Red Scarlet 4K video and various fisheye lenses

Written by Paul Bourke

August 2012

The following documents and evaluates a number of circular fisheye lenses on the Red Scarlet. The applications for such a combination are mostly for video recording for planetariums, other uses involve multiple cameras for 360 panoramic video capture. While the Scarlet is an APS-C sensor the whole sensor vertically is only available in 5K mode, this is unfortunately limited to 12fps. In 4K mode (30fps) the clipping is as shown for each tested lens. Note the Canon 5-15mm lens while easily the higher quality is designed for a fullframe sensor hence the large degree of clipping.

Lens and frame size Fisheye size Sample
Sigma 4.5mm
F2.6 - F22
12.5mm circle
Scarlet: 4K (30fps)
2320x2320
Sigma 4.5mm
F2.6 - F22
12.5mm circle
Scarlet: 5K (12fps)
2320x2320
Sunex 5.6mm
F5.6
14.5mm circle
Scarlet: 4K (30fps)
2700x2700
Canon 8-15mm
23mm circle
Scarlet: 4K (30fps)
Lens zoomed to maximum height
4260x4260
Canon 8-15mm
26.5mm circle
Scarlet: 5K (12fps)
Lens zoomed to maximum width
4930x4930
Coastal Optics 4.88mm
14.9mm circle
Scarlet: 4K (30fps)
2790x2790
Coastal Optics 4.88mm
14.9mm circle
Scarlet: 5K (12fps)
2790x2790

Example forming spherical (equirectangular) projection from a pair (180 degrees rotated) of fisheye images using the 4.5mm Sigma fisheye lens and the Red Scarlet in 4K mode, 30fps. Rendered at 4K and mask applied to hide the seam.

Example forming cylindrical projections from a pair (180 degrees rotated) of fisheye images using the 8-15mm Canon fisheye lens and the Red Scarlet in 4K mode, 30fps. Rendered at 8K and mask applied to hide the seam.

Vertical FOV: 40 degrees.

Vertical FOV: 60 degrees.

Vertical FOV: 80 degrees.

There are ways of dealing with the truncation, the fisheye can be rotated without introducing distortion. The consequence is loss of image at the opposite side of the fisheye to the direction of rotation.