The whole question of lens sharpness...

Started Jun 12, 2013 | Discussions thread
Detail Man
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Re: Sharpness in Reasoning ...
In reply to Basalite, Jun 15, 2013

Basalite wrote:

Detail Man wrote:

Basalite wrote:

Detail Man wrote:

Basalite wrote:

Detail Man wrote:

Basalite wrote:

Draek wrote:

Basalite wrote:

What's a "2.4MP monitor?"

A monitor whose resolution is around 2.4 million pixels.

And what "monitor" on the market has such a resolution? I know of none.

As posted by another, just multiply 1200 pixels height by 1920 pixels width = 2.304 Mpixels.

That's not 2.4MP. There is no monitor on the market with 2.4MP.

There's also nothing wrong with viewing images at 100% as that's the only way to tell how sharp your images are.

Nope; another, much more reliable method is to simply make a decently-sized print from it.

Nonsense. If you have a decent quality display you can much more easily determine the level of sharpness than in a print. The printing stage degrades image quality to a certain degree.. As it relates to sharpness, viewing a digital picture on your computer is like looking at a negative or slide with a loupe.

The typical monitor only has around 100 pixels/inch resolution. Some are higher. Printers often can exceed those resolutions. Inks and paper are critical elements in realizing that. Where monitors excel over printers is in contrast-ratio - which is much higher in the case of the typical monitor.

The ability of good monitors of today to show you the true sharpness of your images is not dependent on it being able to display the pixel density needed to produce high quality photographs. Two separate things.

Your words make very little sense.

Which part did you not understand?

The brief declarations that you have not made an effort to explain. You could start by defining what you actually mean by "sharpness". The ability of a medium to depict spatial frequency information depends upon the maximum contrast-ratio as well as the spatial frequency response characteristics. Perhaps that is what you had in mind - but nobody will ever know if you don't explain what you are talking about, so readers can determine your actual understanding of the subject. Please elaborate ...

You are talking "spatial frequency response characteristics" and you can't understand the very simple things I posted?

In fact, in reading this and your other responses to posters on this thread, I don't think that you understand the very simple things that you are posting - and that itself seems to evade you.

You seem to enjoy "sparring" over silly things like where or not any display monitor does or does not have exactly 2,400,000 pixels, and attempting to dismiss outright the thoughts of others - but you are yourself noticeably evasive about the important and central point which renders your bold claims of "objective knowledge" patently hollow - that "sharpness" (like "brightness" and "image quality") are indeed nothing more than subjective terms and phrases which are descriptive only of the implicitly subjective human visual perceptual experience.

Here you betray the subjective, ethereal nature of what you are trying to present as objectivity:

Increasing contrast also doesn't improve sharpness or detail, even if *apparent* sharpness tends to go up.

http://www.dpreview.com/forums/post/51645102

You could still (as I have requested) attempt to provide an objective defintion of what you mean by "sharpness". Otherwise, what you are doing is simply imagining that all the world must surely perceive reality precisely as your eyeballs happen to, or they are otherwise most certainly in error.

What is so difficult to understand? Viewing a high resolution image at 100% on my 27 iMac, or any other good monitor, is like viewing an enlarged negative or slide under a loupe or on a piece of enlargement paper in the darkroom. It's the best way to determine whether an image is sharp. A monitor also does not need to have 300PPi resolution to make that so.

You seem to be forgetting that all images (on any display media) differ in their appearance and characteristics depending upon viewing-size and viewing-distance - decimating your assertion. In fact, your proposed magnification of view (involving re-sampling effects and artifacts at all magnifications other than "100%") at best is depecting something that you claim does not even exist:

"Nearby details?" No such a term. It doesn't even make sense in the context of the discussion.

http://www.dpreview.com/forums/post/51645848

A print, and especially so with the digital processes of today, can easily make a less than take sharp image look "sharp." It is a poor, inefficient and backwards way of determining the true sharpness of a digital image.

I am no particular fan of printed images - but you persist in using an objectively undefinable term.

To assist you in your perhaps unlikely future meditations upon the nature and (the possibility of any) objective meaning of the term "sharpness" that you persist in slinging around as "objective truth", have a look at this statement by Bob Atkins relating to the findings of E.M.Grainger and K.N.Cupery:

... the subjective sharpness of a print corresponds to the area under the MTF curve between the spatial frequencies of (0.5 x magnification) and (2 x magnification) when spatial frequency is plotted on a logarithmic scale.

http://www.bobatkins.com/photography/technical/mtf/sqf1.html

Note that this finding rips a wide and gaping hole in your assumptions that "sharpness" (as subjectively perceived by human visual systems) is independent of the spatial frequency response of the human visual system as affected by viewing-size and viewing-distance, as well as the composite system spatial frequency response and the signal/noise ratio as a function of spatial frequency of the recorded, processed, and displayed image-data. Perhaps food for thought ...

I like to "pixel peep" - but I don't foolishly imagine that doing so allows me to see some overarching and invariant objective perceptual truth. Let me know if you would like to see further indications that your wielding of the ethereal term "sharpness" constitutes little more than a fool's errand.

DM ...

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