Neo Super Baltar

[Mistral75]

Les Super Baltar (20 mm, 25 mm, 35 mm, 50 mm, 75 mm et 100 mm, tous T/2,3) étaient des objectifs conçus par Bausch & Lomb au début des années 1960 et utilisés notamment pour tourner de grands classiques tels que Les oiseaux (1963), Le Parrain I (1972) et II (1974), Carrie (1976) ou encore La guerre des étoiles (1977). Ils sont parmi les premiers objectifs conçus pour le cinéma à avoir incorporé des terres rares (souvent radioactives) dans leurs lentilles.

Avec la mode du vintage, qui gagne aussi la recherche d'un certain rendu en tournage numérique, les Super Baltar ont de nouveaux été utilisés depuis 2013 pour tourner un certain nombre de films nettement moins inoubliables : Rush (Ron Howard, 2013), Last Days of Summer (Jason Reitman, 2013), Love Is Strange (Ira Sachs, 2014), etc.

Compte tenu de l'"appétit" pour les Super Baltar et de l'âge (ainsi que de l'état souvent moyen) de ces objectifs, des firmes artisanales ont entrepris de "recarrosser" leurs éléments optiques pour proposer des Super Baltar au fonctionnement moderne.

Pour autant, les Super Baltar, en état d'origine ou recarrossés, sont relativement rares de nos jours et chaque exemplaire a évolué à sa façon, rendant difficile la reconstitution d'un lot complet avec une signature homogène. Du coup, Brian Caldwell, connu sur Chassimages pour être le concepteur optique des Speed Boosters de Metabones et du Coastal Optics 60 mm f/4 UV-VIS-IR Apo Macro (apochromatique de l'infrarouge à l'ultraviolet en passant par le spectre visible) et pour collaborer avec Roger Cicala (Lens Rentals), est allé plus loin et a entrepris de recréer les Super Baltar à partir des plans d'origine, sous le nom de Neo Super Baltar.

Les Neo Super Baltar sont au nombre de neuf : 20 mm, 25 mm, 35 mm (deux versions), 50 mm, 75 mm et 100 mm, tous T/2,3, ainsi que 152 mm T/3 et 229 mm T/4,4. Ils couvrent tous le format Super35 ; le 75 mm et les focales plus longues couvrent le 24x36.

Caldwell Photographic livre des "cellules" (lentilles et diaphragme montés sur un châssis interne) aux spécialistes du recarrossage comme Van Diemen, P+S Technik, True Lens Services ou The Vintage Lens Company Ltd qui en font des objectifs complets, un peu comme les constructeurs automobiles au début du 20ème siècle livraient des ensembles châssis + groupe motopropulseur aux carrossiers.

Les Neo Super Baltar de The Vintage Lens Company Ltd sont vendus 10.200 GBP HT pièce.

Neo Super Baltar Brochure | Caldwell Photographic

NEO Super Baltars - Newsshooter

[Mistral75]

Un commentaire de Brian Caldwell sur les Neo Super baltar :

"My biggest advantage in this project is that I have the original optical prescriptions and blueprints used to make the original Baltars and Super Baltars.  These were rescued from certain death in a landfill by a quick-thinking B&L optical engineer named Bill Peck when the company got out of the photo and cine lens business.  At the time I was developing a large lens design database that Bill was interested in for his new company, so I had the great fortune of trading him a copy of my software for 6 big notebooks full of blueprints and a large box full index cards with handwritten optical prescriptions. 

For years I kept all of that unique vintage optical data on my shelf, not really knowing what to do with it.  But when Bill passed away a couple of years ago it dawned on me that I should try to re-manufacture some of the old lenses to their exact original formula.

So, to your question "how close will they be to the originals" I would answer "as close as humanly possible".  One hurdle of course is that B&L melted their own glass rather than buying it from established suppliers like Schott.  The reason for this is that the U.S. needed a domestic supplier during WWII.  In most cases, the difference between B&L glass and modern glass types is so small that it can be ignored.  In other cases there is a tiny difference that I had to adjust for.  For example, the front element of the original 20mm Super Balter used glass with and index of 1.804 and a dispersion (Abbe number) of 41.8.  The closest modern glass has an index of 1.7995 and a dispersion of 42.2, which is just barely outside the required manufacturing tolerances.  So, what I did was to carefully characterize the aberration balance of the original design, and then make tiny changes to a few select lens curvatures to regain the exact original performance.  Most of this was accomplished by changing the lens curvature of one or more cemented interfaces (i.e. "buried" surfaces).  It may be of some interest here that modern high index glasses tend to match the old B&L glasses very well.  This is due in part to the use of titanium instead of lead to achieve precisely matching index and dispersion values.  On the other hand some of the low index glasses turned out to be more challenging, but not so much that the original aberration balance couldn't be precisely matched.

Some of the earlier comments regarding the blackening of barrel parts and lens edges were pretty interesting.  The original blackening spec for the Super Baltars was simply "Lacquer Edges With PL-2", where presumably  PL-2 is a gloss black paint that is no longer available - at least I can't find it.  However, we do basically paint the lens edges with glossy black paint in the old fashioned way - by holding a small paintbrush against the ground edges while the lens is spinning on a spindle.  The coatings on the polished lens surfaces - which are more likely to contribute to the character of the lenses - is identical to the original spec:  "All lens coatings shall be middle purple.  500-600 mu."  In other words, the coatings are just single layer MgF2 adjusted to give a purplish reflection."

Source : Neo Baltar and Neo Super Baltar revival? CML Cinematography Mailing List