GB Sports Photographer & The Panasonic LUMIX S1

Angles of View


5 Oct 2014 3:04PM
I am tempted by the Panasonic 8mm fisheye with its 180 degrees angle of view (presumably the diagonal). I am however confused as the 7-14mm wide angle lens is limited to 114 degrees at 7mm. I thought focal length and angle of view were related? Where am I wrong?

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Chris_L 5 5.2k United Kingdom
5 Oct 2014 5:04PM
They are related when comparing similar designs. It's the design of the lens in the fisheye that makes that difference, you could compare a 12mm fisheye to an 8mm fisheye.

Fisheye is a different class, those lenses have a lot of distortion.
6 Oct 2014 7:44AM
The relation between the angle of view and focal length is straightforward with linear spherical optics when field distortion is sort of negligible. Apparently it is not the case with the fisheye, especially as extreme as 180 degrees one. By classic formulas it must have 0mm focal distance which is entirely not possible in practice.
6 Oct 2014 7:09PM
Thanks for the responses folks, it is appreciated. I think the reasonable conclusion is that it is magic!Grin
Chris_L 5 5.2k United Kingdom
7 Oct 2014 12:12AM
Compare photographs taken with the two lenses you mention. Fisheye is great when used creatively but it may not be what you're expecting if you just want a wider view and it's not to everyone's taste.
Paul Morgan 18 19.4k 6 England
7 Oct 2014 1:03AM

Quote: I am however confused as the 7-14mm wide angle lens is limited to 114 degrees at 7mm. I thought focal length and angle of view were related? Where am I wrong?


I could be wrong here but I think the camera`s software including Lr etc make a number of auto corrections.

The 8mm is considered more of a specialist lens and auto corrections do not take place.
7 Oct 2014 12:41PM
Chris_L 5 5.2k United Kingdom
7 Oct 2014 2:54PM
Hmm interesting, the 7-14 does have a strongly curved front element, could well be that the cropping and straightening is done by software but it would have to be real-time though for the EVF to be accurate? Can see how cropping would be very easy to do real time.
mikehit 10 8.0k 13 United Kingdom
7 Oct 2014 3:08PM
What 'cropping ans straightening' are you referring to?
Chris_L 5 5.2k United Kingdom
7 Oct 2014 4:20PM
I'm referring to what Paul is suggesting, that the 8 isn't software corrected for distortion but that the 7 (-14) is
Paul Morgan 18 19.4k 6 England
7 Oct 2014 4:53PM
A simple way to tell is to process an image in one lot of software that does auto correct and another bit of software that does not and then compare the two side by side Smile
Paul Morgan 18 19.4k 6 England
7 Oct 2014 5:28PM
Here`s a quick comparison, the first processed in Lr, the second in capture one, I struggled a bit in capture one, I just find the interface chaotic and the two crops may be slightly different.

Taken with the 12-50 at the 12mm end, you can see the difference.

p7120018.jpg


Lr

p7120018-b.jpg


Capture One
ElSid 11 9 United Kingdom
9 Oct 2014 3:52PM

Quote:
Chris_L e2 Member
I'm referring to what Paul is suggesting, that the 8 isn't software corrected for distortion but that the 7 (-14) is



There wouldn't be any point in software correction for a fisheye as the distortion is intentional and built into the design.

Also the distortion correction options built into some software, and in some cases into camera firmware, are only intended to deal with residual disortion, they're not designed to handle full scale rectilinear corrections - with normal lenses like the 7-14 this is achieved by the optical design.


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