FZ200 Diffraction Limit - Panasonic Tech Service

Started 8 months ago | Discussions thread
Detail Man
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Re: FZ200 Diffraction Limit - Panasonic Tech Service
In reply to sherman_levine, 8 months ago

sherman_levine wrote:

LTZ470 wrote:

Received a reply back from Panasonic Tech's on the FZ200 and where the Diffraction limit begins:

Dear Valued Customer
Case Number:30742743

Thank you for your inquiry, the diffraction (FZ200) starts 3.5 to 4.0.
We hope this information is helpful.Thank you for contacting Panasonic.

Interesting that the response was so brief - but it's consistent with your posting yesterday that your images start getting soft at apertures narrower than 4-4.5.

It's consistent also (albeit with a different absolute) with Ian's ZS19 results, where the resolution varies only with aperture, and is independent of zoom.

http://www.dpreview.com/forums/post/51807115

I suspect their answer is more to "When does diffraction become the limiting factor in resolution" than "When does diffraction start"....since diffraction is of course always with us. The zoom lens is far more complex than the thin single lenses for which Airy discs are calculated, and it's not trivial (at least for me) to extract the relationships among the physical iris diaphragm diameter, the distance from the sensor, and the magnification of the zoom mechanism by the front lens as the zoom is changed.

I can tell you from plenty of actual "experience" that the kids who work at Panasonic's "Technical Support" facility in Virginia are universally clueless in the extreme - and so are their "stupervisors".

For those who like to read, you might find yourself ruminating on the non-trivial details involved:

http://www.dpreview.com/forums/thread/3475094

When DIWA Labs was still around, they used DxOMark's testing rig to test (JPGs) from Pansonic stuperzooms. For the most part, MTF(50%) and Lens-Blur (in BxU) was highest at the lower F-Numbers (2.8-4.0), reducing somewhat after that. So, the "sweet spot" was more of a "sweet band" located near the bottom of the F-Number adjustment range.

It is important to understand that numerous factors affect the composite system spatial frequency response - lens-system diffraction is only one of them (and tends to be a relatively minor factor, until F-Numbers are reached where "extinction" of the lens-system (only) MTF begins to result in some (gradual, not "sudden") losses at the very highest spatial frequencies.

Details surrounding what happens (and how it happens) given various different parameters involved are discussed in the thread that I provide a reference link to above. These are complex matters.

DM ...

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