## Re: How to calculate the possible size of a panorma?

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• ... My apologies - this is not right. What I wrote here says that for a linear mapping the mapping is linear - this is circular reasoning. I was carried away
Message 1 of 6 , Sep 10, 2006
On Sunday, September 10, 2006 at 16:48, Erik Krause wrote:

> But the image circle radius for the linear mapping would be 12.6mm
> (considered 8mm focal length) instead of 11.3 like we take it as
> given. Hence we must adjust the focal length in the formula to fit
> those facts - it would result to 7.2mm.
>
> Now calculating again we find 40° for the 5mm radius and 50° for the
> 6.3mm radius - which is obviously 40° from the border. However, there
> is a difference in the middle radii of about 9%. (f.e. the 5.5mm
> radius is mapped from 43.8° with linear mapping and from 40.2° with
> sine mapping). I guess this was what Helmut Dersh meant when he wrote
> "you won't see a big difference between the two"...

My apologies - this is not right. What I wrote here says that for a
linear mapping the mapping is linear - this is circular reasoning.

I was carried away by the fancy diagrams I made to get it sorted out.
Yes, you get a higher resolution if you take the inner circle only.
However, you won't get only 80% of that resolution if you take the
full image circle (this would be the case if you use the outer parts
of the image *only*). You get about 90%...