Paul M Clements

Red classes their 2K windowed sensor (2048 x 1152 pixels) as being Super 16mm. It occured to me however to examine whether standard 16mm lenses would be useable with the RedOne given the difference in aspect ratios between the two formats. In a nutshell normal 16mm lenses may have no problem covering the 2K area of the sensor. And some may argue they are a better fit.

The following diagram illustrates the physical area of 16mm (10.26 by 7.49mm) as well as the physical area of S16mm (12.51 x 7.41mm). There are two circles of coverage of both formats. Finally the portion of Red’s sensor that is used when shooting 2K windowed can be seen to fit inside the 16mm’s circle of coverage.

If you click on the name of each item in the key you can hide them in the diagram so as to get a clearer understanding of what you are looking at.

The diagonal from corner to corner of 16mm is 12.70mm. So the minimum diameter of a 16mm lenses circle of coverage ought to be 12.70 or greater in order for the image to be useable. By comparison the diagonal of the 2K area of the red sensor is 12.65mm; 0.05mm less than the minimum 16mm circle of coverage’s diameter.

Finally, even if a standard 16mm lens should have issues covering the 2K area of the sensor they will still be more than capable of covering full HD, since the area of the sensor used for 1080p (1920 Pixels by 1080 Pixels) is easily smaller than standard 16mm (Footage would require batch cropping in RedCine from the 2K source although future options for Windowed 1080p may become available).

The result of the above means that standard 16mm lenses, such as the Cooke 9-50mm T2.5 or Zeiss 10-100mm T2.0, do not need to undergo modifications for use with S16mm which lessens the width of the lens as well as lowers the T-Stop and can on some lenses lower the general quality of the image. It also means that there are further lens options for shooters to choose from, and due to the popularity of S16mm or 35mm, these standard lenses may very well offer a better price perfomance ratio.

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Disclaimer: In the interest of being mathematically correct and fair I should illustrate how the size of the 2K sensor area was arrived at and whether any part of this might have an effect on the results:

Each pixel of the Red Mysterium sensor occupies 29sq. micron. This means the vertical and horizontal length of each pixel is 0.0053851648071345040312507104915403mm. It is from this number that 2048 pixels gives us 11.028817525011464256001455085568mm which was rounded up to 11.03. It is also how I have measured the vertical length which contains 1152 pixels. The 29sq. micron pixel size taken directly from Red.com could however already been a rounded number from 0.0054mm length X 0.0054mm height. In which case each pixel would be 29.16sq Micron. The resulting difference in size for the 2K area would be 11.0592mm length (Compared to 11.03 posted above) and 6.2208 (Compared to 6.20 posted above). The diagonal would be 12.68874529967403829911747653133 or rounded to 12.69mm. Still 0.01mm less than the 12.7mm circle of coverage of 16mm. So by my calculations it would make no difference to the result (I hope they are correct!).

Some of the finest still lenses compare favourably to their Cine lens counterparts and for years companies such as Panavision, ARRI, Samcine, Century Optics and many others have been rehousing still lenses for use in cinema production. Furthermore films as recent as The Bourne Ultimatum have been shot using modified Nikkor lenses (View Article at International Cinematographers Guild). With care and attention to the choice of lens and it’s quality, still lenses can be used productively in a cine environment and get exceptional results.

Common problems do however exist. Firstly, the focus throw on still lenses is smaller than that of cine lenses. When attaching a follow focus to the lens it would require gearing in order to give the focus puller more movement in the focus knob compared to the movement of the focus on the lens. The focus barrel on still lenses more than often rotates in the wrong direction and focus marks are less accurate than on cine lenses.

Another common problem is controlling the aperture. Many still lenses control it via the body of the camera and subsequently have no physical control on the lens itself.

Cine and still lenses have different types of mounts. PL being one of the most commonly adopted cine mounts and Nikon F-Mount and Canon EF-Mount representing two of the most recognised still mounts. Usually these lenses need a complete overhaul and rehousing in order to correctly position the lens to the film plain or sensor of the camera. This is because the flange focal distance in still lenses is smaller than cine lenses and therefore a PL mount conversion cannot simply be added.

Generally speaking still lenses are usually not accurate enough for motion picture work even though they may be optically sound.

In order to combat the inherent problems special mounts for the RedOne, designed and manufactured by Birger Engineering Inc. Boston – Massachusetts, allow for the use of still lenses fitted with either Canon EF, Sigma SA, FourThirds (Olympus/Kodak/Leica & Others) or Nikon F mounts.

By coupling with the lenses automatic controls (Normally used by the corresponding DSLR camera bodies) the mounts can access the motors that control the lenses focus and aperture functions.

A focus puller can control the attached lens using a standard follow focus wheel (Prototype pictured above). By avoiding contact with the focus and aperture controls on the lens itself much of the perils of handling still lenses in a cine environment are removed.

The focus and aperture of a lens can also be controlled remotely, making it ideal for steadicam, handheld or crane work for example.

A further intended advantage of the mount is the lens data information can be converted from it’s native language to Cooke Optics’s /i or Broadcast, which will eventually be included in the camera. This would give the focus puller and post production live accurate data to work from.

Because there is no follow focus on a rig using such a mount, lenses can be swapped out quicker, allowing for greater efficiency on a shoot.

Breathing can be an issue in some still lenses (Although not all Cine lenses can lay claim to being free of it, especially older ones). But given the resolution in any frame shot on the RedOne a relatively simple animated mask can be applied in post to remove any breathing judged to be unsightly. There is also talk of a geared motor being used in conjunction with zoom lenses that will remove any breathing by adjusting the zoom slightly. The motor and the mount would be mapped to the specific lens so that as it is focussed the zoom would also be altered to counter the lenses natural breathing.

The mounts have yet to undergo real world testing so whether still lenses, used in conjunction with the Birger Mounts, are capable enough for use in demanding productions remains to be seen.

There have always been reasons for choosing cine over still lenses and for the large part reliability in the optics we know and trust will, and should, continue. Technology such as Birger’s mounts and the RedOne Digital Cinema Camera could however allow us to select from a wider range of lenses whilst lessening the traditional compromises and expense of rehousing them.

In April 2007 Cooke Optics, Leicester (UK), announced that Red would be adopting their /i Technology in the RedOne Digital Cinema Camera (See press release).

/i means lenses with “intelligence” and Cooke has been implementing their technology in their line of S4 lenses. /i compatible lenses will now send comprehensive, continuous lens data information to the RedOne camera.

The data includes vital information on lens setting, focusing distance, aperture and depth-of-field, hyperfocal distance, serial number, owner data, lens type and focal length in both metric and footage measurements. For zoom lenses, the zoom position is displayed.

Display of the data has previously required Cinematography Electronics’ /i Lens Display System and Cooke’s /i datalink. The information available from /i lenses on the RedOne will help focus pullers by supplying accurate live data via the camera as well as aid post production by including the information within the metadata of the shot footage.

As well as the inclusion within the camera body, Red’s own line of cine lenses include the /i technology. Many other companies have also taken on Cooke’s /i technology. They include Aaton, Avid, Arri, Cinematography Electronics, Dalsa, Preston Cinema Systems, CMotion, Pixel Farm, Service Vision and Mark Roberts Motion Control. The move towards standardization will hopefully help to streamline productions.