Diffraction Limit

Started Aug 28, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,789
Re: By other numbers ...

Steen Bay wrote:

Great Bustard wrote:

Paul De Bra wrote:

With a sharp lens mounted on the E-M5 you can certainly see the effect of diffraction at f/8 versus e.g. f/5.6 when looking carefully at 100% pixel level on a sharp monitor. Does that qualify as noticeable?

I typically view my images on a 1920x1200 pixel 24" monitor. At that resolution and monitor size such measurable difference in sharpness is not noticeable. When I take shots with the 12-50 or 20mm there is no noticeable difference in sharpness on my monitor. When viewed at 100% there is a visible difference, and also a visible decrease in sharpness on the 20mm when going from f/5.6 to f/8. But for practical use there is no noticeable difference.

Most of the discussion about diffraction is about differences and softening that isn't really visible when admiring a photo, only when pixel-peeping.

...the effects of diffraction softening depend on the display size of the photo, the viewing distance, the visual acuity of the viewer, the other sources of blur in the photo, and the QT (quality threshold) of the viewer.

Took a look at FZ200 in IR's 'comparometer' to see what kind of resolution we're talking about here. The resolution test chart is shot at f/4 (DoF/diffraction equivalent to f/22 on FF and f/11 on mFT), and I'd say that the resolution is about 2200 lw/pH. Not that bad for a sensor with 3000 vertical pixels.

Yes, 73% of the spatial sampling frequency is a phantasmagorical fiction where it comes to meaningfully differentiating blcak/white line-pairs in any image. 1/3 (33%) of the spatial sampling frequency is well established as the (actual) perceptual limit (in the square-wave case of line-pairs, as opposed to sinusoidal variations, as in "zone-plates"). The rest is just "fudging" ...

It comes down to a combination of how much aliasing distortions as well as sharpening distortions (further) multipying that wich one's eyeballs can stand. Such declarations are but an arbitrary "numbers game" that are entirely subjective (and even variable for a single individual over time). One need look no farther than this very site itself to see such things in action.

The world, however is largely made of Fudge, and chocolate addicts are always looking for high "potency" product.

Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow