arithmetic

[crane-2]

hello,
I know you guys are good at maths.
I was trying to work out how much of what I see in the viewfinder will be in a
cubeface.
does that look right ? an 8mm fisheye on a 22.5 x 15 sensor

http://www.panagito.com/MISC/photo01.jpg

extra points for posting the calculation.

cheers

mick



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[Erik Krause]

crane wrote:

> I was trying to work out how much of what I see in the viewfinder will
> be in a cubeface.
> does that look right ? an 8mm fisheye on a 22.5 x 15 sensor
>
> http://www.panagito.com/MISC/photo01.jpg

Yes.

> extra points for posting the calculation.

Since standard fisheye in a first approximation maps an angle in reality
to a distance on the sensor you can simply use the sizes as you did in
your draft. If the fisheye shows 170° on 22.5mm it will show 90° on
11.9mm (22.5*90/170 or 15*90/113.34).

best regards
--
Erik Krause
http://www.erik-krause.de

[crane-2]

Quoting Erik Krause <[hidden email]>:

> crane wrote:
>
> > I was trying to work out how much of what I see in the viewfinder will
> > be in a cubeface.
> > does that look right ? an 8mm fisheye on a 22.5 x 15 sensor
> >
> > http://www.panagito.com/MISC/photo01.jpg
>
> Yes.
>
> > extra points for posting the calculation.
>
> Since standard fisheye in a first approximation maps an angle in reality
> to a distance on the sensor you can simply use the sizes as you did in
> your draft. If the fisheye shows 170° on 22.5mm it will show 90° on
> 11.9mm (22.5*90/170 or 15*90/113.34).

Erik get 20 points and an extra 10 for using the word reality (what's wrong with
reality(tm))

cheers

mick


> best regards
> --
> Erik Krause
> http://www.erik-krause.de


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[Keith Martin-2]

>an 8mm fisheye on a 22.5 x 15 sensor

What coverage percentage in the viewfinder? Many only give 95% or so.

k

[crane-2]

Quoting Keith Martin <[hidden email]>:

> >an 8mm fisheye on a 22.5 x 15 sensor
>
> What coverage percentage in the viewfinder? Many only give 95% or so.

2 points



> k


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[John Houghton]

--- In [hidden email], crane@... wrote:
> I was trying to work out how much of what I see in the viewfinder
> will be in a cubeface.
> does that look right ?  

Using PTGui rather than maths, the view should look more like:

http://www.johnhpanos.com/sig8cube.jpg

John

[crane-2]

Quoting panostar <[hidden email]>:

> --- In [hidden email], crane@... wrote:
> > I was trying to work out how much of what I see in the viewfinder
> > will be in a cubeface.
> > does that look right ?  
>
> Using PTGui rather than maths, the view should look more like:
>
> http://www.johnhpanos.com/sig8cube.jpg
15 points but no extra.
It does look very small when drawn accurately.

cheers

mick

> John


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