelength.

Visible violet ~ 400 nm
Visible red ~ 650 nm

So the violet end of the spectrum should be able to resolve the smallest angles and red should be poorest.

Thanks very much for the explanation for your comments.

I agree that your statement is correct for the resolution of the lens. However from my understanding of the construction and operation of a digital camera and the evidence of my tests I regard the resolution as being determined by the dimensions of the pixels on the sensor.

For the small sensor in the FZ200 the sides of each of the square pixels have a length of approximately 1.52 microns. As each pixel in the sensor is covered by a red, green or blue filter it receives only light of the colour of the filter which covers it. The colour of each filter depends on its position in the Bayer matrix which as it consists of a square of four pixels will have 3.04 micron long sides.

The colour assigned to each pixel in the final image is determined by a demozaicing algorithm which combines the value for that pixel with the values recorded from adjacent pixels to define the values of the red, green and blue components for that pixel.

I hope that helps.

Jimmy

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J C Brown

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