Like all things digital, the technology in your beautiful new camera is heading towards obsolescence at an alarming rate. The same is true, though to a lesser extent, about that SLR lens with its own processors and motors for focus, aperture and stabilization. In the analog world of manual film lenses where a lifetime of use is guaranteed there has been a renaissance in the manufacture of high quality optics at all price points. Let's explore why.
New BeginningsAt the 2007 National Association of Broadcasters show (NAB) RED demonstrated three working RED One cameras and a short film shot on them by Peter Jackson. It marked the point at which the nay-sayers had to accept that RED's avowed mission to change the film industry forever was indeed underway. Now of course we are quite familiar with the formula for what constitutes the "film look" and what you need to produce it - 24 progressive frames per second, large sensors with wide dynamic range and therefore wide aperture lens mounts, plus logarithmic data capture to retain as much of that dynamic range as possible for post-processing.
Compact still cameras had for some time included the ability to record video via their small sensors. Canon decided to provide a similar but limited capability for their high-end Digital SLR's at the request of press agencies who wanted their reporters to be able to record short news clips on location. Completely unexpectedly, cash-strapped film makers pounced on the ability of these large sensor/large aperture tools to create 'the look' and soon pressured a surprised Canon into providing progressive 24 frame recording. Canon 5 and 7D's have now been used in numerous TV and commercial shoots but as serious film tools (at HD resolution anyway) they are being superseded by more traditional camcorder form factors now equipped with large sensors such as the pricey but gorgeous ARRI Alexa, Sony PMW F3, the cheaper Sony NEX FS-100 and Panasonic AF100. In fact the last two are derived from a popular new class of compact interchangeable-lens still/video cameras with large sensors but without optical viewfinders such as the Sony NEX series and Panasonic/Olympus Micro Four Thirds. For serious moving picture shooting, still camera lenses just won't cut it. The point about these new camera forms is that they can all take, or be easily adapted to take, the 35mm movie standard PL lens mount - hence the explosion in new movie lens choices.
What's the difference?Why aren't still camera lenses good enough for movies? Optically they are. If you were shooting a single static scene an SLR type lens is fine (turn the autofocus off). However film making is collaborative and stressful activity that involves lots of movement, even if it's a fan-flick filmed in your backyard, and there is a whole list of practical requirements that can explain the difference between the price of say, the manual Zeiss 35mm SLR lens at $1200 and the equivalent Zeiss 35mm Compact Prime movie lens at $3000.
- focus direction change
Movie lenses focus in the opposite direction. They just do.
- focusing rotation angle
The rotation of the focusing ring on a movies lens is two to three times that of a manual still camera lens. A still cameraman wants to snap as quickly as possible into focus whereas any change in focus in a movie must be smooth. Autofocus is not an option. Also movie lenses are often focused using a side gear wheel and the more teeth on the focusing ring the smoother the movement.
- distance marking accuracy
The larger focusing ring allows for a greater number of distance markers. These markers are calibrated to actual distances and movie focus pullers will often rely on them for accurate focus.
- no breathing with focus
Still lenses often 'breathe', That is the focal distance changes (zooms) slightly when the focus point changes. That's unacceptable on a cine lens.
- no length change throughout focusing
As you might have guessed by now the actual physical form of cine lenses is very important. They are often part of a whole built-up camera system with many accessories and additions including complex lens shades and filter holders. It's important that the physical size of the lens doesn't change during operation. Still lenses can change length hugely during focusing.
- same diameter throughout range
By the same token the lenses in a set of 'primes' (fixed focal length) will have the same diameter and the same position for the teethed focus and aperture rings. They will also as much as possible be the same length. This is so that lenses can be swapped out quickly without having to adjust the positions of all the accessories hanging off the camera rig.
- no aperture click stops
Still cameras usually control the lens aperture in discreet ½ or ⅓ stop increments. Any aperture change in a movie shot must be smooth and seamless, therefore no discreet stops. The iris on a cine lens often consists of more blades (18+) giving a more circular hole and softer out-of-focus highlights (bokeh).
- T-stops not F-stops
The f-stops on a still lens are a mathematical relationship between focal length and aperture size. On cine lenses T-stops are actual measured light transmission and are therefore guaranteed and more accurate.
- color-matched throughout range
Movie shots have to cut together with no jarring changes (unless deliberate). A range of cine prime lenses is therefore matched as much as possible in terms of color rendition and overall 'look'.
There are high-quality PL-mount cine lenses available now from half a dozen manufacturers at a range of prices (though you still might be shocked). We are dealing here only with prime lenses. There are zooms available from a number of brands such as Angenieux and Fuji but they tend to be large and expensive. RED do three three zooms at pretty reasonable cost but the best quality bang for buck is a prime lens. All prices are approximate and deals are available from all manufacturers for lens sets.
- Zeiss Compact Primes - $3,000 each
Re-engineered from still lenses and currently the cheapest available.
We don't know who actually makes them but very good quality. RED leader Jim Jannard knows a bit about optics after all (he created Oakley sunglasses).
A new entrant in the value stakes. Ex-East Geman factory.
A stop slower than most of the others but probably the price/quality leader. Gorgeous picture.
The industry standard. Great quality and a huge range of lenses.
The other industry standard with a different look. Originally a British design. Electronic lens data output.
The industry standard but a stop faster and with rationalized barrel sizes.
A recent entrant and arguably the daddy of them all. Super-light titanium barrels and impeccable optics. Hard to get hold of at the moment.
DecisionsIf you are using Canon or Nikon DSLR's for filming be aware that only the Zeiss Compacts and Schneiders can be fitted with suitable mounts. PL mounts won't work because of the mirrors in these cameras. In 2012 both Canon and Nikon will be bringing out compact interchangeable-lens still/video cameras with large sensors and it's highly unlikely that these cameras won't take PL lens adaptors.
No cine lenses are not cheap. But they are certainly cheaper than five years ago and their new-found relevance means that competition can only increase. Never forget that in ten years time when you have changed your main camera at least four times and there are 4K resolution TV broadcasts, your manual lenses will still be functional and producing high quality professional results.