FZ200 Diffraction Limit - Panasonic Tech Service

Started Aug 27, 2013 | Discussions thread
J C Brown Senior Member • Posts: 1,618
Re: FZ200 Maximum Desirable F-Number to achieve adequate "Sharpness"

Detail Man wrote:

Stephen Barrett wrote:

J C Brown wrote:

Thus for the FZ200 which has a 4000 x 3000 pixel sensor the maximum resolution would be estimated to be 2000 lines per picture height, LPH. That value is within 5% and 10% respectively of the vertical resolution values for the JPEG and RAW images in the DPR FZ200 review.

Just to clarify, when you say "2000 lines per picture height", I assume that this means the same thing as 1000 line-pairs per picture height (1000 white and 1000 black).

Thank you for your comments, Dr. Brown.

I have downloaded your paper and will read it with interest.

From my direct experience in asking Jimmy the very same question, it is true that "lines" is (there) implying line-pairs (per image height in this case). Bottom line, it takes 3 or more individual photosites to reproduce a single line-pair made up of alternating dark/light illumination.

The number of line-pairs recordable is equal to (at most) 2/3 of the spatial sampling elements; and

The number of dark lines recordable is equal to (at most) 1/3 of the spatial sampling elements.

(From Jimmy's excellent paper)

DM ...

Hi DM,

Thanks very much for responding to Stephen's question and for your very complimentary remarks.

While I am in complete agreement with almost all of your reply it seems to me that in your first sentence your statement that "..., it is true that "lines" is (there) implying line-pairs (per image height in this case)." line-pairs should read lines.

Since we were last in touch I've had the opportunity to use my new chart to carry out a test with two DSLRs one with a 21 MP full frame sensor and one with an 8 MP DX sensor. The highest resolution for both corresponded to the 1.5 pixel line however as expected I could recognise a few 1.4 pixel Es in both images and one or two 1.3 pixel Es in the full frame image.

Based on these results I still regard my 1.5 pixel/line "rule of thumb" as a fairly accurate guide to the resolution of any digital camera which employs a Bayer matrix sensor. As stated in my earlier response to Stephen the resolution values at and close to maximum aperture will be reduced as a result of a variety of factors and due to the effects of diffraction the resolution will be reduced as the F/No is increased


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J C Brown

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