sharpness

18:31 Jun 18, 2009 

as you whish!

18:08 Jun 18, 2009 

I don't see any particular benefit in reproducing my comments under your answer. Let's wait an see how the discussion evolves...

17:39 Jun 18, 2009 

à propos de la MTF: I think we are talking of the same thing, since the MTF is the analysis of the rendering of black and white lines through a lens as shown here: http://www.photozone.de/mtf and there: http://www.microscopyu.com/articles/optics/mtfintro.html.
I do agree with you also that specialists in the field seem to avoid the word piqué as I can tell from the Leica official site describing their lenses, talking about contrast and résolution, here: http://fr.leica-camera.com/photography/m_system/lenses/2695....
Unfortunately, Mr. Mohamed Sy has just put a negative vote on the translation pretending it's a canadianism. So I cannot edit it anymore but I can still add a note.
If you whish so, I can add your two last discussion entries in a note as a warning to translators

15:41 Jun 18, 2009 

As indicated elsewhere in this discussion, there is much confusion between objective, technical terms used to define and specify lens performance and the largely subjective term 'sharpness'. The main flaw in this GBK, however, is that the English term should not really form part of any glossary purporting to deal with lens performance characteristics. In that context objectively measurable characteristics such as resolving power, MTF, etc. are used to characterize the ability of a lens to deliver a (subjectively) 'sharp' image to the observer. A lens, as such, is not 'sharp'.

Unfortunately, the mere fact of creating a GBK here, and giving undue prominence to incorrect or confused explanations and so-called ‘definitions’ may help to ‘legitimize’ the use of ‘sharpness’ in an area where the world’s top specialists have chosen to avoid using that word.

15:39 Jun 18, 2009 

If anyone here doubts the complexities behind the term 'sharpness' as applied to lenses (as opposed to images seen on physical supports such as paper), then I recommend reading section 2.1 of http://tech.ebu.ch/docs/tech/tech3249.pdf which describes the European Broadcasting Union's recommended procedure for the measurement of the modulation transfer function (MTF) of professional TV camera lenses. This document states (p. 10):
"The most important single parameter determining picture sharpness is the modulation transfer function (MTF). This quantity can be measured objectively and will reveal a large number of deficiencies and effects in a lens or a lens system."

Interestingly, the EBU recommendation makes no mention whatsoever of 'lens sharpness'. Nor do the other specialist works in my library, such as the classic textbooks "Basic Photography" (Langford, Focal Press 1965) or "Introduction to Classical and Modern Optics" (Meyer-Arendt, Prentice-Hall, ed. 4, 1995). (continued...)

13:55 Jun 18, 2009 

you are right, I found how to post my own definition.
Unfortunately i don't have the time right now to edit it.
If you have a suggestion and/or comment about what I wrote in this discussion under "piqué / netteté" and Fraipont under "le piqué d'un objectif", it seems we both talk about the number of lines per mm that a lens can distinguish

13:34 Jun 18, 2009 

I'm sure it's not mandatory to use an existing webref - and in specialist areas like this, where there is obviously a lot of confusion (= lack of 'sharpness'!), it can be positively counter-productive. On this site it's perfectly legitimate to post an answer based on 'personal experience'. If you (or we...) can provide a better definition of sharpness than anything found on the Internet then so much the better!

12:53 Jun 18, 2009 

I can modify my answer until the first vote has been registered.

As for the definition, it's not mine of course since I understand it's mandatory to find one on the net in order to post an answer.
But it clearly says that, when talking about lenses it's called piqué.
And it's true that, in french, piqué can be applied also to a picture, (in the sense of crispness) hence the confusion.

12:34 Jun 18, 2009 

Thanks for posting your answer. Of course I (and probably FX too) cannot agree with your answer or comment on it directly underneath your answer...

I'm not sure that your 'definition' properly distinguishes between piqué and netteté: "piqué désigne la netteté apparente ...". And you have introduced the concept of "la capacité à distinguer et transmettre les plus fins détails". This is a different parameter, usually known as 'resolving power' in English.

08:16 Jun 18, 2009 

so I did post the answer, please feel free to comment so I can change it if needed

01:26 Jun 18, 2009 

C'est logique que le Termium donne deux termes pour 'sharpness', car ce mot cache deux concepts très différentes ayant deux mots distincts en français. S'il est vrai que les deux mots français sont souvents utilisés - à tort - de manière interchangeable, c'est parceque bcp de gens ignorent de quoi ils parlent. De toute façon, réduire l'affaire à une simple question de 'degré de rendu de détails dans une photo' est hors-jeu car la definition en anglais parle non pas de photos sinon d'objectifs.

01:14 Jun 18, 2009 

TERMIUM (la banque termino canadienne) donne ceci pour "sharpness": netteté/piqué

OBS: Bien que les termes «netteté» et «piqué» soient souvent employés interchangeablement, il existe entre les deux notions une distinction de degré, le «piqué» étant la netteté extrême des moindres détails d'une photographie. En anglais, on pourrait rendre cette distinction par l'emploi d'un déterminant accidentel tel que «remarquable».

21:19 Jun 17, 2009 

Heaven only knows why this GBK has been classified as "Art/Literary" - it's pure technology! As for "Photography/Imaging (& Graphic Arts)" - well, that also leaves me stranded - even though the term is very relevant to television engineering (my specialities include all areas of broadcast engineering).

20:50 Jun 17, 2009 

You can if you :"report a "specialty" level of expertise in the subject field (You have not)"
;-)

20:36 Jun 17, 2009 

vous devriez proposer piqué en traduction et pas seulement en discussion !

20:35 Jun 17, 2009 

tout à fait d'accord avec mediametrix et FX Fraipont.
La netteté est le qualitif d'une image.
Un objectif a un certain piqué.
Ici, la définition proposée en anglais indique sans ambiguïté que l'on s'interresse au piqué de l'objectif.

C'est une notion tout à fait quantifiable, elle se mesure en cycles par mm. Les cycles sont représentés par une alternance de lignes noires et de lignes blanches. Plus la taille minimale des lignes différenciées par l'objectif est petite (avant de ne plus "voir" que du gris), meilleur est le piqué de l'objectif. Ce piqué varie en fonction de la fermeture du diaphragme; les meilleures performances étant atteintes généralement 2 ou 3 diaphragmes au-dessus de l'ouverture maximale.
Un objectif doté d'un bon piqué offre des images plus nettes.

La confusion ici, comme nous l'a expliqué mediametrix, vient que le même terme est utilisé en anglais pour les 2 notions de piqué d'objectif et de netteté d'image.

15:50 Jun 17, 2009 

agree with Mediamatrix: la netteté c'est la photo. L'objectif, c'est le piqué.

"J'ai acheté un 120-400 sigma, et la photo qui sort manque de piqué ( il me semble .... être la cause du mauvais piqué de l'objectif, et il a eu bien raison. ..."
http://forum.nikonpassion.com/index.php?topic=16564.0

"Piqué
La notion de piqué est utilisée en photographie et au cinéma pour désigner la qualité de précision d'une image.

Plus le piqué d'une image sera important, plus l'impression de netteté sera grande.

On associe généralement le piqué à la résolution de l'image, alors que cette notion concerne plus largement la capacité d'un équipement de prise de vue à faire ressortir les détails.

Sur une pellicule, le piqué est exprimé en traits/mm, c’est-à-dire le nombre de traits noirs qu'il est possible de distinguer avec un contraste suffisant. En vidéo, la même notion est exprimée par le nombre de lignes TV. Le piqué correspond généralement aux performances d'un ensemble pellicule/caméra/objectif."
http://fr.wikipedia.org/wiki/Piqué

15:19 Jun 17, 2009 

The English definition of sharpness - which, incidentally, I do not agree with - refers to a characteristic of a camera lens. But all the example sentences refer to the sharpness of an image on paper or some other support.

These are two entirely different concepts and they should not appear mixed up this way in the GBK.

The only result here can be yet more confusion in the translated terms and definitions...