Cinematography Mailing List - CML

Variable Primes


" Saw a few ads for the Arri/Zeiss Variable Primes. Although no technical discussion. Does any one out here have any info on these lenses. Are they just zooms, with a new name? Does focus hold throughout, do they track well or drift, Etc. Also any personal experience with the lenses, likes dislikes, comments."

I own a set of the three VP lenses. the VP1 is a 16mm to 30mm, the VP 2 is a 29mm to 60mm, and the VP 3 is a 55mm to 105mm. All are T2.2 *throughout* their zoom range. (Many zoom lenses cheat on this and vary as much as 3/4 stop throughout their zoom range) The name is some what misleading. They are indeed short range zooms, they do hold focus though out their zoom range.

The do cover the Full or "Silent" aperture (again, most zooms do not cover anything greater than the Academy aperture making their use somewhat scary on Super 35 productions, depending on extraction format)

They are extremely robust mechanically, they track extremely straight and repeat focal lengths with exacting tolerances (necessary if you are zooming with a motion control rig if you want multiple passes to match)

Sharpness and contrast? They are scary they are so good. They have less flare and better correction of chromatic aberration than most primes I have seen. I shot a couple of the scenes on Dante's Peak with the Zeiss VP lenses alongside the show's regular Panaflexes using Primo Prime lenses. During dailies, viewing a contact print from the original negative, you could not tell the difference between the Zeiss VP lenses and the Primo Primes. Many of the shots are in the movie.

Good correction of chromatic aberration is extremely important if you are doing blue or green screen mattes. If the different colors are imaging at different places on the film plane, the mattes are not going to fit!

Low flare and ghosting are important in the newer styles of photography where extremely bright highlights are in or near the edges of the frame.

From a design standpoint, you might wonder, "Why short zooms? Why not just build a really well designed and corrected set of primes?" The answer I got made sense: It *is* possible to utilize the lens design software and design a really high quality prime lens using aspheric lens elements, floating groups of elements for focus, and all the other tricks now available. After you have done that, you have a very expensive, well corrected, prime with lots of elements of glass. A complete set of focal lengths would be too expensive to produce or sell. Once you have spent all this design time and money for expensive aspheric glass and moving groups of elements, it wasn't too much more work to add a little more and have a short range zoom with *no* compromise in quality. Now that there needs to be only 3 lenses in the set, you can "go for broke" and make them the absolute best you can do.

By the way, contrary to popular myth, none the Panavision Primo Primes have *any* aspheric lens elements, they are all spherical.

Bill Bennett, Los Angeles

How accurate are the listed focal lengths?

I ask because I am frequently involved with matching camera footage and CGI backgrounds, in motion control tracking shots. With zoom lenses particularly, even when set to hard lens mark positions, there is often considerable inaccuracy as to actual, mathematical focal length as it pertains to angle of view. Once you position the lens between marks, it's time to guess and punt.

Don Canfield

>" Can you tell us what the close focus is (are), and whether or not they breathe very >much when you rack?"

The close focus is about 2.5 feet for the two wider lenses and 2.75 feet for the longer.

Only the VP1 (the 16mm to 30mm) exhibits some tendency to "breathe" and it's not bad, especially since it has great depth of field due to being so wide, so hopefully big focus pulls will be unnecessary... just rely on the depth to be there and go with the "splits".

They are very accurate. I just shot some tests with both Zeiss Primes and the Zeiss VP lenses. The match of angle of view was the same, unlike many zoom lenses, which are really "longer" than they are marked. (The Angenieux 25-250 HR is really more like a 29mm-290mm!)

If you wanted to be critically accurate, you could make an "angle of view" test chart for a given focal length and use that to set the focal length the VP lens before shooting a critical piece.

Bill Bennett, Los Angeles


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