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Author Topic: Can the zoom fish-eye give rectilinear images on FF camera?  (Read 1314 times)

RGF

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Can the zoom fish-eye give rectilinear images on FF camera?
« on: April 08, 2013, 10:17:35 AM »
Some one told me that the 8-15 fish-eye zoom can produce rectilinear images on a FF camera.  Is this true?????


At all focal lengths or only at 15 mm?   Or is a PS manipulation?

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Can the zoom fish-eye give rectilinear images on FF camera?
« on: April 08, 2013, 10:17:35 AM »

charlesa

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #1 on: April 08, 2013, 10:37:22 AM »
Only at 15 mm

neuroanatomist

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #2 on: April 08, 2013, 11:39:05 AM »
Only at 15 mm

Incorrect.

The 8-15mm is a fisheye lens at all focal lengths.  At 14-15mm on FF, it's a 'full frame fisheye' meaning the FoV fills the frame (you're getting an AoV of ~175°).  At 8mm on FF, it's a 'circular fisheye' meaning a circular 180° AoV inset in the rectangle (black borders).



If you want rectilinear from the 8-15mm fisheye, you must de-fish in post (at the cost of corner sharpness). 

The widest rectilinear Canon lens is the 14mm prime, Sigma has a rectilinear zoom that goes to 12mm.
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RGF

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #3 on: April 08, 2013, 11:49:38 AM »
Only at 15 mm

Incorrect.

The 8-15mm is a fisheye lens at all focal lengths.  At 14-15mm on FF, it's a 'full frame fisheye' meaning the FoV fills the frame (you're getting an AoV of ~175°).  At 8mm on FF, it's a 'circular fisheye' meaning a circular 180° AoV inset in the rectangle (black borders).



If you want rectilinear from the 8-15mm fisheye, you must de-fish in post (at the cost of corner sharpness). 

The widest rectilinear Canon lens is the 14mm prime, Sigma has a rectilinear zoom that goes to 12mm.

Neuro

Great info as usual.   Follow on question - what is the image quality of the sigma 12mm and how does it compare to the canon 14mm (which I have)

neuroanatomist

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #4 on: April 08, 2013, 11:59:24 AM »
No personal experience, but reviews suggest the Sigma's IQ isn't as good as the Canon prime.
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Random Orbits

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #5 on: April 08, 2013, 12:13:55 PM »
Some one told me that the 8-15 fish-eye zoom can produce rectilinear images on a FF camera.  Is this true?????


At all focal lengths or only at 15 mm?   Or is a PS manipulation?

LR has a lens profile for the Canon 15mm f/2.8 fisheye, which can be used to defish images well for the 8-15 f/4.  A defished 8-15 image at 15mm has a wider AOV than the EF 14 II rectilinear, so defishing does have at least one advantage.  The corners and edges of a defished image do soften up as one would expect, but it's decent if you don't pixel peep.

charlesa

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #6 on: April 08, 2013, 12:29:48 PM »
I stand corrected  ;)

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Re: Can the zoom fish-eye give rectilinear images on FF camera?
« Reply #6 on: April 08, 2013, 12:29:48 PM »