Terminology: Sharpness

Orio · Expire: 2012-12-04

I was just reflecting over the use and concept of the word "sharpness" that we make.

I think that optically, there are three main qualities of a lens:

- color (furtherly distinguishable in fidelity of hues and saturation)

- resolvance (the resolution of lens, it's ability to resolve the fine details)

- contrast (which is the rate of passage from dark colors to light colors, or better said, from shade values to lit values. Graphically, this translate in a more or less steep curve)

I think therefore that sharpness does not belong to these main categories.
It is me personal opinion, that sharpness is a "feeling", or a "sensation", "impression" if you prefer, rather than something scientifically definable.

More precisely, I think that the impression of sharpness derives from the optical combination of the resolvance factor + the contrast factor.

Which is why, I think , some lens manufacturers produce lenses with such high contrast: because they give the feeling of sharpness and let people think that there is also a big resolvance there, when it fact there is not.

On the contrary, there are some low-contrast lenses (especially old lenses) that give the impression of little sharpness, but are really resolving much detail, which comes out of some digital processing very well.

What is your opinion?

Katastrofo · Expire: 2013-11-19

I agree to your comment about sharpness not being scientific. I think it
is highly subjective and dependant upon people's perceptions, how they
see things no matter how imperfectly, and what their own personal
definition of sharpness is. To illustrate: my first marriage was to a lady
who did portraitures, still life, landscapes, and I thought her best work
was in oils. She once held up a red apple and asked me what color do
I see. I naturally said "red" whereupon she said there were at list 14
colors in the apple! This is just one point, mind, but we don't all see the
same thing in the same object, at the same time.

More later,

Bill

rick_oleson · Posted: Wed Feb 28, 2007 4:14 am Post subject:

Yeah, but if you'd started listing off 14 different colors, she would have said "No, you idiot, it's red!"

Smile

=

Katastrofo · Expire: 2013-11-19

Attila · Expire: 2025-11-18

Ide nem lehet, csak linkelni ezt haszn�ljuk az angol forumon http://imageshack.us/, ide felt�ltheted azt�n lehet linkelni.

Orio · Expire: 2012-12-04

Rob Leslie · Joined: 20 Mar 2007 Posts: 1103 Location: UK Swindon

I agree with. 'Some lens manufacturers produce lenses with such high contrast: because they give the feeling of sharpness and let people think that there is also a big resolvance there, when it fact there is not.'
And
'On the contrary, there are some low-contrast lenses (especially old lenses) that give the impression of little sharpness, but are really resolving much detail, which comes out of some digital processing very well.'

I have never equated contrast with sharpness but it is something that is needed for lens resolution charts, often a useless way of measuring the performance of a lens, especially a BW chart.
Resolving detail is a subjective thing which some see as clearly defined contrast between edges and others (Like me) prefer to see as clearly defined graduations. There is a difference and with that �Difference� we are back to the question of contrast vs. sharpness.
If it was as easy as sharpness = contrast we PS users would have no problem producing sharp pictures from any duff lenses by our skillfull use of USM. We can't.
There is a lot of real Tech stuff of the subject of sharpness on Luminous landscape

PS There are lots of 'Soft' lenses which are very sharp and often cost a lot of money.
There are also other factors that effect sharpness. For example Digital noise will destroy detail. I encountered this when I had a Sony Alpha. At 400asa and above shadow detail was destroyed by the noise. On the JPEG output they just reduced the shadow range to overcome it.

Jigt · Joined: 16 Mar 2007 Posts: 412 Location: Belgium

Sharpness for my is an impression, mostly a picture looks sharper if the object is surrounded by a smooth background.

@ Rob see in your signature a lens: Fujinon f4.5 400mm, never heard of it. Can you tell me more about it?

Guido

Orio · Expire: 2012-12-04

Jigt · Joined: 16 Mar 2007 Posts: 412 Location: Belgium

I have a book on colours, heavy stuff.

written by ITTEN.

Guido

Jigt · Joined: 16 Mar 2007 Posts: 412 Location: Belgium

Here is the link:

Itten

Rob Leslie · Joined: 20 Mar 2007 Posts: 1103 Location: UK Swindon