How to calculate what Canon lens coverage

[Brent Daniels]

I need to figure out what Canon lens to rent that will cover a horizontal width of 20 feet from 6 feet away?

[Sheldon N]

Roughly an 11mm lens on full frame. Closest you'll get is a Sigma 12-24mm or Voigtlander 12mm for rectilinear lenses, or you could go fisheye to get a full 180 degree view.

http://www.tawbaware.com/maxlyons/calc.htm

[Bart_van_der_Wolf]

I need to figure out what Canon lens to rent that will cover a horizontal width of 20 feet from 6 feet away?

Hi Brent,

Depends on which Canon or other camera (actually the sensor size) the lens will be used on.

My DOF output quality planning tool allows to choose from a list of predefined cameras, and you can fill in the Focus distance at step 2.1 and the required coverage width at step 2.5.1 (with the  "adjust focal length" option selected). That would calculate a required focal length (for a 36mm wide sensor) of 10.74 mm and a horizontal FOV of 118 degrees.

The direct calculation of the field of coverage is not all that complicated, but there are usually additional considerations that need to be judged in addition to the angle of view. The choice of focal length will of course also influence e.g. Depth of Field, so you can continue with changing other parameters to better plan the shoot.

As Sheldon already suggested, you could consider using a fish-eye lens (the EF 8-15mm would allow to get very close to 11mm, and DPP allows to de-fish the non-linear distortion) if that is very important, but other fixed focal length lenses close to that might also be usable. Another consideration is to stitch multiple images, and crop to the desired coverage.

Cheers,
Bart

[Ellis Vener]

6(sq)+10(sq) = 136, and rounding the square root of that you roughly 60 degrees. Double that to get the full angle needed for the full 20 foot width of the subject , or about 120 degrees.

You left out the height of the subject

Now you need to find a lens that will cover 120 degrees along the long dimension of the camera's format andthat means 80 degrees coverage along the short side of the camera's format. Whichever  size format you are are working with, you'll need a lens that covers at least 145 degrees across the diagonal of the format. and that gets you into fisheye territory (like the Canon EF 8-15mm f/4L Fisheye zoom).

A rectilinear  alternative if the subject is static and you can use the EF 17mm f/4 TSE lens  and shift the lens laterally - or better still keep the lens in the same place and shift the camera body instead - There is a tutorial on that at http://www.reallyrightstuff.com/s.nl/it.I/id.38/.f - and stitch the frames together in a  program like PTGui or Photoshop CS 5/CS6/CC's Photomerge (File>Automate>Photomerge)

[Brent Daniels]

Thanks for the info.

We ended up shooting a Canon 5Dlll with a Canon 14mm set up on a Kessler slider as we were shooting up from the floor. In the end I am stitch combining 3 images in post to keep the distortion effects down. The slider worked a treat. It is all working out pretty nice in post.