The whole question of lens sharpness...

Started Jun 12, 2013 | Discussions thread
Detail Man
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Re: Back on an ethereal track and a word about obsessing
In reply to Klaus dk, Jun 14, 2013

Klaus dk wrote:

Detail Man wrote:

Klaus dk wrote:

Basalite wrote:

fad wrote:

Optometrist do not correct you vision fully. It makes people feel uncomfortable.

I doubt that very much.

I don't. Both my present and my former optician told me the same thing. Both are/were reputable professionals.

I wonder in what particular respects they modify the optical corrections, and if there exists some common standard numerical amount(s) by which they modify such correction parameters.

I also wondered, but if I asked, I have forgotten the answer. I supposed they know what they are doing. But are we not sidestepping the actual discussion here?

I find that particular information more interesting than the "discussion". First, (the "discussion") is premised upon the usage of a term without clear objective definition that describes a subjective perceptual impression. Like the term "brightness" and the phrase "image quality", "sharpness" is a term that is bound to mean and to constitute different things to different observers.

These kind of (non) discussions are all too common on these forums - and accomplish nothing.

If we are talking about the lens have a minimum of optical aberrations and a correspondingly high spatial frequency response (MTF), then I am all for that. There exists a plethora of other effects (in addition to lens aberrations) that diminish that (de-focusing, diffraction, optical filtering on image-sensors, image-sensor noise sources, de-mosaicing, in-camera and/or post-processing manipulations including noise-reduction, display/printer reslution and contrast-ratio limitations, viewing size, viewing distance, ambient lighting and human visual acuity).

Wishing for a lens that is "soft" is like wishing for an image-sensor with some limited number of photosites. It makes little sense to me to desire to impose limitations over and above all of the limitations that already exist - especially when RAW format recording and digital signal processing offers such a wide "spectrum" of ways by which the final image can be "softened" to taste.

(To me), longing for marginal lenses is akin to dreaming of audio amplifiers with vacuum-tubes so that the linearity, bandwidth, and signal/noise ratio will be compromised, based on some desire to always see the world through a particular type of rose-colored glasses smeared with vaseline. It might sound great for certain limited bandwidth program material, and fail miserably where it comes to reproducing orchestral music replete with critical high frequency information.

I agree with others, that the sharpness of a lens is a good thing and I think price considerations will keep sharpness freaks in check.

Advances in technology is not driven by a "good enough" attitude. Advances are only possible because lensmakers are obsessed with sharpness, sensor designers are obsessed with pixel count and high ISO noise and customers are obsessed with value for money.

If noone obsessed, we would still be using 1 MP cameras costing 2000 USD.

My wife insists, that all my lenses can look into the future and show how she will look in ten years time, but that is another matter entirely

If we had keen vision and feeling of all ordinary human life, it would be like hearing the grass grow and the squirrel’s heart beat, and we should die of that roar which lies on the other side of silence.
- George Eliot

DM ...

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