FZ200 Diffraction Limit - Panasonic Tech Service

Started 8 months ago | Discussions thread
Detail Man
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Re: FZ200 Maximum Desirable F-Number to achieve adequate "Sharpness"
In reply to Ianperegian, 7 months ago

Ianperegian wrote:

Stephen Barrett wrote:

If aspects such as intensity and the particular shade or hue can move "red" from worst to best, how can the graph be used? My interpretation of the graph is that the average resolution decreases from approx 1800 LP/picture height at f/3 to about 1350 at f/11 and that there are colour/ intensity / hue / tint variations of approximately +/- 200. Would that be a fair interpretation if you were taking a picture of, say, a red flower and could not assess what kind of red it was?

Hi Stephen, in relation to colour resolution/intensity/contrast, some tests I did a while back
using Jimmy's coloured Es chart with different coloured backgrounds might be of interest: http://www.dpreview.com/forums/post/51413807 .

I prepared a table comparing my resolution results with the visual contrast ratio of coloured text on a coloured background according to international standards for webpages. As shown in that table, in most cases, a high contrast ratio corresponded with a high resolution of the Es. However, there were cases where the ratio didn't successfully predict the outcome for resolution.

From the results I prepared a listing of colour combination that gave very good resoluton and those which gave poor resolution, as copied below:

Combinations giving very good resolution:

Red on cyan, or white, or yellow, or pale grey

Green on dark blue Blue on cyan, or white Magenta on white, or pale grey, or yellow

Cyan on dark blue, or black, or dark grey

Yellow on dark blue, or black, or dark grey

Black on white, or green, or pale blue, or pale grey, or cyan.

Combinations giving poor resolution:

Red on dark blue, or magenta, or mid grey

Blue on black, or dark grey

Green on pale blue, or cyan

Magenta on red, or mid grey

Cyan on pale blue, or green Yellow on pale grey, or white

Black on dark blue.

I suggested that optical crosstalk on the Bayer matrix might possibly be implicated in the cases of low resolution.

And I think that you seem to have made a reasonably good case. On a pure pixel-pitch level, one might thing that the FZ50 image-sensor (with ~ 2 Micron photosites) might (possibly, for that reason) fare better than the smaller image-sensors models (with ~ 1.5 Micron photosites).

However, I would think that such inter-channel "crosstalk" probably also is very much related specific photodetector placement geometries (and micro-lenses, if present along with the unique to each image-sensor's "filter stack") - and becomes harder to avoid as photosite sizes shrink.

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