Lens settings

[Paul Hemans]

I have 6 Git2 cameras on a rig. I want to stitch the images together into an equirectangular view. The ultimate goal being a skybox.

I am using Hugin and I have set the Lens type to Full frame fisheye.

The specs say the GIT2 focal length is f/2.8 and a FOV of 170. However, lensfun has it at 5.57 

http://wilson.bronger.org/lensfun_coverage.html

Is the lensfun focal length the result of the 2.8 x the focal length multiplier?

https://www.lifewire.com/focal-length-multiplier-for-lenses-493735

Should I use 5.57 as the focal length in Hugin with a multiplier of 1?

Thanks.

[Greg 'groggy' Lehey]

On Monday, 6 February 2017 at 14:46:18 -0800, Paul Hemans wrote:
> I have 6 Git2 cameras on a rig. I want to stitch the images together
> into an equirectangular view. The ultimate goal being a skybox. I
> am using Hugin and I have set the Lens type to Full frame fisheye.
> The specs say the GIT2 focal length is f/2.8 and a FOV of 170.

f/2.8 is an aperture, not a focal length.

> However, lensfun has it at 5.57
> http://wilson.bronger.org/lensfun_coverage.html

No, that's a crop factor, not a focal length.

> Is the lensfun focal length the result of the 2.8 x the focal length
> multiplier?
> https://www.lifewire.com/focal-length-multiplier-for-lenses-493735

No, forget the f/2.8. It's not relevant here. Check your lens again
and see if you can find a real focal length, and the you can use 5.57
as crop factor.

If you can't find a focal length, and since it's a 170°, set the focal
length to 15 mm and crop factor 1. That should be close enough for
the control point detectors to align the images. If it's a 360°
horizontal panorama, they will then calculate a more accurate focal
length, which in my experience is not always what the manufacturer
complains (for example, I use an Olympus 8 mm lens, crop factor 2, but
the control point detectors are unanimous in saying that it's really
7.7 mm).

> Should I use 5.57 as the focal length in Hugin with a multiplier of 1?

No, definitely not.

Greg
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[Paul Hemans]

Groogle, thanks heaps. Helped a lot