The whole question of lens sharpness...

Started Jun 12, 2013 | Discussions
Draek
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We 'need' sharp lenses like we 'need' larger sensors and less noise...
In reply to gdourado, Jun 12, 2013

...but at least it's more fun as a subject to talk about and, given the incredible performance of lenses such as the Pentax SMC Takumar 50/1.4, much, much cheaper as an obsession to get into.

Which is why few in this forum care, of course.

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Re: The whole question of lens sharpness...
In reply to Chris R-UK, Jun 13, 2013

Chris R-UK wrote:

Basalite wrote:

[snip]

There is no such a thing as an image being "oversharp" because of a lens.

But is can certainly be "oversharp" because of excessive sharpening in post processing. I think that that is what the previous poster was referring to.

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Chris R

The discussion is about "lens sharpness."

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Re: The whole question of lens sharpness...
In reply to olliess, Jun 13, 2013

olliess wrote:

Basalite wrote:

There is nothing "vague" about the definition of sharpness.

Ok, then what's your definition of sharpness?

Are you over 40 yet?

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to BertIverson, Jun 13, 2013

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

What's a "2.4MP monitor?"

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

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Draek
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Re: Sharpness not too important on 2.4MP monitor ...
In reply to Basalite, Jun 13, 2013

Basalite wrote:

What's a "2.4MP monitor?"

A monitor whose resolution is around 2.4 million pixels.

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.

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to UtahManSir, Jun 13, 2013

UtahManSir wrote:

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

I don't care about the screen, I want good prints. The screen is irrelevant.

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A good screen will show if it is possible to get "good prints."

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to Draek, Jun 13, 2013

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.

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.

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BertIverson
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Re: Sharpness not too important on 2.4MP monitor ...
In reply to Basalite, Jun 13, 2013

Basalite wrote:

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

1920x1200 is pretty common and close to 2.4MP

Bert

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Detail Man
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Re: Sharpness not too important on 2.4MP monitor ...
In reply to Basalite, Jun 13, 2013

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.

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.

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Midwest
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Re: The whole question of lens sharpness...
In reply to Basalite, Jun 13, 2013

Basalite wrote:

D Cox wrote:

You don't always want a very sharp image, but often you do. It is easy to reduce sharpness, but very hard to increase it.

The ideal is to have a range of lenses in your armoury to suit different occasions. This can include soft focus lenses.

No, it's impossible to increase real sharpness if it wasn't there to begin with.

I wish that more people realized that. I've seen so many images massively sharpened in an attempt to make up for the fact that they weren't sharp to begin with. Of course as you point out that won't work, but people do try, with the result that they get an ugly and painful image to look at.

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PK24X36NOW
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Re: Sharpness not too important on 2.4MP monitor ...
In reply to BertIverson, Jun 13, 2013

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

When viewing the whole image, then the effect is probably not going to be seen in a big way on screen, as you indicated, but, alas, "pixel peeping" is how critical image sharpness can be seen in a way that could only be replicated in film days with a microscope (looking at a slide or negative, not a print, which would not display all of the original's information), and that is where image sharpness differences can be seen on a computer screen. Viewing "actual pixels" on screen is the (size) equivalent of massive print sizes that are seldom, if ever, going to be made by most people. The contrast ratios available in print are also far more limited than viewing on screen.

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BertIverson
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Re: Sharpness not too important on 2.4MP monitor ...
In reply to PK24X36NOW, Jun 13, 2013

PK24X36NOW wrote:

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

When viewing the whole image, then the effect is probably not going to be seen in a big way on screen, as you indicated, but, alas, "pixel peeping" is how critical image sharpness can be seen in a way that could only be replicated in film days with a microscope (looking at a slide or negative, not a print, which would not display all of the original's information), and that is where image sharpness differences can be seen on a computer screen. Viewing "actual pixels" on screen is the (size) equivalent of massive print sizes that are seldom, if ever, going to be made by most people. The contrast ratios available in print are also far more limited than viewing on screen.

Craig,

I agreed with your post.

My post was not to question the wisdom of sharpness when printing large but rather to inspire  those who view on a monitor 99.99% of the time (or make smallish prints) to think about the expensive lens lust. If one fills the frame, kit lens pretty much looks the same as a $2000 super lens.

100% pixel peeping is, indeed, a good/easy way to check sharpness and yes lens sharpness is definitely necessary if one crops/digital zooms or makes large prints.

Since I am one of those 2.3MP monitor viewers and digitally zoom 2X on occasion, I ask that my lens be tack sharp in the center 1/4 region at maximum zoom (the 2X crop tosses the remaining 3/4 peripheral pixels -- leaving me with a 5MP shot)

Cheers,
Bert

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Brad99
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Re: The whole question of lens sharpness...
In reply to gdourado, Jun 13, 2013

Ultimate sharpness is important, but sharpness holding up well all across the frame at wide open apertures is probably more important.

I would like to see more emphasis on flare, contrast and colour in lens reviews.

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Most people do not want sharp vision in their glasses
In reply to Basalite, Jun 13, 2013

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

My next pair of glasses, I will have them correct my sight fully, at least, for the sake of seeing details when I photograph.

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Re: Most people do not want sharp vision in their glasses
In reply to fad, Jun 13, 2013

fad wrote:

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

I doubt that very much.

My next pair of glasses, I will have them correct my sight fully, at least, for the sake of seeing details when I photograph.

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to BertIverson, Jun 13, 2013

BertIverson wrote:

Basalite wrote:

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

1920x1200 is pretty common and close to 2.4MP

Bert

1920x1200 monitors are no longer "pretty common." They are actually rare now. It is also not a 2.4MP monitor, which is no surprise considering there is no such a thing as a 2.4MP monitor.

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to Detail Man, Jun 13, 2013

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.

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to PK24X36NOW, Jun 13, 2013

PK24X36NOW wrote:

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

When viewing the whole image, then the effect is probably not going to be seen in a big way on screen, as you indicated, but, alas, "pixel peeping" is how critical image sharpness can be seen in a way that could only be replicated in film days with a microscope (looking at a slide or negative, not a print, which would not display all of the original's information), and that is where image sharpness differences can be seen on a computer screen. Viewing "actual pixels" on screen is the (size) equivalent of massive print sizes that are seldom, if ever, going to be made by most people. The contrast ratios available in print are also far more limited than viewing on screen.

Just to be clear, it is a mistake to think that just because most people will not be making large prints that their small prints will not benefit from a sharper and therefore high resolution (no, not MP) image. When I used to shoot medium format film i could easily see the difference in even small prints over 35mm film. Then you also have to consider the advantages of being able to crop a more sharper and therefore higher resolution image.

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Re: Sharpness not too important on 2.4MP monitor ...
In reply to BertIverson, Jun 13, 2013

BertIverson wrote:

PK24X36NOW wrote:

BertIverson wrote:

gdourado wrote:

... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? ...

My take on this is simple. If one can fill the frame (avoiding cropping), lens sharpness is usually irrelevant when viewing on a 2.4MP monitor. Viewing a 16MP shot on a 2.4MP monitor means about 4-6 sensor pixels are rendered into 1 pixel on the monitor. In the case of a zoom lens, it only needs to be real sharp at the extreme long end. At lesser FL one will fill the frame (see above).

my 0.02 -- PS pixel peeping not allowed

Bert

When viewing the whole image, then the effect is probably not going to be seen in a big way on screen, as you indicated, but, alas, "pixel peeping" is how critical image sharpness can be seen in a way that could only be replicated in film days with a microscope (looking at a slide or negative, not a print, which would not display all of the original's information), and that is where image sharpness differences can be seen on a computer screen. Viewing "actual pixels" on screen is the (size) equivalent of massive print sizes that are seldom, if ever, going to be made by most people. The contrast ratios available in print are also far more limited than viewing on screen.

Craig,

I agreed with your post.

My post was not to question the wisdom of sharpness when printing large but rather to inspire those who view on a monitor 99.99% of the time (or make smallish prints) to think about the expensive lens lust. If one fills the frame, kit lens pretty much looks the same as a $2000 super lens.

100% pixel peeping is, indeed, a good/easy way to check sharpness and yes lens sharpness is definitely necessary if one crops/digital zooms or makes large prints.

Since I am one of those 2.3MP monitor viewers and digitally zoom 2X on occasion, I ask that my lens be tack sharp in the center 1/4 region at maximum zoom (the 2X crop tosses the remaining 3/4 peripheral pixels -- leaving me with a 5MP shot)

Cheers,
Bert

Small prints also benefit from a sharper lens.

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fad
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Re: Most people do not want sharp vision in their glasses
In reply to Basalite, Jun 13, 2013

Basalite wrote:

fad wrote:

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

I doubt that very much.

My source is my optician and optometrist at a reputable high end establishment.   I'm afraid I have no further source or technical details, and what they mean by full correction.  Possibly they are talking about 20/15 being full correction.  I do not know.  And the context is myopia.

20'/20 is an arbitrary standard and many people have 20/15.  So it could be what they are talking about.

I Googled, and undercorrection is often used with kids on the theory that it will slow the progression of myopia.   This has not been confirmed by studies, however, and has no relevance for adults.

When I next go there, I will get a more technical description of what they meant.

My next pair of glasses, I will have them correct my sight fully, at least, for the sake of seeing details when I photograph.

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