Oui, c'est parfait ami colok.

Es tu LE Colok?

De toute façon, comme tu as pu le lire dans ton MP de bienvenue, il est chaudement recommandé de passer par le topic de présentation.

Par la suite, si ton message concerne la photographie, les forumeurs t'aideront avec plaisir dans ta quête. :D

Edit: merci pour ta présentation; j'ai mis ce topic en post-it pour le rendre plus visible.

Oui, je suis LE Colok comme tu dis

Merci pour la mise en avant de mon post .

Merci Benoit pour ceci:

Bonjour les forumeurs,

Colok, le fameux traducteur indépendant de logiciels sollicite notre aide pour la traduction d'Anglais vers Français d'un logiciel technique photo.
Il vous a sans doute déjà aidé par le passé, maintenant, c'est à vous de lui donner un petit coup de main.
Rendez-vous à cette page et bon courage pour la suite.

Chez Photography, il n'est pas coutume de se laisser aller à la facilité.

A bientôt.

:)

ça fait plaisir. :D

Barnack help

Barnack provides an interactive platform for learning about the intrinsic camera parameters and their effect on the depth of field, the hyperfocal distance, field of view, et cetera.

aide (du logiciel) de barnack


Barnack fournit une plate-forme interactive destinée à l'apprentissage, des paramètres intrinsèque à un appareil photo, et de leurs effets sur la profondeur de champ, sur l'hyperfocale, champ de vue/vision ou alors angle de vue ?, etc...

It is named after Oscar Barnack (1879-1936) who designed the first camera using the 24x36 mm format for German microscope manufacturer Leitz in 1913. This camera was coined the "UR-Leica" and is today widely recognised as the precursor to all 35 mm film cameras.

Il est nommé d'après Oscar Barnack (1879-1936) qui a conçu le premier appareil photo utilisant le format 24x36 mm pour le fabricant allemand de microscope Leitz en 1913. Cet invention le «UR-Leica» et est aujourd'hui largement reconnu comme le précurseur de tous les appareils à film au format 35mm.

On peut lire ici un historique : http://www.summilux.net/avis/URLeica.html

Glossary

This part enumerates terms within optical theory. Knowledge of these are required for detailed interpretation of the results presented by Barnack. The section also details a few options specific to the Barnack user interface.

The spatial relationships between the central terms are given in the sketch below.

Glossaire

Cette partie comprend des termes issus de la science de l'optique. La connaissance de ces termes est nécessaire pour jouir de l'interprétation détaillée des résultats présentés par Barnack. Le glossaire détaille également quelques options spécifiques à l'interface utilisateur de Barnack.


The spatial relationships between the central terms are given in the sketch below. J'ai du mal à la traduire celle là...on y reviendra plus tard !

35 mm coc reference
The circle of confusion (coc) in Barnack is specified in terms of a corresponding circle of confusion for a 35 mm film camera. The actual circle of confusion is then calculated for the specific camera and shown in mm (in the right column). For digital cameras the circle of confusion is also displayed in pixels.

Le cercle de confusion (CDC) dans Barnack est exprimé pour un appareil photo au format 35mm (24*36mm ou "full-frame" pour le full-frame je ne suis pas sûr car même si le format est parfaitement équivalent, est ce que la densité de pixel ne joue pas sur le cercle de confusion ?). Le cercle de confusion est alors calculée pour un appareil photo donné et en mm (dans la colonne de droite). Pour les appareils photo numériques, le cercle de confusion est également affiché en pixels.

35 mm equivalent focal length
The focal length required on a 35 mm film camera, or a full-frame digital camera, to obtain a field of view that corresponds to the current field of view.

Aperture
The focal length divided by the effective aperture.

L'ouverture

C'est la longueur focale divisée par l'ouverture réelle

Aperture stop
The diaphragm mechanism that controls the amount of light transmitted in an optical system.

Je n'arrive pas pour l'instant à trouver d'équivalent français pour "aperture stop", je le lis en anglais ça passe sans problème...mais bêtement là en français j'ai du mal ! A part diaphragme si on en croit la définition qui suit en tout cas à priori ça désigne:

Le diaphragme, mécanisme qui contrôle la quantité de lumière transmise dans un système optique.

Blur circle
The diameter of the disc that covers the area that a point, at the image center, is defocused over. Hence, the blur circle for a perfect lens depicting a subject at the focus distance would be zero.

Circle of confusion (coc)
The amount of blurring that one would still perceive as "acceptably" sharp. Hence, the coc is equal to the diameter of an "acceptable" blur circle located at the focal plane. Choosing a circle of confusion is entirely dependent on the application. Often the coc is chosen based on a limiting factor, e.g. visual acuity or pixel size. A typical coc for a 35 mm film camera is 0.030 mm.

Coc from pixel pitch
This Barnack option sets the circle of confusion so that it corresponds to two pixel widths.

Depth of field (dof)
The distance around a subject that will be perceived as "acceptably" sharp (for a given coc). It is the sum of the near depth of field and far depth of field. Formally, this is the depth range where the blur circle is equal to, or smaller, than the chosen circle of confusion.

Depth of focus
The distance around the focal plane that will produce an "acceptably" sharp image (for a given coc).

Diffraction spot diameter
The diffraction spot diameter measures how much a light beam is (Fraunhofer) diffracted by a circular aperture. Barnack calculates the diameter of the Airy disc for light at 550 nm where is contains approximately 84 percent of the total light energy. Diffraction constitutes the upper limit for optical performance. Hence, the circle of confusion should not be smaller than the diffraction spot. Not even for the fantasy construct of an ideal, aberration-free lens.

Effective aperture
The diameter of the physical aperture stop (the diaphragm) at the entrance pupil. This may be different from the actual physical aperture.

Entrance pupil
The virtual image of the aperture stop that can be seen when looking into the front element of a lens. The center of the diaphragm opening seen in this image constitutes the center of perspective.

Far depth of field
The distance behind the subject being depicted in the image as "acceptably" sharp (for a given coc).

Far focus limit
The distance to the end of the far depth of field.

Field of view
The angle the observation takes place under, e.g. observations using a rectangular focal plane can (redundantly) be described by a horizontal, vertical and diagonal field of view.

Focal length
The distance from the second principal point, to the focal plane for subjects positioned at infinity. Think of the distance from a magnifying glass to a piece of paper that the sun is about to burn a hole in. For a thin lens, the second principal point is identical to the lens position.

Focal plane
The plane behind a lens system where a focused image is formed, i.e. where the film or the digital sensor reside.

Focus distance
The subject distance that will be depicted in perfect focus on the focal plane. This distance is measured from the subject to the entrance pupil.

Hyperfocal distance (hfd)
The focus distance that maximises the depth of field for a given circle of confusion. At hfd the range: [hfd/2;infinity] will be in focus. Thus, if the hyperfocal distance is 5 m, then everything from 2.5 m to infinity will be in focus. The hyperfocal distance is also visualized in the graph "Blur Circle vs. Subject Distance" when the circle of confusion (the horizontal green line) remain less than the asymptotic size of the blur circle (red graph).

Image plane
The plane covered in front of the lens by the focal plane at the focus distance.

Magnification
The reproduction ratio of a given image plane on the focal plane.

Grossissement ?
C'est le rapport de reproduction d'une image donnée sur le plan focal. là encore je pense que c'est discutable, c'est peut être un peut trop mot à mot ?

Near depth of field
The distance in front of the subject being depicted in the image as "acceptably" sharp (for a given coc).

Near focus limit
The distance to the beginning of the near depth of field.

Recomposition focus circle (rfc)
The area that a central target can be moved within and remain in focus. This assumes that: i) the recomposition is carried out as a rotation around the entrance pupil of the lens, ii) the focus distance is accurate, and iii) that the object focus field is flat. Notice that these conditions may not be satisfied. The (rarely visible) red and green circles show the bounds of the rfc for an auto focus tolerance of one depth of field (dof).

Limitations

All depth of field estimates assume that the the optical system is fully described by the thin-lens equation: 1/f = 1/c + 1/s, where f, c and s denote the focal length, focal plane distance and focus distance, respectively.

Implicitly, this means that the following assumptions are made:

Symmetrical lens design / pupil magnification is unity / the first principal point coincides with the entrance pupil (in fact, both principal points, both nodal points, and entrance and exit pupils coincide).

No lens aberrations (spherical aberration, astigmatism, coma, distortion, field curvature, chromatic aberration).

Perfect circular aperture.

No diffraction effects.
Strictly speaking, this means that the depth of field estimates are guidelines, rather than hard facts. That said, they can portray reality quite accurately. Particularly for lens designs that are not extremely wide-angle or tele-photo oriented. Secondly, their accuracy is by far sufficient for illustrating the effects on DOF that focal length, aperture, subject distance, sensor size, et cetera will have.

Calculating more accurate estimates would require detailed information regarding the specific lens design, which is typically not available.

Tips

Camera type, focal length, aperture, sensitivity, shutter speed, and, for some lenses, focus distance, can all be read from JPEG images. This provides a handy alternative to set the values using the sliders. Use one of the following methods to load an image.

Click the "Open Image..." button.
Drag and drop the image onto the Barnack window.
Use "Open With..." in Windows Explorer and select Barnack.
Add Barnack as an external editor in your favourite image browser.

A loaded image can be sent to the default image viewer by double-clicking on it in the "Image Plane" section.

Frequently asked questions

Q: The calculations carried out by Barnack do not match my favourite DOF calculator. What's up with that?

A: Some calculators introduce round-off errors, e.g. in the focal length multiplier, or have inaccurate sensor sizes. Such simplifications are typically very fair, but they complicate comparison. Another source of discrepancy is the common assumption, that the focus distance is much greater than the focal length. In that case, it can be justified to use a set of somewhat simpler, albeit slightly inaccurate, DOF equations.

Q: The displayed magnification does not match the one specified by the manufacturer at the closest focusing distance.

A: The closest focusing distance specified by the manufacturer is typically measured from the focal plane. The focus distance set in Barnack is the distance from the entrance pupil which is somewhat closer to the subject. This is also denoted the subject distance. Hence, for a 100 mm life-size macro lens with a closest focusing distance of 0.31 m, a distance from the entrance pupil to the subject of 0.20 m would result in a magnification of 1:1.

Recommended further reading

Science of photography

Understanding Depth of Field

Depth of field

DOFMaster - Depth of Field Articles

Depth of field and your digital camera

Acknowledgements

I thank the following members of the Digital Photography Review forums for their very helpful elaborations, comments and suggestions (in no particular order): Douglas A. Kerr, Detlev Rackow, Leon Wittwer, and David (DRG). I also sincerely thank all the good people contributing to Wikipedia and other online resources with their write-ups shedding light at optical theory.

Bon c'est loin d'être fini, mais je vais essayer de tout faire, ce n'est peut être pas parfait mais je pense qu'on pourra discutier ici sur la meilleure manière de traduire telle phrase, ou tel mot etc...

Merci de ton aide, j'espère que d'autres personnes vont pouvoir nous aider !

Force est de constaté qu'il n'y a pas beaucoup de personnes intéressées :shock:

Dernière édition par Colok le Ven 26 Sep 2008 - 18:34, édité 1 fois

Peu d'érudits, en fait. :me marre:

Dis Colok, tu as essayé sur d'autres forum photo ?

En fait personnellement j'ai un peu de mal sur les termes plus techniques...ce dont tu as besoin !! Même si je comprend le sens.

On pourrait peut être les faire ici sur le forum en français dans une section cours ou optique ? Ca aiderai pour la traduction, mais surtout ça enrichirai le forum

Oui pourquoi pas !

c'est pas que ça ne m'interesse pas, c'est que je vois bien que mon english a quelques (grosses) lacunes

désolée j'aurais bien aimée donner un coup de main

Un excellent outil de traduction, normalement avec ça je me débrouille toujours. [Gratuit]

http://translation2.paralink.com/

Merci à yagelt

Avec l'aide de Philippe, la traduction finale de Barnack ne devrait plus tarder...

La traduction de Barnack est disponible :)

Lire l'article en cliquant ici

beau boulot!

Merci !