L'Argentique pour la pure beauté de la photo ...

[Verso92]

400 paires de lignes sur un film 24 x 36...le meilleur n'a jamais dépassé 80 en contraste faible  ...sur du microfilm lith tiré en noir et blanc purs, et encore je voudrais voir çà...tu demandes à Zeiss de te prêter leur 35 mm, tu le poses sur un M9 puis sur un M7 avec le film le plus fin du marché, et tu vois toi-même !

Kodak annonçait 200 pdl pour son Technical Pan 2415 en développement "trait", il me semble. En utilisation "photo", je suis comme JMS : j'aimerais bien voir ça...

[waldokitty]

Est ce à dire que les liens fournis par Joël Pierre sont bidons? la maison semble sérieuse pourtant.

[Joël Pierre]

Est-ce à dire que les liens fournis par Joël Pierre sont bidons ? La maison semble sérieuse pourtant.

Plus que sérieuse. Austère même.

http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_30_MTF_en/$File/CLN_MTF_Kurven_EN.pdf

http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/$File/CLN_MTF_Kurven_2_en.pdf

http://www.zeiss.com/C12567A8003B58B9/Contents-Frame/73D528C09B620A11C125697700548CD6

[b]Resolution of camera lenses where are the limits—and why?[/b]

Some users of Zeiss lenses are so enthusiastic about these optics that they believe Carl Zeiss can do wonders. Well, this is not exactly true. The fact is: Carl Zeiss has to adhere to nature’s laws just as anybody else. So far, Carl Zeiss’s physicists have found no way around it.

One of these laws defines the resolution limit of any optical system, any camera lens, even a perfect one with absolutely no lens errors. It is the law of diffraction. This law states that a sharp point in an object will not correspond to a sharp point in the image thus having a diameter of exactly zero, but rather to a small diffraction disc (physicists call it ”Airy disc”). This disc has a certain dia-meter, which varies with the aperture of the imaging system. The smaller the aperture (e. g. f/22) the larger the disc. And the larger the disc, the lower the resolution!

So, even a perfect lens with no lens errors is limited in its resolution! (Such a perfect lens does not exist. Even the most sophisticated lenses on this planet, the Carl Zeiss S-Planar lenses for the semiconductor industry are only approximations to the perfect lens, although very close ones.) Thus the term ”diffraction-limited” has become the synonym for lenses that are so good their only per-formance limit is the law of diffraction. According to this law no camera lens used in photography, still or motion, can produce resolutions higher than given in the following table (Approximate, rounded off values for white light spectrum of even energy distribution. In unevenly distributed spectra of gas discharge light sources somewhat higher resolutions may be achieved.)


f-no......................resolution
.............................(line pairs per millimeter)
.45.......................... ...35
.32.......................... ...50
.22.......................... ...70
.16.......................... .100
.11.......................... .140
...8......................... ..200
5.6.......................... .280
...4......................... ..400
2.8.......................... .560


In practical photography other limitations of resolution occur, too. The existing depth-of-field concepts, for example, lead to a limit at 30 line pairs per millimeter, simply because they assume that the image of a sharp point may be considered sharp as long as the unsharp disc it actually is (called the ”circle of confusion”) grows no larger than 1/1000th of the focal length of the respective standard lens. In 35 mm photography only 1/1500th is allowed. 1/1500 th of the 50 mm standard focal length equals 1/30th mm. So 30 fit into one mm, which means, we are talking 30 line pairs per millimeter (CLN 1 has more details in ”Depth of Field – An Insider’s Look Behind The Scenes”, an article that meanwhile has been reprinted in many publications around the world). This is about the same limit set by diffraction for f/45 which was an aperture setting quite popular with 5 x 7 inch large format photography, producing images that can be viewed without any subsequent magnification.

Today’s high quality color films do reach resolutions in the region of 140 line pairs per millimeter with Kodak Ektar 25 leading the field at 200! The full resolution potential of these films cannot be utilized with existing depth-of-field concepts nor f-settings of f/11 and beyond. On the other hand all real lenses on the market today are limited not only by diffraction, but by lens errors also. Some of them quite heavily.

Carl Zeiss has always strived to develop very elegant sets of lens error corrections and to deliver a high degree of lens performance, second to none. So, with normal Carl Zeiss lenses set at f/8 and f/5.6 resolutions at the very limits of the best color films have been reached.

Objects of 4 millimeter in size (approximately 1/6 of an inch) have been imaged from almost 400 meters distance (more than 1.000 feet) with a 100 mm Carl Zeiss Makro-Planar lens at f/5.6 and a Contax RTS III 35 mm SLR camera featuring the unique Contax vacuum pressure plate. Similar results were obtained with Contax AX 35 mm autofocus SLR, Contax RX 35 mm low noise SLR and Makro-Planar 60 mm, Planar 85 mm f/1.2, Planar 100 mm f/2, Aposonnar 200 mm f/2, Vario-Sonnar 28–85 mm and 35–70 mm zoom lenses, even with moderate priced Planar 50 mm and Distagon 28 mm.

…

[Joël Pierre]

Resolutions on the same level have been achieved with Carl Zeiss lenses in Hasselblad medium format cameras, proving that at Carl Zeiss, medium format lenses, contrary to popular belief, offer no lower resolution than the very best 35 mm lenses.

Other camera systems which achieve performances in the same premium class with their Carl Zeiss lenses include the medium format SLR cameras of Rollei fototechnic with the Rolleiflex 6008 integral as their latest top of the line product and the discontinued Rolleiflex 3003, the only 35 mm SLR with inter-changeable film backs since the demise of the Zeiss Ikon Contarex and Contaflex.

The most obvious limitation of resolution in everyday photography, however, is unwanted motion with handheld cameras. Even a seasoned photographer with a very ”calm” camera will hardly find resolutions higher than 40 line pairs per milli-meter in his photographs unless he uses an adequate tripod. CLN will detail on this topic in a later issue.

…

[Joël Pierre]

How to determine the resolution actually reached in a photograph a practial example

Let us assume we are about to take a photo of a landscape. Somewhere there is a farm. And a wooden fence. Its white painted vertical slats, each about two inches wide (which we will
convert to 50 mm) and spaced with about two inches distance to the next slat (we may have to go there and measure these values), stand clear against some darker background. This wooden fence represents a structure of dark and bright lines similar to those in resolution test targets. Let us further assume that we are using a Carl Zeiss 50 mm Planar standard lens and a Contax SLR camera. The fence may be a quarter of a mile away (as a map can tell us or a binocular with a distance measuring device).

Now, let’s make a rough calculation of the resolving task facing our imaging system: From a quarter mile distance, which is about 400 meters, the reduction ratio, let’s call it ”r”, for the fence to be imaged on film with the 50 mm lens, is as follows: r = focal length divided by object distance, expressed in the same unit. This gives: 50 millimeters /400 x 1000 for a ratio of 1/8000.

So the original subject, the farm and the fence, and every detail will appear at 1/8000th of its original size in the negative (or slide, whichever you prefer). One slat plus one space, both representing one line pair in the original subject, are 4 inches wide. This equals roughly 100 millimeters. Reduced by the reduction ratio of 1/8000 it should appear on film with this width: 100 millimeters / 8000 = 1/80 of a millimeter. So 80 fit into 1 millimeter, which means, we are about to resolve 80 line pairs per millimeter.

Can our imaging system handle this task? For a Zeiss Planar in a Contax camera and any modern 100 ISO film, 80 line pairs per mm is an easy challenge, if we focus precisely and avoid unwanted vibrations (by using a good tripod). So let’s go ahead and take the picture. The fence should be well resolved in our photo.

Or, the other way round: If we took the photo and later found the fence resolved, then we knew we did achieve at least 80 line pairs per millimeter.

[Verso92]

Et en français, ça dit quoi ?

[JMS]

Cela dit que leur objectif serait capable de séparer 400 paires de lignes à 2,8 et comme les films couleur courants font 80 paires de lignes, c'est facile de s'en sortir avec des Zeiss ! Mais n'ont pas dit ce que cela donnait dans les angles...

[vnr]

ah bon ok, s'ils le disent
De toute façon, finesse ou pas je m'en fiche,
le rendu est plus important a mes yeux,
or celui du film est inimitable.

100% d'accord! Les paires de lignes et autres nombres de pixels au milieu ou dans les angles n'ont pas apporté plus (voir même moins de certains points de vue) à la "pure beauté de la photo" pour reprendre le titre un peu kantien de ce fil 

[JMS]

"or celui du film est inimitable"...

mais si le rendu du film est imitable...reste à savoir ce que la voisine de Shoo en pense 

[vnr]

"or celui du film est inimitable"...

mais si le rendu du film est imitable...reste à savoir ce que la voisine de Shoo en pense 

Je dirais plutôt "souvent copié jamais égalé" 

[JMS]

moi je dirais "pas souvent copié parfois dépassé"

...quand on arrive à donner un rendu de Reala 100 à des prises de vues au Nikon D3 à 3200 ISO pour un mariage, on se dit que c'est pas si mal 

[gainsbourg × yebisu]

Je serais curieux de voir ce que ça donne de la Reala numerique a 3200 iso

(un D3 ça fait cher la reala quand meme...)

[JMS]

Que veux-tu, si la mesure donne 1/60 f/2,8 1600 ISO dans l'église, que l'officiant interdit le flash, que le marié adore le rendu de la Reala et qu'on fait le reportage pour lui faire plaisir, on se dit qu'à 100 ISO avec de la vraie Reala on serait à 1/15 f/1,4 mais que les zooms 24-70 et 70-200 n'ouvrent qu'à 2,8...on trouve des solutions de nos jours ! Pour la fête ensuite je suis même passé à 6400 ISO...j'aurais eu le D3s j'aurais osé 12800, soit 1/125 f/5,6 

[gainsbourg × yebisu]

bah on peut voir ? (quitte à flouter des visages si besoin...)

[JMS]

C'est dans mon dernier livre, chapitre "photo de mariage" 

...mais si j'ai le temps je mettrai un crop ou deux ce soir, cet AM je n'ai pas les photos sous la main !

[gainsbourg × yebisu]

Ah merci, j'essaierai de me le procurer (mais là je suis un peu loin...)


En fait ça m'intéresserait de pouvoir re-traiter les photos de mon mariage avec un rendu reala 
... ou mieux Portra NC !

(la reala c'est quand meme la plus proche d'un rendu numérique non ?)

[waldokitty]

moi je dirais "pas souvent copié parfois dépassé"

...quand on arrive à donner un rendu de Reala 100 à des prises de vues au Nikon D3 à 3200 ISO pour un mariage, on se dit que c'est pas si mal 

Il y en a en effet qui pour sentir l odeur des roses achètent un spray, je préfère aller aux champs (je me répète c est vrai  )

[JMS]

Tu te répètes trop, en effet ! Moi j'ai des roses dans mon jardin ! Beaucoup, en plus...

...mais si j'en veux en janvier, je sais me débrouiller aussi !

[JMS]

Résultat d'expériences contre nature...

(3200 ISO)

[JMS]

crop

[JMS]

...suite 3200 ISO

[JMS]

...crop

[JMS]

...5000 ISO

[JMS]

...crop.

Pour cette dernière image, elle a été shootée au 24 mm, 1/50 f/2,8 5000 ISO. Evidemment, elle aurait été possible avec de la vraie Reala, soit au 1/4 f/1,4 avec un M et Summilux, soit au 1/60 f/8 avec un flash cobra bourrin, comme 90% des photos de fête de mariage avant le numérique !

[JMS]

PS : pour Waldo j'ai aussi des M et de la Reala dans le congelateur, en 135 et en 120